Question

append vs. extend。我在这里得到了答案我只需要使用extend关键字而不是append。

def extractDollar(line): 
        global mainList
        temp=[]

        #lowercasing all the string
        line=line.lower()

        #storing all word starting with $ in a line in temp
        #then adding that  to existing list mainList
        #to form a single list and removing empty value
        temp= re.findall(r'$\w+',line)

        mainList=mainList+[j for i in zip(mainList,temp) for j in i]
        mainList= filter(None, mainList)

        return line

我有一个包含多个字符串的文件;每个字符串都有以$开头的单词，我想将以$开头的所有单词作为单个List（mainList）存储在文件中。
我写了这个函数来逐行读取文件。我正在获取临时数组，其中包含以$开头的所有值，但不能将re.findall返回的所有单个列表添加为单个主列表。

Answer 1

尝试reduce(sum, line)：

def extractDollar(line): 
        global mainList
        temp=[]

        #lowercasing all the string
        line=line.lower()

        #storing all word starting with $ in a line in temp
        #then adding that  to existing list mainList
        #to form a single list and removing empty value
        temp= re.findall(r'$\w+',line)

        mainList=mainList+[j for i in zip(mainList,temp) for j in i]
        mainList= filter(None, mainList)

        return reduce(sum,line)

结合`re.findall（）`返回的列表

1 个答案: