python - 使用 csv 模块在 Python 中读取 csv 文件

Question

我正在尝试使用 csv 模块在 Python 中读取 csv 文件。为此，我使用读取器变量:

 with open('oneOrganization.csv', 'r', newline='') as csvfile2:
    reader2 = csv.DictReader(csvfile2, delimiter=',')

    for row in reader2:
        if row["role"] == []:
            row_dict['Role'] = "User"
        else:
            row_dict['Role'] = row["role"]

但是，运行该程序时，我意识到它确实进入了循环，尽管 cvs 文件存在并且确实名为 oneOrganization.csv。这可能是什么原因？

我是从Python开始的，通常这种方法是有效的。

Answer 1

阻止代码访问 if 循环 if row['Role']==[] 的问题是因为您试图以错误的方式查找空元素。
试试这个:

方法一:

with open('oneOrganization.csv','r') as file:
    reader = csv.DictReader(file,delimiter=',')
    my_list = list(reader)
    for row in reader:
        if row['test1'] in (None,''): # to check if cell is empty
            row_dict['Role'] = "User"
        else:
            row_dict['Role'] = row["role"]

方法2:由@Jean-François Fabre提供

with open('oneOrganization.csv','r') as file:
    reader = csv.DictReader(file,delimiter=',')
    for row in reader:
        if not row['test1']:
            row_dict['Role'] = "User"
        else:
            row_dict['Role'] = row["role"]

方法 3:“优雅的单衬” - 作者:@Jean-François Fabre

with open('oneOrganization.csv','r') as file:
    reader = csv.DictReader(file,delimiter=',')
    for row in reader:
        row_dict['Role'] = row["role"] or "User"

我在一个 csv 示例上尝试了它，可以如下表示:(np.array 形式)

[['test1' 'test2' 'test3']
 [   1       2       3   ]
 [   11      22      33  ]
 [           222     333]]

并使用此代码:

import csv

with open('test_csv.csv','r') as file:
    reader = csv.DictReader(file,delimiter=',')
    for row in reader:
        if row['test1'] in (None,''):
            print('no')
        else:
            print(row['test1'])

或者使用方法2:

import csv

with open('test_csv.csv','r') as file:
    reader = csv.DictReader(file,delimiter=',')
    for row in reader:
        if not row['test1']:
            print('no')
        else:
            print(row['test1'])

或者方法3

import csv

with open('test_csv.csv','r') as file:
    reader = csv.DictReader(file,delimiter=',')
    for row in reader:
        print(row['test1'] or 'no')

输出:

1
11
no

可以引用这个topic有关如何检查 csv 文件中的“单元格”是否为空的更多信息。