How to write a csv from a numpy.ndarray?

Question

data = [[1 2 3 4][5 6 7 8][9 10 11 12]]

The object I receive has this structure. The numbers in each sub-array aren't separated

I've tried to convert into a list and then split it but it writes separated rows

simMatrix = open(ficheroDestino, 'w', newline='') with simMatrix: writer = csv.writer(simMatrix,delimiter=',') for x in range (0,len(data)): result = data[x].tolist() writer.writerow(result)

Other code:

                                 simMatrix = open(ficheroDestino, 'w',newline='')
                                 with simMatrix:
                                 writer = csv.writer(simMatrix,delimiter=',')
                                 for x in range (0,len(data)):
                                     result = data[x].tolist()
                                     result2 = ' '.join(str(e) for e in datos)
                                     result3 = datos2.split(" ")
                                     writer.writerow(result3)

I expect the output of my csv as: 1 2 3 4

5 6 7 8

8 10 11 12

each number in a different column and row

what do you mean by the numbers in each sub-array aren't separated. What's the shape of data array ? — Pavan Kumar Polavarapu
– Pavan Kumar Polavarapu, Commented Sep 5, 2019 at 23:46
its just one item like [1 2 3 4 ] for example: data[0] = [1 2 3 4] as one item, I want to separate this numbers llike [1, 2, 3, 4] and write it in a csv — Federico
– Federico, Commented Sep 5, 2019 at 23:49

Pavan Kumar Polavarapu · Accepted Answer · 2019-09-06 00:02:14Z

1

I would use Pandas DataFrame to_csv method. Following is a sample

import numpy as np
import pandas as pd

data = [["1 2 3 4"], ["5 6 7 8"], ["9 10 11 12"]]
pd.DataFrame(np.array([str(i).replace("['", "").replace("']", "").split(" ") for i in data])).to_csv("file.csv")

answered Sep 6, 2019 at 0:02

Pavan Kumar Polavarapu

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ToughMind · Accepted Answer · 2019-09-06 02:11:58Z

1

You can just try numpy.savetxt(), example code is as below:

import numpy as np

data = np.array([[1, 2, 3, 4],
                 [5, 6, 7, 8],
                 [9, 10, 11, 12]]).astype(int)

np.savetxt('test.csv', data, fmt='%d', delimiter=' ')

The .csv file will be like:

1 2 3 4
5 6 7 8
9 10 11 12

edited Sep 6, 2019 at 2:11

answered Sep 6, 2019 at 2:02

ToughMind

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Don Quixote · Accepted Answer · 2019-09-05 23:55:40Z

0

How about this.

    import pandas as pd
    data = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
    datas = pd.DataFrame(data)

    print(datas)
    datas.to_csv('./test.csv',index=False)

answered Sep 5, 2019 at 23:55

Don Quixote

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1 Comment

Federico Over a year ago

i tried this and it writes all in the first column for the row 1, for example row 1 and column 2 its empty

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