保持标题，同时附加到Pandas数据框w / Python

问题描述

所以我解析许多文件中包含的数据，循环遍历它们并将某些元素存储在列表中，并使用Python将每个生成的列表附加到Pandas的数据框中。

So I am parsing data contained in many files, looping through them and storing certain elements in a list, and appending each resulting list to a dataframe with Pandas using Python.

它的工作，除了我无法弄清楚如何保持头行添加。它不会消失或与每个附件重复。

It works, except I can't figure out how to keep the header row while appending. It either disappears or is duplicated with each append.

以下代码作为最新代码的示例：

The below code serves as an example of the latest code:

import pandas as pd

for i in range(1,4):
    data = [{'name': 'Company'+str(i), 'city': 'New York'}]

    stuff = []
    for element in data:
        stuff.append(element)

    df = pd.DataFrame(columns=["name",
                               "city"])

    for record in stuff:
        df = df.append(record, ignore_index=True)

    df.to_csv('test.csv', mode='a', header=False, index=False)

使用此代码，输出（csv文件）是：

With this code the output (csv file) is:

Company1    New York
Company2    New York
Company3    New York

但我正在寻找输出为：

name        city
Company1    New York
Company2    New York
Company3    New York

谢谢！

推荐答案

但是你设置了 header = False ：

df.to_csv('test.csv', mode='a', header=False, index=False)

你应该做：

df.to_csv('test.csv', mode='a', header=True, index=False)

您只需将其设置为 True 为第一次迭代，然后 False 为后续迭代

You just need to set it to True for the first iteration and then False for the subsequent iterations

基本上您只需执行以下操作：

Basically you just do something like the following:

# add this outside your for loop
writeHeader = True

# use the following where you write to csv
if writeHeader is True:
    df.to_csv('test.csv', mode='a', header=True, index=False)
    writeHeader = False
else:
    df.to_csv('test.csv', mode='a', header=False, index=False)

或类似

所以完整的东西看起来像：

So the complete thing looks like:

import pandas as pd
writeHeader = True

for i in range(1,4):
    data = [{'name': 'Company'+str(i), 'city': 'New York'}]

    stuff = []
    for element in data:
        stuff.append(element)

    df = pd.DataFrame(columns=["name",
                               "city"])

    for record in stuff:
        df = df.append(record, ignore_index=True)

    if writeHeader is True:
        df.to_csv('test.csv', mode='a', header=True, index=False)
        writeHeader = False
    else:
        df.to_csv('test.csv', mode='a', header=False, index=False)

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