Question

我有.csv个文件，试图依次获取每3行的平均值。表示第1至3行，然后是第4至6行，等等。这是一个小例子：

我期望得到的输出是：

5
14
23

我试图在python中做到这一点，并编写了以下代码。它不会返回我的期望：

infile = open("finename.csv", "r")
sum = 0
for i in range(len(infile)):
    if i+(i+1)+(i+2) %3 = 0,
        sum += infile[i]
        average = sum/3

您知道如何解决吗？

Answer 1

输入文件：

代码：

counter = 0
sum_value = 0
with open('a', 'r') as fh:
for line in fh:
    line = line.rstrip()
    sum_value += int(line)
    counter += 1
    if counter == 3:
        print ('%d' % (sum_value / counter))
        sum_value = 0
        counter= 0

输出：

5
14
23

Answer 2

您想要这样的东西吗？

import csv
import io

with open("file.csv") as csvFile:
    nbline = 0
    moy = 0
    listMoy = []
    reader = csv.reader(csvFile)

    for line in reader:
        moy = moy + int(line[0])
        nbline = nbline + 1
        if nbline == 3:
            moy = moy/3
            print moy
            listMoy.append(moy)
            moy = 0
            nbline = 0

with io.open("fileOut.csv", "w", encoding='UTF-8') as fichier:
    for moy in listMoy:
        fichier.write(u"{0}\n".format(moy))

Answer 3

您的if语句很奇怪，您正在检查3 * i + 3是否为3的倍数，这种情况总是如此。我会给您的步长arg以3乘3的方式。

infile = open('file.csv', 'r').readlines()
for i in range(2, len(infile), 3):
# starting at two to be sure to have always 3 values to check
    sum = int(infile[i-2]) + int(infile[i-1]) + int(infile[i])
    average = sum/3
    print(average)

Answer 4

with open(filename) as infile:
    lines = infile.readlines()
    for i in range(0, len(lines), 3):           #Split readline into subset of 3 elements
        val = map(int, lines[i:i+3])            #Convert elements in list to int
        print(sum(val)/3)                       #Get Avg

输出：

5
14
23

无需读取内存中的完整文件。谢谢@brunodesthuilliers。

res = []
temp = []
c = 0
with open(filename) as infile:
    for line in infile:
        if c == 3:
            res.append(sum(temp)/3)
            temp = []
            c = 0
        temp.append(int(line))
        c += 1
    if temp:
        res.append(sum(temp)/3)
print(res)

使用python在csv文件中进行统计操作

4 个答案: