Numpy is not saving csv properly

Question

I have a simple numpy array made of floats and integers

array_to_save=np.array([shutter_time,int(nb_frames),np.mean(intensities),np.std(intensities)])

I would like to save this numpy array, appending it to an existing csv file by doing the following.

    with open('frames_stats.csv','a') as csvfile:
     
        np.savetxt(csvfile,array_to_save,delimiter=',')

However, it saves this array not as an ordinary csv file, where there were supposed to be 4 values separated by commas, but it saves each value as a new line of the file such as follows:

5.000000000000000000e-01 1.495000000000000000e+03 2.340000000000000000e+02 0.000000000000000000e+00 5.000000000000000000e-01 1.495000000000000000e+03 2.340000000000000000e+02 0.000000000000000000e+00

How can I save such a csv file properly?

You need to add more info. What are the values. What was the csv like before you append the new values? — Eirini Kotzia
– Eirini Kotzia, Commented Nov 18, 2022 at 16:09

adem daradour · Accepted Answer · 2022-11-18 16:15:57Z

2

Use pandas DataFrame append and DataFrame to_csv

https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.append.html https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.to_csv.html

answered Nov 18, 2022 at 16:15

adem daradour

535 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Serge Ballesta · Accepted Answer · 2022-11-18 16:39:39Z

1

You could simply reshape your array to change you 1D array of dimension 4 to a 2D array of dimensions (1, 4):

with open('frames_stats.csv','a') as csvfile:
    np.savetxt(csvfile,array_to_save.reshape((1, 4)),delimiter=',')

answered Nov 18, 2022 at 16:39

Serge Ballesta

150k13 gold badges137 silver badges267 bronze badges

Comments

wrbp · Accepted Answer · 2022-11-18 16:31:34Z

1

You are saving a one dimension array (1 column) but you are expecting the result of a 2 dimensions array with one line, so in order to have the desired result do this

array_to_save=np.array([[shutter_time,int(nb_frames),np.mean(intensities),np.std(intensities)]])

see the double square brackets

edited Nov 18, 2022 at 16:31

answered Nov 18, 2022 at 16:30

wrbp

8901 gold badge5 silver badges10 bronze badges

Collectives™ on Stack Overflow

Numpy is not saving csv properly

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related