python - 如何将过滤后的字符串附加到 Python 中的新列表？

Question

我想将一个字符串附加到从旧列表中筛选出来的新列表。

到目前为止我尝试了什么:

languages = ['thai01', 'thai02', 'thai03', 'jap01', 'jap02', 'jap03']

thai = []
japanese = []


def filter_str(lang):
    if 'tha' in lang:
        return True
    else:
        return False


filter_lang = filter(filter_str, languages)
thai = thai.append(filter_lang)

print(thai)

我的预期输出是:

['thai01', 'thai02', 'thai03']

Answer 1

您可以使用列表理解:

languages = ['thai01', 'thai02', 'thai03', 'jap01', 'jap02', 'jap03']
thai = [x for x in languages if 'thai' in x]
print(thai)

输出:

['thai01', 'thai02', 'thai03']

为了帮助您理解这个单行代码的逻辑，请根据您的代码查看以下示例:

languages = ['thai01', 'thai02', 'thai03', 'jap01', 'jap02', 'jap03']

thai = []

def filter_str(lang):
    if 'tha' in lang:
        return True
    else:
        return False

for x in languages:
    if filter_str(x):
        thai.append(x)

print(thai)
# ['thai01', 'thai02', 'thai03']

检查字符串 'tha' 是否出现的 for 循环(在本例中借助您的函数)与上面的列表推导逻辑相同(尽管对于第一个示例，您甚至不需要该功能)。您还可以将列表推导式与您的函数结合使用:

languages = ['thai01', 'thai02', 'thai03', 'jap01', 'jap02', 'jap03']

def filter_str(lang):
    if 'tha' in lang:
        return True
    else:
        return False

thai = [x for x in languages if filter_str(x)]

print(thai)
# ['thai01', 'thai02', 'thai03']