numpy - How to populate an empty array selectively? -

i new python , have tried accomplish following little success:

in folder there *.columns files contain 5 (0-4) columns , 500 rows. need sum columns 1-4 on *.columns files , plot result against first column of of (all equal).

i created empty array in want paste first (0) column of array "x_array3" , columns 1-4 "y_array0". of them have same size (500l, 5l).

could please give me advice how proceed? lost right now.

christian

import glob import numpy np   listoffiles = glob.glob("*.columns") y_array0 = 0  filename in listoffiles:     y_array1 = np.genfromtxt(filename, skip_header = 1, usecols = (0, 1, 2, 3, 4))     y_array0 = y_array0 + y_array1  x_array3 = np.genfromtxt(listoffiles[0], skip_header = 1, usecols = (0, 1, 2, 3, 4))  empty_array = np.empty(shape=(500, 5))  ausgabe_array = ??? here i'm stuck ???  np.savetxt('sx_dos.out', ausgabe_array) 

i have found working solution. read in columns single arrays , merge them @ end. still, can give me hint how 1 populates empty array selected items array (with size)?

chr.

import glob import numpy np  listoffiles = glob.glob("*.columns") y_array_s0 = 0 y_array_p0 = 0 y_array_d0 = 0 y_array_f0 = 0  filename in listoffiles:     y_array_s1 = np.genfromtxt(filename, skip_header = 1, usecols = (1))     y_array_s0 = y_array_s0 + y_array_s1      y_array_p1 = np.genfromtxt(filename, skip_header = 1, usecols = (2))     y_array_p0 = y_array_p0 + y_array_p1      y_array_d1 = np.genfromtxt(filename, skip_header = 1, usecols = (3))     y_array_d0 = y_array_d0 + y_array_d1      y_array_f1 = np.genfromtxt(filename, skip_header = 1, usecols = (4))     y_array_f0 = y_array_f0 + y_array_f1  x_array3 = np.genfromtxt(listoffiles[0], skip_header = 1, usecols = (0))  ausgabe_array = np.transpose(np.array((x_array3, y_array_s0, y_array_p0, y_array_d0,y_array_f0)))  np.savetxt('sx_dos.out', ausgabe_array)