在python的列中添加數字

Question

我在像這樣的列中有一個數字列表

10,12,13

我想編寫一個Python程序，可以通過以下方式添加這些數字： 10+12=22, 10+13=23, 12+13=25任何人都可以提出任何建議。 謝謝

Answer 1

使用itertools combinations可以相當輕松地完成。 對於列表a ，您可以像這樣獲得n元素的所有和

from itertools import combinations

def sum_of_size(a, n):
    return map(sum, combinations(a, n))

編輯 ：如果您使用的是python 3，請改用它

from itertools import combinations

def sum_of_size(a, n):
    return list(map(sum, combinations(a, n)))

以你的例子

sum_of_size([10, 12, 13], 2)
# => [22, 23, 25]

Answer 2

這可能有效（使用Python 2.7）：

x = [10,12,13]
for i in range(len(x)):
    for j in range(i+1, len(x)):
        print x[i],' + ', x[j], ' = ', x[i]+x[j]

輸出：

10  +  12  =  22
10  +  13  =  23
12  +  13  =  25

已更新：假設文件有一行：10、12、13

import csv

f = open("test.dat", 'r')
try:
    reader = csv.reader(f)
    for row in reader:
        # convert array of string to int
        # http://stackoverflow.com/a/7368801/5916727
        # For Python 3 change the below line as explained in above link
        # i.e. results = list(map(int, results))
        results = map(int, row)
        for i in range(len(results)): 
            for j in range(i+1, len(results)): 
                print (results[i]+results[j])
finally:
    f.close()

Answer 3

如果由於某種原因不想使用itertools，可以通過這種方式實現。 通過給出的示例結果，我已經假定您要執行的操作：-

ColumnOfNumbers = [10,12,13]

def ListAddition(ColumnOfNumbers):

    #check if the list is longer than one item
    if len(ColumnOfNumbers)<=1:
        return "List is too short"

    #Define an output list to append results to as we iterate
    OutputList = []
    #By removing a number from the list as we interate we stop double results
    StartNumber = 0

    #Create a function to iterate - this is one less than the length of the list as we need pairs.
    for x in range(len(ColumnOfNumbers)-1):
        #Remove the first number from the list and store this number
        StartNumber = ColumnOfNumbers[0]
        ColumnOfNumbers.pop(0)

        #Iterate through the list adding the first number and appending the result to the OutputList
        for y in ColumnOfNumbers:
            OutputList.append(StartNumber + y)
    return OutputList

#Call the List Addition Function 
print (ListAddition(ColumnOfNumbers))

如果您想讓python從數字列文件中生成此列表，請嘗試以下操作：-

ColumnOfNumbers = []
file1 = open('test.dat','r')
for line in file1:
    ColumnOfNumbers.append(int(line))