以csv对每列求和

Question

给定一个csv文件

A,0,0,1,0
B,0,0,1,0
C,0,0,1,0
D,0,0,1,0
E,0,0,1,0
F,0,0,0,1

我想计算每列的总数。有没有一种比以下方法更具吸引力或更有效的方法来做到这一点：

import csv

totals = [0]*4

for row in csv.reader(csvfile):
    counts = [ int(x) for x in row[-4:] ]
    totals = [ sum(x) for x in zip(counts, totals) ]
print(totals)

Answer 1

您可以使用numpy的^{}读取文件，然后对索引列和数组进行切片^{}：

import numpy as np

my_data = np.genfromtxt(csvfile, delimiter=',')
print(my_data[:,1:].sum(axis=0))

给出：

[0. 0. 5. 1.]

Answer 2

以下是一种无需外部LIB即可完成工作的综合方法：

matrix = [[int(i) for i in row[-4:]] for row in csv.reader(csvfile)]

totals = [sum(array[i] for array in matrix) for i in range(4)]

Answer 3

事先转置csv文件，跳过现在的标题列，只计算每行的总和

cr = zip(*csv.reader(csvfile))
next(cr)

result = [sum(map(int,x)) for x in cr]
print(result)

[0, 0, 5, 1]

不过，在扩展zip的参数时要小心，因为它会将整个文件加载到内存中