Python头文件添加到csv文件 [英] Pythonically add header to a csv file

问题描述

我写了一个Python脚本合并两个csv文件，现在我想添加一个头到最后的csv。我尝试按照此处我得到以下错误：预期字符串，float found 。

I wrote a Python script merging two csv files, and now I want to add a header to the final csv. I tried following the suggestions reported here and I got the following error: expected string, float found. What is the most pythonic way to fix this?

这里是我使用的代码：

import csv

with open('combined_file.csv', 'wb') as outcsv:
    writer = csv.DictWriter(outcsv, fieldnames = ["Date", "temperature 1", "Temperature 2"])
    writer.writeheader()

    with open('t1.csv', 'rb') as incsv:
        reader = csv.reader(incsv)
        writer.writerows(row + [0.0] for row in reader)

    with open('t2.csv', 'rb') as incsv:
        reader = csv.reader(incsv)
        writer.writerows(row[:1] + [0.0] + row[1:] for row in reader)

推荐答案

DictWriter（） > dictionaries 。如果你想要做的是写一个初始标题，使用一个常规的 csv.writer（）并传入一个简单的行为：

The DictWriter() class expects dictionaries for each row. If all you wanted to do was write an initial header, use a regular csv.writer() and pass in a simple row for the header:

import csv

with open('combined_file.csv', 'wb') as outcsv:
    writer = csv.writer(outcsv)
    writer.writerow(["Date", "temperature 1", "Temperature 2"])

    with open('t1.csv', 'rb') as incsv:
        reader = csv.reader(incsv)
        writer.writerows(row + [0.0] for row in reader)

    with open('t2.csv', 'rb') as incsv:
        reader = csv.reader(incsv)
        writer.writerows(row[:1] + [0.0] + row[1:] for row in reader)

替代方法是在复制数据时生成字典：

The alternative would be to generate dictionaries when copying across your data:

import csv

with open('combined_file.csv', 'wb') as outcsv:
    writer = csv.DictWriter(outcsv, fieldnames = ["Date", "temperature 1", "Temperature 2"])
    writer.writeheader()

    with open('t1.csv', 'rb') as incsv:
        reader = csv.reader(incsv)
        writer.writerows({'Date': row[0], 'temperature 1': row[1], 'temperature 2': 0.0} for row in reader)

    with open('t2.csv', 'rb') as incsv:
        reader = csv.reader(incsv)
        writer.writerows({'Date': row[0], 'temperature 1': 0.0, 'temperature 2': row[1]} for row in reader)

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