如何在Python中将过滤后的字符串附加到新列表中？

Question

我想在从旧列表筛选出来的新列表中附加一个字符串。你知道吗

到目前为止我试过的：

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)

我的预期产出是：

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

Answer 1

执行下一步而不是使用thai.append：

thai.extend(filter(filter_str, languages))

Answer 2

您可以使用列表：

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

输出：

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

为了帮助您理解此oneliner的逻辑，请参见以下基于代码的示例：

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for是否出现的'tha'循环（在本例中是在函数的帮助下）与上面的列表理解逻辑相同（尽管在第一个示例中，您甚至不需要函数）。您还可以结合使用列表理解功能：

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']

Answer 3

也可以将filter与lambda函数一起使用

languages = ['thai01', 'thai02', 'thai03', 'jap01', 'jap02', 'jap03']
thai = list(filter(filter_str,languages))  # or  thai = list(filter(lambda x:'thai' in x,languages))

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

或列表理解

thai = [y for y in languages if 'tha' in y]