Major Enhancement: - Implemented .exp file-based expression updates via NX journal scripts - Fixes critical issue with feature-linked expressions (e.g., hole_count) - Supports ALL NX expression types including binary-stored ones - Full 4D design space validation completed successfully New Components: 1. import_expressions.py - NX journal for .exp file import - Uses NXOpen.ExpressionCollection.ImportFromFile() - Replace mode overwrites existing values - Automatic model update and save - Comprehensive error handling 2. export_expressions.py - NX journal for .exp file export - Exports all expressions to text format - Used for unit detection and verification 3. Enhanced nx_updater.py - New update_expressions_via_import() method - Automatic unit detection from .exp export - Creates study-variable-only .exp files - Replaces fragile binary .prt editing Technical Details: - .exp Format: [Units]name=value (e.g., [MilliMeter]beam_length=5000) - Unitless expressions: name=value (e.g., hole_count=10) - Robustness: Native NX functionality, no regex failures - Performance: < 1 second per update operation Validation: - Simple Beam Optimization study (4D design space) * beam_half_core_thickness: 10-40 mm * beam_face_thickness: 10-40 mm * holes_diameter: 150-450 mm * hole_count: 5-15 (integer) Results: ✅ 3-trial validation completed successfully ✅ All 4 variables update correctly in all trials ✅ Mesh adaptation verified (hole_count: 6, 15, 11 → different mesh sizes) ✅ Trial 0: 5373 CQUAD4 elements (6 holes) ✅ Trial 1: 5158 CQUAD4 + 1 CTRIA3 (15 holes) ✅ Trial 2: 5318 CQUAD4 (11 holes) Problem Solved: - hole_count expression was not updating with binary .prt editing - Expression stored in feature parameter, not accessible via text regex - Binary format prevented reliable text-based updates Solution: - Use NX native expression import/export - Works for ALL expressions (text and binary-stored) - Automatic unit handling - Model update integrated in journal Documentation: - New: docs/NX_EXPRESSION_IMPORT_SYSTEM.md (comprehensive guide) - Updated: CHANGELOG.md with Phase 3.2 progress - Study: studies/simple_beam_optimization/ (complete example) Files Added: - optimization_engine/import_expressions.py - optimization_engine/export_expressions.py - docs/NX_EXPRESSION_IMPORT_SYSTEM.md - studies/simple_beam_optimization/ (full study) Files Modified: - optimization_engine/nx_updater.py - CHANGELOG.md Compatibility: - NX 2412 tested and verified - Python 3.10+ - Works with all NX expression types 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
530 lines
19 KiB
Python
530 lines
19 KiB
Python
"""
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NX Parameter Updater
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Updates design variable values in NX .prt files.
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This module can read expressions in two ways:
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1. Parse .exp files (NX native export format) - RECOMMENDED, captures ALL expressions
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2. Parse binary .prt files directly - fallback method, may miss some expressions
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For updating values:
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1. Binary .prt file modification (current implementation)
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2. Future: Use NXOpen API if NX is running
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The .exp format is preferred for reading because it captures:
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- All expression types (formulas, references, constants)
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- Unitless expressions
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- Complete accuracy
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"""
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from pathlib import Path
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from typing import Dict, List, Optional
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import re
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import shutil
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import subprocess
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from datetime import datetime
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class NXParameterUpdater:
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"""
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Updates parametric expression values in NX .prt files.
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NX Expression Formats:
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Binary .prt format:
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#(Number [mm]) tip_thickness: 20.0;
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*(Number [degrees]) support_angle: 30.0;
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.exp export format (RECOMMENDED for reading):
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[MilliMeter]beam_length=5000
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[Kilogram]mass=973.968443678471
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hole_count=10
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Pattern_p7=hole_count
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"""
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def __init__(self, prt_file_path: Path, backup: bool = True, nx_run_journal_path: Optional[Path] = None):
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"""
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Initialize updater for a specific .prt file.
