使用SED保留变量空格并替换LS-Dyna输入文件坐标

Alright, let's solve this LS-Dyna input file coordinate replacement task. You've already dug through dozens of articles without luck, so let's focus on the exact format requirement here: 10-digit right-aligned columns for the 6 coordinates, updating test.txt to test2.txt while preserving the rest of the file structure.

Python Script Implementation #

This script will handle the formatting precisely and leave your file's comments and other content untouched except for the target coordinates:

# Set your new 6 coordinates here (order: XMN, XMX, YMN, YMX, ZMN, ZMX)
new_coordinates = [-150.0, 150.0, -75.5, 75.5, 10.0, 250.0]

# Read the original input file
with open("test.txt", "r") as input_file:
    all_lines = input_file.readlines()

updated_content = []
for line in all_lines:
    # Target only the BOX definition line
    if line.lstrip().startswith("*DEFINE_BOX_TITLE"):
        # Split the line to separate main data from LS-Dyna comments (marked with $)
        line_segments = line.split("$")
        main_data = line_segments[0].strip()
        
        # Break down the main data into fixed and variable parts
        data_parts = main_data.split()
        # The first 4 parts are static: *DEFINE_BOX_TITLE, Anonymous, BOX, Card
        fixed_prefix = data_parts[:4]
        
        # Format each coordinate to 10-digit right-aligned (adjust .4f for decimal precision)
        formatted_coords = [f"{coord:>10.4f}" for coord in new_coordinates]
        
        # Rebuild the main data section with new coordinates
        new_main_data = " ".join(fixed_prefix + formatted_coords)
        # Reattach the original comments to the line
        new_line = f"{new_main_data} ${'$'.join(line_segments[1:])}"
        updated_content.append(new_line)
    else:
        # Keep all non-target lines exactly as they are
        updated_content.append(line)

# Write the modified content to test2.txt
with open("test2.txt", "w") as output_file:
    output_file.writelines(updated_content)

Key Adjustments for Your Use Case #

• Integer Coordinates: If your coordinates are whole numbers instead of decimals, replace the format string from {coord:>10.4f} to {coord:>10d}.
• Decimal Precision: Tweak the .4f value to match your required precision (e.g., .2f for two decimal places).
• Multiple BOX Cards: If you have multiple *DEFINE_BOX_TITLE lines, add a check for the BOXID value to target specific boxes (e.g., filter lines containing BOXID 123).

Verify the Output #

After running the script, open test2.txt to confirm:

• The 6 coordinate columns are each 10 characters wide and right-aligned
• All comments (text after $) remain intact
• Other lines in the file are unchanged

内容的提问来源于stack exchange，提问作者LukasH