How to write multiple matrices to a text file in python?

Question

I have a for loop creating a matrix every time and I need to write all the matrices to a text file

I used np.savetxt()in the for loop, but in the end, the textfile only shows the last matrix I created.

Does anyone know what happened?

file = open("newfile.txt", "w")
for i in range (0,5):
    matrix = numpy.zeros((5, 5)) 
    np.savetxt(file, matrix)
file.close()

Possible duplicate of How do you append to a file in Python? — Bamcclur
– Bamcclur, Commented Nov 8, 2016 at 20:01

Haifeng Zhang · Accepted Answer · 2016-11-08 19:57:12Z

1

You need use ba other than w when you append a numpy array into a csv file. b is binary mode Without b your code will have type error. Tested on python3.5

answered Nov 8, 2016 at 19:57

Haifeng Zhang

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damores · Accepted Answer · 2016-11-08 19:49:51Z

0

You have to open the file in append mode:

file = open("newfile.txt", "a")

answered Nov 8, 2016 at 19:49

damores

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Ada Borowa · Accepted Answer · 2016-11-08 19:50:42Z

0

Flag "w" causes file to be overwitten, you should use "a", for appending.

answered Nov 8, 2016 at 19:50

Ada Borowa

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