How to raise a column in pandas DataFrame to consecutive powers

user_10821432 0
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Is there a pythonic way to raise a column in DataFrame (xRaw) to consecutive powers? Is there something like 

xRaw[:,k] = xRaw.pow(k) for k in range(1,6)
pandas pow numpy python
3 Answers

This is a Vandermonde matrix, which numpy has a built-in function for np.vander

If you have

s = pd.Series([1,2,3,4,5])

Then

np.vander(s, 6)


array([[   1,    1,    1,    1,    1,    1],
       [   1,    2,    4,    8,   16,   32],
       [   1,    3,    9,   27,   81,  243],
       [   1,    4,   16,   64,  256, 1024],
       [   1,    5,   25,  125,  625, 3125]])

To add back to a df, you can use concat

df = pd.concat([df, pd.DataFrame(vander)], axis=1)
user_25356110

Numpy broadcast 

s.values**np.arange(6)[:,None]
Out[70]: 
array([[   1,    1,    1,    1,    1],
       [   2,    4,    8,   16,   32],
       [   3,    9,   27,   81,  243],
       [   4,   16,   64,  256, 1024],
       [   5,   25,  125,  625, 3125]], dtype=int64)

Assign it back 

s= pd.concat([s, pd.DataFrame(s.values**np.arange(6)[:,None],index=s.index)], axis=1)
user_79645270

I would do:

for i in range(6):
    xRaw["power: "+str(i)] = xRaw[column_to_be_raised] ** i

This is will generate a new column that takes its base from the column you want to raise for each exponent in the given range.

user_118970070
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