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Detailed explanation of the summation function sum() in python

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2021-04-27 09:14:286745browse

This article introduces you to the usage of python summation function sum(). It has certain reference value. Friends in need can refer to it. I hope it will be helpful to everyone.

Detailed explanation of the summation function sum() in python

I originally wanted to calculate the sum of several Int values. I thought it was a simple thing, but the result turned out to be very sad, for example

>>>sum = sum(1,2,3)         #结果很明显出现问题报错
TypeError: sum expected at most 2 arguments, got 3

Silly I thought I could only calculate the sum of the first two numbers to be equal to 3, so I tried again

>>>sum = sum(1,2)           #结果还是报错
TypeError: 'int' object is not iterable

In fact, what we know about the syntax of the sum() function is this

sum(iterable[, start])

where

  • iterable – Iterable objects, such as: list, tuple, set, dictionary.

  • start – Specifies the parameters for addition. If this value is not set, it defaults to 0.

That is to say, the final value obtained by sum() = the sum of the numbers in the iterable object (dictionary: key value addition) start value (if start is not written value, the default is 0) Therefore, the sum of the several int values ​​I want can be written like this

>>>sum = sum([1,2,3])             # in list
6

If we add start, it should be like this

>>> sum = sum([1,2,3],5)          #in list +start
11
>>> sum = sum((1,2,3))            #in tuple
6
>>> sum = sum({1,2,3})            #in set
6
>>> sum = sum({1:5,2:6,3:7})      #in dictionary key
6
>>> sum = sum(range(1,4))         #in range()
6

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