Write multiple numpy arrays along with strings in csv

Question

Seems like a simply thing to do, but yet I fail. I want to write the following arrays into one line in a csv file, alongside with other strings (ie "\\n" ). The values should be separated by semicolons.

I create the arrays from lists

auth_list = ['5,2.6,5.23515389636e-11,0.00444005161574,0.0644299145707,0.04,0.0037037037037', '1,5.0,5.65187364062e-12,0.0,0.0605326876513,0.0,0.000740740740741']
aff_list = [(1, 0.003105590062111801), (1, 0.001838235294117647)]
comm_list = ['', '4,17.5,0.00584085856718,0.0002890919969,0.278790504782,0.0140752484561,0.0029973357016,0.00044404973357', '0,0.0,0.000218693005322,3.33471210416e-07,0.232075228649,0.0,0.000222024866785,0.0', '0,0.0,0.00025235732634,6.73003774237e-07,0.233652374653,0.0428571428571,0.000555062166963,0.0']

I proceed turning them into arrays

import numpy
auth_array = numpy.genfromtxt(auth_list, delimiter=",")
aff_array = numpy.array(aff_list) # Here I don't have to use numpy.genfromtext, don't know why
auth_array = numpy.genfromtxt(aff_list, delimiter=",")

These arrays already have no commas. I calculate the means using

auth_mean = numpy.mean(auth_array, axis=0)
aff_mean = numpy.mean(aff_array, axis=0)
comm_mean = numpy.mean(comm_array, axis=0)
title = "Happy New Year"

Using print , I see in the terminal

auth_mean = [  3.00000000e+00   3.80000000e+00   2.90017063e-11   2.22002581e-03
          6.24813011e-02   2.00000000e-02   2.22222222e-03]
aff_mean = [ 1.          0.00247191]
comm_mean = [  1.33333333e+00   5.83333333e+00   2.10396963e-03   9.66994906e-05
          2.48172703e-01   1.89774638e-02   1.25814091e-03   1.48016578e-04]

The arrays always have the same dimension.

output_text = title + str(auth_mean).strip('[]') + ";" + str(com_mean).strip('[]') + ";" + str(aff_mean).strip('[]') + "\n"
output_file = open(output_file_name, 'w')
output_file.write(output_text)
output_file.close()

yields

  Happy New Year;3.00000000e+00   3.80000000e+00   2.90017063e-11   2.22002581e-03
  6.24813011e-02   2.00000000e-02   2.22222222e-03;  1.33333333e+00   5.83333333e+00   2.10396963e-03   9.66994906e-05
  2.48172703e-01   1.89774638e-02   1.25814091e-03   1.48016578e-04; 1.          0.00247191

How can I make a simple straight line like

Happy New Year;3.00000000e+00;3.80000000e+00;2.90017063e-11;2.22002581e-03;6.24813011e-02;2.00000000e-02;2.22222222e-03;1.33333333e+00;5.83333333e+00;2.10396963e-03;9.66994906e-05;2.48172703e-01;1.89774638e-02;1.25814091e-03;1.48016578e-04;1.;0.00247191

Answer 1

I added commas to separate the elements of your three lists (as queried by MERose above), and I also had to initialise output_file_name: output_file_name = "output.csv" .

I hope this isn't a stupid question, but is it possible you are checking the outputted file in a text editor with "word wrap" turned on? I ran the code, and I get a single line of output as you require. If I then view the file in Notepad++ with "word wrap" turned on, it appears to be on multiple lines when actually it is just one line.

FYI: the outputted file also imports nicely into LibreOffice Calc.

Answer 2

First, you forgot commas in your code, I think it is:

title = "Happy New Year"
auth = [  3.00000000e+00,   3.80000000e+00,   2.90017063e-11,   2.22002581e-03,
          6.24813011e-02,   2.00000000e-02,   2.22222222e-03]
aff = [ 1.  ,        0.00247191]
comm = [  1.33333333e+00,   5.83333333e+00,   2.10396963e-03,   9.66994906e-05,
          2.48172703e-01,   1.89774638e-02,   1.25814091e-03,   1.48016578e-04]

Now about the problem: You can merge many arrays into one using itertools chain :

from itertools import chain

out = chain([title], auth, aff, comm, ['\n'])

Then you can join this row by semicolon:

str_row = ';'.join(map(str, out))
print(str_row)  #or write to file, if you need

However, I strongly suggest you not reinvent the wheel and use standard csv module for writing any csv files. You can specify ';' as delimiter when setting up csv writer.