将完整的整数列转换为字符串，并在pandas中使用逗号分隔千位

Question

Say I have population data stored in a column of a dataframe using pandas in python with Country names as row indices. How do I convert the whole column of numbers into string thousands separator using commas. Basically, I need 12345678,integer, converted into 12,345,678.

Answer 1

Using apply to format the numbers.

In [40]: ps.apply('{:,}'.format)
Out[40]:
CountryA    12,345,678
CountryB     3,242,342
dtype: object

In [41]: ps
Out[41]:
CountryA    12345678
CountryB     3242342
dtype: int64

Answer 2

You can use regex as well.

df['Population'].str.replace(r"(?!^)(?=(?:\d{3})+$)", ",")

See demo.

https://regex101.com/r/cVYAGw/1