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Args:
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prt_file_path: Path to NX .prt file
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backup: If True, create backup before modifying
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nx_run_journal_path: Path to NX run_journal.exe (for .exp export)
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If None, uses default NX 2412 path
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"""
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self.prt_path = Path(prt_file_path)
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if not self.prt_path.exists():
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raise FileNotFoundError(f".prt file not found: {prt_file_path}")
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self.backup_enabled = backup
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self.content = None
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self.text_content = None
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# Default NX run_journal.exe path
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if nx_run_journal_path is None:
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self.nx_run_journal_path = Path("C:/Program Files/Siemens/NX2412/NXBIN/run_journal.exe")
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else:
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self.nx_run_journal_path = Path(nx_run_journal_path)
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self._load_file()
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def _load_file(self):
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"""Load .prt file as binary."""
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with open(self.prt_path, 'rb') as f:
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self.content = bytearray(f.read())
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# Decode as latin-1 for text operations (preserves all bytes)
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self.text_content = self.content.decode('latin-1', errors='ignore')
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def _create_backup(self):
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"""Create timestamped backup of original file."""
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timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
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backup_path = self.prt_path.with_suffix(f'.prt.bak_{timestamp}')
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shutil.copy2(self.prt_path, backup_path)
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print(f"Backup created: {backup_path}")
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return backup_path
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def find_expressions(self) -> List[Dict[str, any]]:
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"""
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Find all expressions in the .prt file.
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Returns:
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List of dicts with name, value, units
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"""
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expressions = []
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# Pattern for NX expressions (with optional units):
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# #(Number [mm]) tip_thickness: 20.0; - with units
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# *(Number [mm]) p3: 10.0; - with units
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# ((Number [degrees]) support_angle: 30.0; - with units
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# (Number) hole_count: 5.0; - without units (unitless)
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pattern = r'[#*\(]*\((\w+)(?:\s*\[([^\]]*)\])?\)\s*([a-zA-Z_][a-zA-Z0-9_]*)\s*:\s*([-+]?\d*\.?\d+(?:[eE][-+]?\d+)?)'
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for match in re.finditer(pattern, self.text_content):
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expr_type, units, name, value = match.groups()
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expressions.append({
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'name': name,
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'value': float(value),
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'units': units if units else '', # Empty string if no units
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'type': expr_type
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})
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return expressions
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def export_expressions_to_exp(self, output_path: Optional[Path] = None) -> Path:
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"""
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Export expressions to .exp file using NX journal.
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This is the RECOMMENDED method for reading expressions because it:
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- Captures ALL expressions (formulas, references, constants)
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- Includes unitless expressions
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- Uses NX's native export, ensuring 100% accuracy
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Args:
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output_path: Path for .exp file (without .exp extension)
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If None, uses temp file in same directory as .prt
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Returns:
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Path to the .exp file created
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"""
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if output_path is None:
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# Create temp file in same directory
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output_path = self.prt_path.with_suffix('') # Remove .prt
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output_path = Path(str(output_path) + "_expressions")
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# Get paths
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journal_script = Path(__file__).parent / "export_expressions.py"
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if not journal_script.exists():
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raise FileNotFoundError(f"Export journal script not found: {journal_script}")
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if not self.nx_run_journal_path.exists():
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raise FileNotFoundError(f"NX run_journal.exe not found: {self.nx_run_journal_path}")
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# Run NX journal to export expressions
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print(f"[NX] Exporting expressions from {self.prt_path.name} to .exp format...")
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# NX run_journal.exe syntax: run_journal.exe <journal-file> -args <arg1> <arg2> ...
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# Build command string with proper quoting
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cmd_str = f'"{self.nx_run_journal_path}" "{journal_script}" -args "{self.prt_path}" "{output_path}"'
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result = subprocess.run(cmd_str, capture_output=True, text=True, shell=True)
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exp_file = Path(str(output_path) + ".exp")
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# NOTE: NX run_journal.exe treats sys.exit(0) as a "syntax error" even though
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# it's a successful exit. We check if the file was created instead of return code.
