Attempting to cut a Pandas dataframe to 3 decimal places

Question

I am trying to cut a column within a Pandas data frame column to 3 decimal places. I do not want to round the data, I just want to cut it so it will match other data. This is what I have tried; however, I get a TypeError: must be a real number, not list.

import pandas as pd


data = {'values': [5.52132, 6.572935, 7.21, 8.755, 9.9989]}
df = pd.DataFrame(data, columns = ['values'])

df['values'] = df['values'].astype(float).apply('%.3f'%['values'])

print(df))

Answer 1

You can use the following answer: https://stackoverflow.com/a/29257837/3944480

i.e.:

import pandas as pd
import math

to_places = 3 # yours number of places 3

def truncate(f, n):
    return math.floor(f * 10 ** n) / 10 ** n

data = {'values': [5.52132, 6.572935, 7.21, 8.755, 9.9989]}
df = pd.DataFrame(data, columns = ['values'])

print( df['values'].astype(float).apply(lambda number: truncate(number, to_places)) )

yielding:

0    5.521
1    6.572
2    7.210
3    8.755
4    9.998