python - Convert Select Columns in Pandas Dataframe to Numpy Array

Question

I would like to convert everything but the first column of a pandas dataframe into a numpy array. For some reason using the columns= parameter of DataFrame.to_matrix() is not working.

df:

  viz  a1_count  a1_mean     a1_std
0   n         3        2   0.816497
1   n         0      NaN        NaN 
2   n         2       51  50.000000

I tried X=df.as_matrix(columns=[df[1:]]) but this yields an array of all NaNs

Answer 1

the easy way is the "values" property df.iloc[:,1:].values

a=df.iloc[:,1:]
b=df.iloc[:,1:].values

print(type(df))
print(type(a))
print(type(b))

so, you can get type

<class 'pandas.core.frame.DataFrame'>
<class 'pandas.core.frame.DataFrame'>
<class 'numpy.ndarray'>