pandas.DataFrame.astype

test.csv

col1,col2,col3
00,01,02
10,11,12
20,21,22
30,31,32

example1

import pandas as pd
df = pd.read_csv("test.csv")
print(df['col3'].astype(float))

#0     2.0
#1    12.0
#2    22.0
#3    32.0