python求和函数怎么用 |
您所在的位置:网站首页 › python sum求和字典 › python求和函数怎么用 |
展开全部 sum(iterable[, start]) ,iterable为可迭代对象,如: sum([ ], start) #iterable为list列表 sum(( ), start ) #iterable为tuple元组 ...... 最后的值 = 可迭代对象里面的数相加的值 + start的值 start默认为0,如果62616964757a686964616fe4b893e5b19e31333361313861不写就是0,为0时可以不写 即sum()的参数最多为两个,其中第一个必须为iterable,例如: >>> sum([1, 2, 3,], 4) 10 >>> sum((1, 2), 3) 6 如果你写成sum([1,2,3]),start就是默认值 0 >>> sum([1, 2, 3]) 6 >>> sum([ ], 2) 2 >>> sum(( ), ) 0 >>> sum([1, 2] , 0) 3 当然iterable为dictionary字典时也是可以的: >>> sum({1: 'b', 7: 'a'}) 8 >>> sum({1:'b', 7:'a'}, 9) 17 下面这些写法目前是不被接受的(以list为例,其他iterable同理): 一、 >>> sum([1,2],[3,4]) Traceback (most recent call last): File "", line 1, in sum([1,2],[3,4]) TypeError: can only concatenate list (not "int") to list 二、 >>> sum(4,[1,2,3]) Traceback (most recent call last): File "", line 1, in sum(4,[1,2,3]) TypeError: 'int' object is not iterable 三、 >>> sum() Traceback (most recent call last): File "", line 1, in sum() TypeError: sum expected at least 1 arguments, got 0 四、 >>> sum(,2) SyntaxError: invalid syntax 五、 >>> sum(1,3) Traceback (most recent call last): File "", line 1, in sum(1,3) TypeError: 'int' object is not iterable 附其官方解释: >>> help(sum) Help on built-in function sum in module builtins: sum(...) sum(iterable[, start]) -> value Return the sum of an iterable of numbers (NOT strings) plus the value of parameter 'start' (which defaults to 0). When the iterable is empty, return start. |
今日新闻 |
推荐新闻 |
CopyRight 2018-2019 办公设备维修网 版权所有 豫ICP备15022753号-3 |