编写Python脚本：从主目录300个子目录各随机提取一张图片至新文件夹

Got it, let's solve this problem exactly as you need it—we'll target each of your 300 top-level subdirectories individually, grab a random image from each (including all their nested subdirectories), and copy them to a new folder without conflicts.

Step-by-Step Explanation #

Here's the breakdown of what we'll do:

• Isolate your 300 top-level subdirectories: We'll only grab direct children of your master directory, not all nested folders.
• Recursively collect images per subdirectory: For each top-level folder, we'll search every nested subfolder for .jpeg, .png, or .jpg files.
• Randomly select one image: Pick a single random image from the collected list for each subdirectory.
• Copy to target folder safely: Handle duplicate filenames to avoid overwriting files, and ensure the target folder exists.

Full Working Script #

import os
import random
import shutil

# Configure your paths here
MASTER_DIRECTORY = "/path/to/your/master/directory"
TARGET_FOLDER = "/path/to/your/new/target/folder"

# Create target folder if it doesn't exist (no error if it does)
os.makedirs(TARGET_FOLDER, exist_ok=True)

# Get ONLY the top-level subdirectories (your 300 folders)
top_level_subdirs = [
    os.path.join(MASTER_DIRECTORY, subdir_name)
    for subdir_name in os.listdir(MASTER_DIRECTORY)
    if os.path.isdir(os.path.join(MASTER_DIRECTORY, subdir_name))
]

# Process each top-level subdirectory
for index, subdir_path in enumerate(top_level_subdirs, start=1):
    # Collect all valid images in this subdirectory (and its nested folders)
    image_paths = []
    for root, _, files in os.walk(subdir_path):
        for file in files:
            # Check for image extensions (case-insensitive to catch .JPEG/.PNG)
            if file.lower().endswith((".jpeg", ".png", ".jpg")):
                image_paths.append(os.path.join(root, file))
    
    # Skip if no images found in this subdirectory
    if not image_paths:
        print(f"⚠️ Warning: No images found in {subdir_path} — skipping this folder.")
        continue
    
    # Pick one random image from the list
    selected_image = random.choice(image_paths)
    
    # Handle duplicate filenames (use subdirectory name as prefix to avoid overwrites)
    subdir_name = os.path.basename(subdir_path)
    original_filename = os.path.basename(selected_image)
    target_filename = f"{subdir_name}_{original_filename}"
    target_path = os.path.join(TARGET_FOLDER, target_filename)
    
    # Copy the image to the target folder (preserves file metadata like timestamps)
    shutil.copy2(selected_image, target_path)
    print(f"✅ Copied: {selected_image} → {target_path}")

print("\n🎉 All done! Your 300 random images are in the target folder.")

Key Details to Note #

• Case-insensitive extension check: Using file.lower() ensures we catch images with uppercase extensions like .JPEG or .PNG that might otherwise be missed.
• Filename conflict prevention: By prepending the subdirectory name to the original filename, we avoid overwriting files that share the same name across different folders. If you prefer, you can replace this with a sequential number (e.g., 1_photo.jpg, 2_photo.jpg) by using f"{index}_{original_filename}" instead.
• Metadata preservation: shutil.copy2 is used instead of shutil.copy to keep important file metadata (like creation/modification times) intact.
• Error handling: We check if a subdirectory has no images and skip it with a warning, so your script won't crash unexpectedly.

内容的提问来源于stack exchange，提问作者heroZero