如何根据长度选择csv文件中的行？答案

【问题标题】：How to select rows in a csv file beased on the lenght?如何根据长度选择csv文件中的行？
【发布时间】：2021-05-11 07:02:59
【问题描述】：

我正在尝试根据行的长度来选择行。我的 csv 文件中的某些行有 5 个项目，有些有 20 个项目，有些有 40 个。如果它们的长度在 24 到 34 之间，我想收集所有行。所以我尝试了以下代码：

my_path = r'c:\data\FF\Desktop\my_files' 

for file in os.listdir(my_path):
    path_file = os.path.join(my_path, file)
    with open(path_file, 'r') as output:
        reader = csv.reader(output, delimiter = ',')
        read = [row for row in reader if row] 
        for row in read:
            if len(row) > 24 or len(row) < 34:
                if row[9] == '3080':
                    print(row[0] + ',' + row[24] + ',' + row[25] + ',' 
                          + row[26] + ',' + row[27] + ',' + row[28] + ',' + row[29]
                          + ',' + row[30] + ',' + row[31] + ',' + row[32] + ',' + row[33] + ','
                          + row[34])

我收到以下错误：

  File "C:\data\FF\Desktop\Python\PythongMySQL\untitled2.py", line 15, in <module>
    if row[9] == '3080':

IndexError: list index out of range

我希望得到几行长度在 24 到 34 之间的行。

【问题讨论】：

检查长度时使用and 而不是or。所有行都符合or
@MarkTolonen 我将or 更改为and 收到以下错误：` + row[34]) IndexError: list index out of range`
这需要 35 行。
@MarkTolonen 还是同样的错误...
或将其设为 pythonic if 24 < len(row) < 34 :，然后一旦确定该行的长度

标签： python list csv for-loop if-statement

【解决方案1】：

正如您所说，您希望长度介于 24 和 34 之间，因此您必须按如下方式更新该条件：

my_path = r'c:\data\FF\Desktop\my_files' 

for file in os.listdir(my_path):
    path_file = os.path.join(my_path, file)
    with open(path_file, 'r') as output:
        reader = csv.reader(output, delimiter = ',')
        read = [row for row in reader if row] 
        for row in read:
            if len(row) >= 24 and len(row) <= 34:
                if row[9] == '3080':
                    print(row[0] + ',' + row[24] + ',' + row[25] + ',' 
                          + row[26] + ',' + row[27] + ',' + row[28] + ',' + row[29]
                          + ',' + row[30] + ',' + row[31] + ',' + row[32] + ',' + row[33] + ','
                          + row[34])

注意运算符更新。这个小改动将确保您在24 - 34 中拥有您所期望的行。

【讨论】：

@E.Mancebo 是的，仍然收到同样的错误。

【解决方案2】：

这是一个示例，其中数据行的长度从 20 到 39 不等。只有长度在 24 到 34 之间且列 9 == 3080 的行才会打印：

input.csv

0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20
0,1,2,3,4,5,6,7,8,3080,10,11,12,13,14,15,16,17,18,19,20,21
0,1,2,3,4,5,6,7,8,3080,10,11,12,13,14,15,16,17,18,19,20,21,22
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30
0,1,2,3,4,5,6,7,8,3080,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31
0,1,2,3,4,5,6,7,8,3080,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32
0,1,2,3,4,5,6,7,8,3080,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33
0,1,2,3,4,5,6,7,8,3080,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36
0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37
0,1,2,3,4,5,6,7,8,3080,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38

test.py

import csv

with open('input.csv','r',newline='') as f:
    r = csv.reader(f)
    for row in r:
        if 24 <= len(row) <= 34:
            if row[9] == '3080':
                print(','.join([row[0]] + row[24:]))

输出：

0,24,25,26,27,28,29,30,31
0,24,25,26,27,28,29,30,31,32
0,24,25,26,27,28,29,30,31,32,33

【讨论】：

为什么34和38行没有被打印出来？
0-34 是长度 35，0-38 是长度 39，在 24-34 长度之外。如果这让您感到困惑，我觉得您没有很好地解释您的要求
是的。明白了。谢谢你。你能支持我的问题吗？