python - 在 Python 中计算目录中的一组扩展名(图像)

Question

我有包含混合文件的文件夹，并且只想要图像类型文件的数量。以下是返回目录中的总文件，而不仅仅是图像。我做错了什么？

extensions = ['.jpg','.png','.gif']
DL_path = os.getcwd()
for dirpath, dirnames, files in os.walk(DL_path):
    for original_file in files:
        todays_files = sum(1 for x in files if any(needle in original_file for needle in extensions))
        print(todays_files)

如果我有一个jpg，一个png，两个txt文件。 todays_files 应该返回 2，但它返回了 4。

Answer 1

您可以使用 set避免重复项:

>>> found_extensions = set()
>>> found_extensions.add('.png')
>>> found_extensions.add('.png')  # try to add .png again
>>> found_extensions
{'.png'}   # <-- appear only once

---

import os

extensions = {'.jpg','.png','.gif'}  # set literal

found_extensions = set()
for dirpath, dirnames, files in os.walk(os.getcwd()):
    for f in files:
        found_extensions.add(os.path.splitext(f)[-1])
        # ^-- duplicated item is not added

print(extensions & found_extensions)  # to get itersection (&) => filter
print(len(extensions & found_extensions))

---

更新获取每个目录的匹配文件数:

import os

extensions = {'.jpg','.png','.gif'}  # set literal

for dirpath, dirnames, files in os.walk(os.getcwd()):
    count = sum(os.path.splitext(f)[-1] in extensions for f in files)
    print(dirpath, count)

os.path.splitext(f)[-1] in extensions 将检查文件是否具有所需的扩展名，并返回 True (= 1)/假 (= 0)。将它们相加会给你想要的。

>>> True == 1
True
>>> False == 0
True
>>> sum([True, False, False, True, False])
2