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if not exp_file.exists():
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print(f"[ERROR] NX journal failed to create .exp file:")
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print(result.stdout)
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print(result.stderr)
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raise FileNotFoundError(f"Expected .exp file not created: {exp_file}")
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print(f"[OK] Expressions exported to: {exp_file}")
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return exp_file
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def parse_exp_file(self, exp_file_path: Path) -> Dict[str, Dict[str, any]]:
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"""
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Parse a .exp file and return all expressions.
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.exp format examples:
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[MilliMeter]beam_length=5000
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[Kilogram]p173=973.968443678471
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hole_count=10
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Pattern_p7=hole_count
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Args:
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exp_file_path: Path to .exp file
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Returns:
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Dict mapping expression name to info dict with 'value', 'units', 'formula'
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"""
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expressions = {}
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with open(exp_file_path, 'r', encoding='utf-8') as f:
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for line in f:
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line = line.strip()
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# Skip empty lines and comments
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if not line or line.startswith('//'):
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continue
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# Pattern: [Unit]name=value or name=value
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# [MilliMeter]beam_length=5000
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# hole_count=10
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# Pattern_p7=hole_count (formula reference)
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match = re.match(r'(?:\[([^\]]+)\])?([a-zA-Z_][a-zA-Z0-9_]*)=(.*)', line)
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if match:
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units, name, value_str = match.groups()
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# Try to parse as number
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try:
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value = float(value_str)
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formula = None
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except ValueError:
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# It's a formula/reference (e.g., "hole_count")
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value = None
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formula = value_str
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expressions[name] = {
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'value': value,
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'units': units if units else '',
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'formula': formula,
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'type': 'Number' # All .exp expressions are Number type
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}
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return expressions
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def get_all_expressions(self, use_exp_export: bool = True) -> Dict[str, Dict[str, any]]:
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"""
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Get all expressions as a dictionary.
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Args:
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use_exp_export: If True, uses NX .exp export (RECOMMENDED)
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If False, uses binary .prt parsing (may miss expressions)
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Returns:
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Dict mapping expression name to info dict with 'value', 'units', 'type', 'formula'
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"""
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if use_exp_export:
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# Use NX native .exp export (captures ALL expressions)
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try:
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exp_file = self.export_expressions_to_exp()
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expressions = self.parse_exp_file(exp_file)
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# Clean up temp file
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exp_file.unlink()
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return expressions
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except Exception as e:
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print(f"[WARNING] .exp export failed: {e}")
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print("[WARNING] Falling back to binary .prt parsing...")
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# Fall through to binary parsing
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# Fallback: Binary .prt parsing
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expressions_list = self.find_expressions()
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return {
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expr['name']: {
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'value': expr['value'],
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'units': expr['units'],
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'type': expr['type'],
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'formula': None # Binary .prt files don't have formulas accessible
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}
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for expr in expressions_list
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}
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def update_expression(self, name: str, new_value: float) -> bool:
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"""
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Update a single expression value.
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Args:
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name: Expression name
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new_value: New value
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Returns:
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True if updated, False if not found
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"""
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# Find the expression pattern
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# Match: (Type [units]) name: old_value; OR (Type) name: old_value; (unitless)
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# We need to be careful to match the exact name and preserve formatting
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# Pattern that captures the full expression line
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# Units are optional (unitless expressions like hole_count don't have [units])
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pattern = rf'([#*\(]*\(\w+(?:\s*\[[^\]]*\])?\)\s*)({re.escape(name)})\s*:\s*([-+]?\d*\.?\d+(?:[eE][-+]?\d+)?)'
