Python read_csv 后在 Pandas 数据框中选择列时的关键错误
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/35831496/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Key error when selecting columns in pandas dataframe after read_csv
提问by Harry M
I'm trying to read in a CSV file into a pandas dataframe and select a column, but keep getting a key error.
我正在尝试将 CSV 文件读入 Pandas 数据帧并选择一列，但一直收到一个关键错误。
The file reads in successfully and I can view the dataframe in an iPython notebook, but when I want to select a column any other than the first one, it throws a key error.
该文件成功读入，我可以在 iPython 笔记本中查看数据帧，但是当我想选择除第一列之外的任何列时，它会引发关键错误。
I am using this code:
我正在使用此代码：
import pandas as pd
transactions = pd.read_csv('transactions.csv',low_memory=False, delimiter=',', header=0, encoding='ascii')
transactions['quarter']
This is the file I'm working on: https://www.dropbox.com/s/imd7hq2iq23hf8o/transactions.csv?dl=0
这是我正在处理的文件：https: //www.dropbox.com/s/imd7hq2iq23hf8o/transactions.csv?dl=0
Thank you!
谢谢！
回答by MaxU
use sep='\s*,\s*'so that you will take care of spaces in column-names:
使用sep='\s*,\s*'以便您处理列名中的空格：
transactions = pd.read_csv('transactions.csv', sep=r'\s*,\s*',
header=0, encoding='ascii', engine='python')
alternatively you can make sure that you don't have unquoted spaces in your CSV file and use your command (unchanged)
或者，您可以确保 CSV 文件中没有未加引号的空格并使用您的命令（未更改）
prove:
证明：
print(transactions.columns.tolist())
Output:
输出：
['product_id', 'customer_id', 'store_id', 'promotion_id', 'month_of_year', 'quarter', 'the_year', 'store_sales', 'store_cost', 'unit_sales', 'fact_count']
回答by Aswin Babu
if you need to select multiple columns from dataframe use 2 pairs of square brackets eg.
如果您需要从数据框中选择多列，请使用 2 对方括号，例如。
df[["product_id","customer_id","store_id"]]
回答by beta
The key error generally comes if the key doesn't match any of the dataframe column name 'exactly':
如果键与任何数据框列名称“完全”不匹配，通常会出现键错误：
You could also try:
你也可以试试：
import csv
import pandas as pd
import re
with open (filename, "r") as file:
df = pd.read_csv(file, delimiter = ",")
df.columns = ((df.columns.str).replace("^ ","")).str.replace(" $","")
print(df.columns)
回答by john collin
I finally got the answer to how to read a specific column:
我终于得到了如何阅读特定专栏的答案：
import pandas as pd
df=pd.read_csv('titanic.csv',sep='\t')
df['key']
Because pandas separator uses \t. I hope that works for you.
因为熊猫分隔符使用\t. 我希望这对你有用。
