无需正则表达式，优雅修改下划线分隔文件名指定字段的方法

Got it, let's fix this without messy repeated splits or regex. The key is to split the filename strategically only where we need to, then reconstruct it cleanly.

Approach 1: Split on the last underscore (most concise) #

Since your target field is the last segment before the file extension, we can split the filename once at the final underscore to separate the prefix from the target+suffix part. Then we just replace the target part and rejoin:

frameNumber = "&example"  # Your replacement string here
image_name = "centerOne_camera_2_2018-04-11_15:11:21_2.0.jpg"

# Split into prefix (everything before last underscore) and target+suffix
prefix, target_with_suffix = image_name.rsplit('_', 1)
# Extract the file extension (e.g., .jpg)
_, suffix = target_with_suffix.split('.', 1)
# Build the new filename
new_name = f"{prefix}_{frameNumber}.{suffix}"

This gives you exactly the format you want: centerOne_camera_2_2018-04-11_15:11:21_&example.jpg

Approach 2: Split all segments and replace the target index #

If you prefer working with all the underscore-separated parts explicitly, you can split once, replace the specific segment, then rejoin. This is great if you might need to modify other segments later:

frameNumber = "&example"
image_name = "centerOne_camera_2_2018-04-11_15:11:21_2.0.jpg"

parts = image_name.split('_')
# Extract the suffix from the last part
suffix = parts[-1].split('.')[1]
# Replace the target segment (the one containing 2.0) with your new string + suffix
parts[-1] = f"{frameNumber}.{suffix}"
# Rejoin all parts with underscores
new_name = '_'.join(parts)

Why this is better than your original approach #

• No repetitive split('_') calls (which are inefficient and hard to read)
• Uses proper string joining with underscores (so you don't end up with concatenated text like centerOnecamera2...)
• Dynamically extracts the file extension instead of hardcoding it (works for .png, .jpeg, etc., too)

内容的提问来源于stack exchange，提问作者deadcode