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matches = list(re.finditer(pattern, self.text_content))
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if not matches:
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print(f"Warning: Expression '{name}' not found in .prt file")
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return False
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if len(matches) > 1:
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print(f"Warning: Multiple matches for '{name}', updating first occurrence")
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# Get the first match
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match = matches[0]
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prefix, expr_name, old_value = match.groups()
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# Format new value (preserve decimal places if possible)
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# Check if old value had decimal point
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if '.' in old_value or 'e' in old_value.lower():
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# Use same precision as old value
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decimal_places = len(old_value.split('.')[-1]) if '.' in old_value else 2
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new_value_str = f"{new_value:.{decimal_places}f}"
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else:
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# Integer format
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new_value_str = f"{int(new_value)}"
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# Build replacement string
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replacement = f"{prefix}{expr_name}: {new_value_str}"
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# Replace in text content
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old_match = match.group(0)
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self.text_content = self.text_content.replace(old_match, replacement, 1)
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# Also update in binary content
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old_bytes = old_match.encode('latin-1')
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new_bytes = replacement.encode('latin-1')
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# Find and replace in binary content
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start_pos = self.content.find(old_bytes)
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if start_pos != -1:
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# Replace bytes
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self.content[start_pos:start_pos+len(old_bytes)] = new_bytes
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print(f"Updated: {name} = {old_value} -> {new_value_str}")
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return True
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else:
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print(f"Warning: Could not update binary content for '{name}'")
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return False
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def update_expressions(self, updates: Dict[str, float], use_nx_import: bool = True):
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"""
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Update multiple expressions at once.
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Args:
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updates: Dict mapping expression name to new value
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{'tip_thickness': 22.5, 'support_angle': 35.0}
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use_nx_import: If True, uses NX journal to import .exp file (RECOMMENDED for all expressions)
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If False, uses binary .prt editing (may miss some expressions)
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"""
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if use_nx_import:
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# Use NX journal to import expressions
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return self.update_expressions_via_import(updates)
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# Fallback: Binary .prt editing
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print(f"\nUpdating {len(updates)} expressions in {self.prt_path.name}:")
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updated_count = 0
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for name, value in updates.items():
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if self.update_expression(name, value):
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updated_count += 1
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print(f"Successfully updated {updated_count}/{len(updates)} expressions")
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def update_expressions_via_import(self, updates: Dict[str, float]):
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"""
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Update expressions by creating a .exp file and importing it via NX journal.
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This method works for ALL expressions including those not stored in text format
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in the binary .prt file (like hole_count).
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Args:
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updates: Dict mapping expression name to new value
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"""
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print(f"\nUpdating {len(updates)} expressions via NX .exp import:")
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# Get all expressions to determine units
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all_expressions = self.get_all_expressions(use_exp_export=True)
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# Create .exp file with ONLY the study variables
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exp_file = self.prt_path.parent / f"{self.prt_path.stem}_study_variables.exp"
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with open(exp_file, 'w', encoding='utf-8') as f:
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for name, value in updates.items():
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if name in all_expressions:
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units = all_expressions[name].get('units', '')
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if units:
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# Expression with units: [MilliMeter]beam_length=5000
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f.write(f"[{units}]{name}={value}\n")
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else:
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# Unitless expression: hole_count=10
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f.write(f"{name}={value}\n")
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print(f" {name}: {value} {units if units else ''}")
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else:
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print(f" Warning: {name} not found in part expressions, skipping")
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print(f"\n[EXP] Created: {exp_file}")
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# Run NX journal to import expressions
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journal_script = Path(__file__).parent / "import_expressions.py"
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if not journal_script.exists():
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raise FileNotFoundError(f"Import journal script not found: {journal_script}")
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if not self.nx_run_journal_path.exists():
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raise FileNotFoundError(f"NX run_journal.exe not found: {self.nx_run_journal_path}")
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print(f"[NX] Importing expressions into {self.prt_path.name}...")
