How to replace existing csv files by exporting new numpy arrays in python

Question

I want to export numpy arrays as csv files but I may have files with the same names in my folder. So, I want to replace old files with new ones. I am using the following method:

arr=np.array([[1., 2.], [2., 1.]])
np.savetxt('arr.csv', arr, delimiter=',')

But this method overwrites rows of the existing arr.csv file in my folder. Is there a way to completely replace the old file? I do appreciate any help in advance.

Dear @Corralien, the difference is that my previous csv file may have 10 rows. Then new one may have only 8 rows. this method will rewrite the first 8 rows of old one and two last rows will remain there. I I could replace the file, then the problem of that two extra rows will be solved. — Link_tester
– Link_tester, Commented Jul 20, 2021 at 9:12

Corralien · Accepted Answer · 2021-07-20 09:20:06Z

1

np.savetxt (numpy=='1.20.3') overwrites the whole file:

arr = np.random.random((3, 2))
np.savetxt('arr.csv', arr, delimiter=',')

>>> %cat arr.csv
2.123431629646361785e-01,6.914800473216878851e-01
9.544549349895192769e-01,6.749508363116073495e-01
2.238126343800779239e-01,3.919697864527211806e-01

arr = np.random.random((1, 2))
np.savetxt('arr.csv', arr, delimiter=',')

>>> %cat arr.csv
4.355318781801621464e-01,4.574856378543381563e-01

answered Jul 20, 2021 at 9:20

Corralien

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