import numpy as np

from ROOT import TFile
import root_numpy as rnp

import numpy.lib.recfunctions as rfn

r1=np.random.normal(0, 1, (1000,1))
r2=np.random.uniform(-1, 1, (1000,1))

array=rfn.merge_arrays((r1,r2))
array.dtype.names=["gauss", "uniform"]

ofile=TFile.Open("tree.root", "recreate")
otree=rnp.array2tree(array)

ofile.cd()
otree.Write()

ofile.Close()