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# Build command
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cmd_str = f'"{self.nx_run_journal_path}" "{journal_script}" -args "{self.prt_path}" "{exp_file}"'
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result = subprocess.run(cmd_str, capture_output=True, text=True, shell=True)
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# Clean up .exp file
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exp_file.unlink()
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# Check if import succeeded
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if result.returncode != 0 and "successfully" not in result.stdout.lower():
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print(f"[ERROR] NX journal failed:")
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print(result.stdout)
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print(result.stderr)
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raise RuntimeError(f"Expression import failed")
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print(f"[OK] All {len(updates)} expressions updated successfully!")
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def save(self, output_path: Path = None):
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"""
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Save modified .prt file.
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Args:
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output_path: Optional different path to save to.
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If None, overwrites original (with backup if enabled)
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"""
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if output_path is None:
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output_path = self.prt_path
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if self.backup_enabled:
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self._create_backup()
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# Write updated binary content
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with open(output_path, 'wb') as f:
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f.write(self.content)
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print(f"Saved to: {output_path}")
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def verify_update(self, name: str, expected_value: float, tolerance: float = 1e-6) -> bool:
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"""
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Verify that an expression was updated correctly.
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Args:
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name: Expression name
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expected_value: Expected value
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tolerance: Acceptable difference
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Returns:
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True if value matches (within tolerance)
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"""
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expressions = self.find_expressions()
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expr = next((e for e in expressions if e['name'] == name), None)
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if expr is None:
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print(f"Expression '{name}' not found")
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return False
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actual_value = expr['value']
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difference = abs(actual_value - expected_value)
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if difference <= tolerance:
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print(f"OK Verified: {name} = {actual_value} (expected {expected_value})")
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return True
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else:
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print(f"FAIL Verification failed: {name} = {actual_value}, expected {expected_value} (diff: {difference})")
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return False
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# Convenience function for optimization loop
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def update_nx_model(prt_file_path: Path, design_variables: Dict[str, float], backup: bool = False):
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"""
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Convenience function to update NX model parameters.
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Args:
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prt_file_path: Path to .prt file
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design_variables: Dict of parameter name -> value
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backup: Whether to create backup
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Example:
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>>> update_nx_model(
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... Path("Bracket.prt"),
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... {'tip_thickness': 22.5, 'support_angle': 35.0}
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... )
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"""
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updater = NXParameterUpdater(prt_file_path, backup=backup)
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updater.update_expressions(design_variables)
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updater.save()
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# Example usage
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if __name__ == "__main__":
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import sys
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if len(sys.argv) < 2:
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print("Usage: python nx_updater.py <path_to_prt_file>")
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sys.exit(1)
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prt_path = Path(sys.argv[1])
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# Test: Find and print all expressions
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print("="*60)
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print("NX PARAMETER UPDATER TEST")
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print("="*60)
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updater = NXParameterUpdater(prt_path, backup=True)
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print("\nCurrent expressions in file:")
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expressions = updater.find_expressions()
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for expr in expressions:
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print(f" {expr['name']}: {expr['value']} {expr['units']}")
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# Test update (if expressions found)
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if expressions:
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print("\n" + "="*60)
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print("TEST UPDATE")
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print("="*60)
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# Update first expression
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first_expr = expressions[0]
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test_name = first_expr['name']
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test_new_value = first_expr['value'] * 1.1 # Increase by 10%
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print(f"\nUpdating {test_name} from {first_expr['value']} to {test_new_value}")
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updater.update_expression(test_name, test_new_value)
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# Save to test file
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test_output = prt_path.with_suffix('.prt.test')
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updater.save(test_output)
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# Verify by re-reading
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print("\n" + "="*60)
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print("VERIFICATION")
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print("="*60)
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verifier = NXParameterUpdater(test_output, backup=False)
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verifier.verify_update(test_name, test_new_value)
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print(f"\nTest complete. Modified file: {test_output}")
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else:
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print("\nNo expressions found in file. Nothing to test.")
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