使用 DictWriter 更改列标题

Question

我正在编写一些代码以从输入 .txt 文件生成两个新的 CSV 文件。 .txt 文件有 40 列数据，我正在编写两个新的 csv 文件，每个文件只从 .txt 文件中获取 2 列。

我的代码运行良好，几乎完全符合我的需要。最后一步是重命名两个新 csv 输出中的原始标题。

这是我的代码：

import csv

QATargetHeaders = ['FNAME','LNAME']
FinalTargetHeaders = ['PROJECT_CODE','PHONE_NUMBER']

with open('TEST.txt','r') as csv_input, open('Test_QA2.csv','w') as csv_output:
    reader = csv.DictReader(csv_input, delimiter='^')
    writer = csv.DictWriter(csv_output, fieldnames=QATargetHeaders, extrasaction='ignore')
    writer.writeheader()
    for line in reader:
        writer.writerow(line)
with open('TEST.txt','r') as csv_input, open('Test_FINAL.csv','w') as csv_output:
    reader = csv.DictReader(csv_input, delimiter='^')
    writer = csv.DictWriter(csv_output, fieldnames=FinalTargetHeaders, extrasaction='ignore')
    writer.writeheader()
    for line in reader:
        writer.writerow(line)

对于 TEST_QA2.csv，我需要更改标题：

FNAME = First Name
LNAME = Last Name

对于 TEST_FINAL.csv，我需要更改标题：

PROJECT_CODE = PROJECT ID
PHONE_NUMBER = DEVICE1

有人可以帮我弄清楚如何在这里重写标题吗？ TargetHeaders 必须定义为 .txt 文件中的确切列名，以便我的作者知道要复制什么。提前谢谢您

Answer 1

line 是 dict。字典键用作标题。因此，您必须在编写新的 csv 之前重命名密钥。您可以通过 dict 理解来做到这一点。

import csv

QATargetHeaders = ['First Name','Last Name']
FinalTargetHeaders = ['PROJECT ID','DEVICE1']

map_QATargetHeaders = (('FNAME', 'First Name'), ('LNAME', 'Last Name'))
map_FinalTargetHeaders = (('PROJECT_CODE', 'PROJECT ID'), ('PHONE_NUMBER', 'DEVICE1LNAME'))

with open('TEST.txt','r') as csv_input, open('Test_QA2.csv','w') as csv_output:
    reader = csv.DictReader(csv_input, delimiter='^')

    writer = csv.DictWriter(csv_output, fieldnames=QATargetHeaders, extrasaction='ignore')
    writer.writeheader()
    for line in reader:
        line = {map[1]:line[map[0]] for map in map_QATargetHeaders}
        writer.writerow(line)

with open('TEST.txt','r') as csv_input, open('Test_FINAL.csv','w') as csv_output:
    reader = csv.DictReader(csv_input, delimiter='^')

    writer = csv.DictWriter(csv_output, fieldnames=FinalTargetHeaders, extrasaction='ignore')
    writer.writeheader()
    for line in reader:
        line = {map[1]:line[map[0]] for map in map_FinalTargetHeaders}
        writer.writerow(line)

Answer 2

不要使用writeheader，而是使用writerow 和字典，将旧标题映射到新标题。然后您可以像以前一样编写其他行。

QATargetHeaders = {'FNAME': 'First Name','LNAME': 'Last Name'}
FinalTargetHeaders = {'PROJECT_CODE': 'PROJECT ID','PHONE_NUMBER': 'DEVICE1'}
...
    writer = csv.DictWriter(csv_output, fieldnames=QATargetHeaders, extrasaction='ignore')
    writer.writerow(QATargetHeaders)  # instead of writeheader
    for line in reader:
        writer.writerow(line)
...

（从 Python 3.7 dictionaries preserve order 开始，列将以正确的顺序出现。如果使用早期版本的 Python，您将需要创建单独的字段名称列表，或使用 OrderedDict，以确保列以正确的顺序出现在 CSV 文件中。）