Calculate numpy.std of each pandas.DataFrame's column?

Question

I want to get the numpy.std of each column of my pandas.DataFrame.

Here is my code:

import pandas as pd
import numpy as np
         


        

Answer 1

They're both right: they just differ on what the default delta degrees of freedom is. np.std uses 0, and DataFrame.std uses 1:

>>> prices.std(axis=0, ddof=0)
0    0.323259
1    0.173375
2    0.147740
dtype: float64
>>> prices.std(axis=0, ddof=1)
0    0.395909
1    0.212340
2    0.180943
dtype: float64
>>> np.std(prices.values, axis=0, ddof=0)
array([ 0.32325862,  0.17337503,  0.1477395 ])
>>> np.std(prices.values, axis=0, ddof=1)
array([ 0.39590933,  0.21234018,  0.1809432 ])