Convert data on reading csv in pandas

问题

I'm reading a .csv file into a pandas dataframe. The .csv file contains several columns. Column 'A' contains a string '20-989-98766'. Is it possible to only read the last 5 characters '98766' from the string when loading the file?

df = pd.read_csv("test_data2.csv", column={'A':read the last 5 characters})

output:

A
98766
95476
.....

回答1:

You can define a func and pass this as an arg to converters param for read_csv:

In [57]:
import io
import pandas as pd
def func(x):
    return x[-5:]
t="""column
'20-989-98766"""
df = pd.read_csv(io.StringIO(t), converters={'column': func})
df

​
Out[57]:
  column
0  98766

So here I define a func and pass this to converters in the form of a dict with your column name as the key, this will call the func on every row in your csv

so in your case the following should work:

df = pd.read_csv("test_data2.csv", converters={'A':func})

来源：https://stackoverflow.com/questions/43350601/convert-data-on-reading-csv-in-pandas