Python 列表表达式 ，迭代器

Posted 2020-12-02 bug_x

python 环境 3.5

1、列表：
   s = [];
   for i in s:
      i = handleFunction(i);
      s.append(i)
2、列表
   s=[handleFunction(i) for i in s]

  或者
   s=[handleFunction(str(i)) for i in s]    //转为字符串
3、不用for循环（for循环的替代）map
   map(func, seq1[, seq2,…])   Python 3.0以上返回迭代器，2.7 返回list
   eg: seq 只有只有一个参数时： map==for
      **将元组转换成list*** >>> 
       list(map(int,(1,2,3))) [1, 2, 3] 
     ***将字符串转换成list*** >>>list(map(int,‘1234‘)) [1, 2, 3, 4] 
     ***提取字典的key，并将结果存放在一个list中*** >>> res=list(map(int,{"1":"a","2":"b"})) [1, 2] 
     #将小写转成大写 def u_to_l (s): return s.upper() print list(map(u_to_l,‘asdfd‘))

map(function, iterable, ...)

Return an iterator that applies function to every item of iterable, yielding the results. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel. With multiple iterables, the iterator stops when the shortest iterable is exhausted. For cases where the function inputs are already arranged into argument tuples,