Saving 3 dimensional array to a file in Python

Question

I want to save a 3 dimensional arrays values to a txt or csv file in python. dCx, dCy

I used:

numpy.savetxt('C:/Users/musa/Desktop/LOCO_All_tests/FODO_Example/AllQ/dCx.csv',dCx,delimiter=',')
numpy.savetxt('C:/Users/musa/Desktop/LOCO_All_tests/FODO_Example/AllQ/dCy.csv',dCy,delimiter=',')

And to load it again:

dCx = numpy.genfromtxt('C:/Users/musa/Desktop/LOCO_All_tests/FODO_Example/AllQ/dCx.csv', delimiter=',')
dCy = numpy.genfromtxt('C:/Users/musa/Desktop/LOCO_All_tests/FODO_Example/AllQ/dCy.csv', delimiter=',')

But i got the error massage

"Expected 1D or 2D array, got 3D array instead"

Si i wanted to change the 3d arrays first to 2 arrays and then save it to the files, and when uploaded again i convert it back to 3d for example:

dCx2 = np.array(dCx).reshape(np.array(dCx).shape[0], -1)
dCy2 = np.array(dCy).reshape(np.array(dCy).shape[0], -1)

and after loaded to variable named dCx3 and dCy3 i used:

dCx = np.array(dCx3).reshape(
    np.array(dCx3).shape[0], np.array(dCx3).shape[1] // np.array(dCx).shape[2], np.array(dCx).shape[2])

#dCy = np.array(dCy3).reshape(
#    np.array(dCy3).shape[0], np.array(dCy3).shape[1] // np.array(dCy).shape[2], np.array(dCy).shape[2])

I am looking for a better method that i can used in the saving the 3d arrays to file, or a method to convert the 2d into 3d without having to measure the original arrays every time as it is used in this line:

 np.array(dCy).shape[2], np.array(dCy).shape[2])

The CSV format is inherently tabular format; it is not suitable for three dimensional data. — 9769953
– 9769953, Commented Aug 30, 2022 at 14:43
Are you doing anything with the files in between saving them to disk, and reading them back into memory/NumPy again? — 9769953
– 9769953, Commented Aug 30, 2022 at 14:43
Why not use numpy.save(filepath, data) and data = numpy.load(filepath)? These are binary file formats, and generic for any type of NumPy data. — 9769953
– 9769953, Commented Aug 30, 2022 at 14:56

9769953 · Accepted Answer · 2022-08-30 15:19:35Z

2

Use numpy.save(filepath, data) and data = numpy.load(filepath).

These are binary file formats, and generic for any type of NumPy data

answered Aug 30, 2022 at 15:19

9769953

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NSVR · Accepted Answer · 2022-08-30 14:47:35Z

0

Try tofile. it works for in my case. but array will write in 1D

import numpy as np
arr=np.arange(0,21).reshape(7,3)
arr.tofile('file.txt',sep=',')
arr2=np.fromfile('file.txt',sep=',')

answered Aug 30, 2022 at 14:47

NSVR

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2 Comments

ely66 Over a year ago

it works but as you mentioned the arrays will return in 1 D so still the same problem

NSVR Over a year ago

in that case iterate over every row, and append to the file.\n import numpy as np arr=np.arange(0,21).reshape(7,3) print(arr) for i in arr: with open('file.txt','a') as fp: fp.write(str(i)) fp.write("\n")

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