Pandas 在 csv 读取后删除第一列
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Pandas drop first columns after csv read
提问by Ti me
Is there a way to reference an object within the line of the instantiation ?
有没有办法在实例化行中引用对象？
See the following example : I wanted to drop the first column (by index) of a csv file just after reading it (usually pd.to_csv outputs the index as first col) :
请参见以下示例：我想在读取后删除 csv 文件的第一列（按索引）（通常 pd.to_csv 将索引输出为第一列）：
df = pd.read_csv(csvfile).drop(self.columns[[0]], axis=1)
I understand self should be placed in the object context but it here describes what I intent to do.
我理解 self 应该放在对象上下文中，但它在这里描述了我打算做什么。
(Of course, doing this operation in two separate lines works perfectly.)
（当然，在两个单独的行中执行此操作非常有效。）
采纳答案by jpp
One way is to use pd.DataFrame.iloc:
一种方法是使用pd.DataFrame.iloc：
import pandas as pd
from io import StringIO
mystr = StringIO("""col1,col2,col3
a,b,c
d,e,f
g,h,i
""")
df = pd.read_csv(mystr).iloc[:, 1:]
# col2 col3
# 0 b c
# 1 e f
# 2 h i
回答by Aritesh
Assuming you know the total number of columns in the dataset, and the indexes you want to remove -
假设您知道数据集中的总列数，以及要删除的索引 -
a = range(3)
a.remove(1)
df = pd.read_csv('test.csv', usecols = a)
Here 3 is the total number of columns, and I wanted to remove 2nd column. You can directly write index of columns to use
这里 3 是总列数，我想删除第二列。您可以直接编写要使用的列索引
