Python csv writer, numpy array to csv

Question

I have Python dict containing 4 key value pairs. Each value is a numpy arrays. Now I want to print the whole dict to a csv, forcing to write one numpy array per row.

with open(os.path.join("csv", title), 'w', newline='') as f:
  w = csv.DictWriter(f, list(data.keys()))
  w.writeheader()
  w.writerow(data)

Is what I have used yet. But some of my arrays get written to several rows instead of a single line.

Here an example of input data:

{'DE': array([[ 38574. , 38538.1904, 39511.6190, 42521.1428, 50586. , 46282.5238, 42714.4761, 40612.0476], [ 42798.4666, 42112.5333, 42277.8666, 42886.1333, 50224.3333, 48148.8 , 44272.6666, 41210.2 ]])}

I expect the output so that, each line of my array is written on one line. Instead I get a file containing "\n" after a certain amount of digits. how can i force to write the whole array in one row?

sorry for that, i edited and hopefully this should answer the questions — Flo
– Flo, Commented Aug 9, 2014 at 14:33
your first example is not correct, Dictwriter writes each column based on the keys, the output should be in separate columns not one below the other — Padraic Cunningham
– Padraic Cunningham, Commented Aug 9, 2014 at 14:43

Padraic Cunningham · Accepted Answer · 2014-08-09 15:04:42Z

1

DE has a multidimensional array as its value, Inter has an empty list as its value, you end up with two columns one with Inter as the header with an empty list in its column and a second column DE with the array in its column which is exactly what the code should be doing.

If you want to alter each array length try setting numpy.set_printoptions:

numpy.set_printoptions(linewidth=1000)

edited Aug 9, 2014 at 15:04

answered Aug 9, 2014 at 14:51

Padraic Cunningham

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2 Comments

Flo Over a year ago

Yes and no. I end up with the following file opened in excel: A1: DE, INTER, A2: 38574, 38538, 39511, 42521, A3: 48751, 54737, 58725, 60445, A4: 50586, 46282, 42714, 40612] and if i open it with the editor it shows me the "\n" after 4 values. and i don't know where they come from.

Flo Over a year ago

actually it is still not working as intended. Sometimes when i open the csv in excel everything is written to one cell and sometimes it is written as expected.

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