Write an array of differing lengths to a csv in python

Question

I'm trying to write a large number of fields from a Class to a csv. E.g.

for i in range(0,  len(t)):
    t.writerow([t[i].a,  t[i].b,  t[i].c,...]

However I have a subclass which I also want to write at the end of this list:

for i in range(0,  len(t)):
    t.writerow([  t[i].a,  t[i].b,  t[i].c,...  t[i].z[0].s,  t[i].z[1].s ...])

However I'm not sure how I achieve this, the subclasses are of varying lengths, so how would I ensure that each row just appends the relevant number of subclasses at the end? I can't find anything in the documentation about it. Do I make a string out of the subclass entries, and then just paste one entry at the end? Thanks.

It's very hard to read your sample code, please add some whitespace to make it more obvious where the things begin and end. Oh, and three dots ... is sufficient. Thanks. — martineau
– martineau, Commented Dec 2, 2012 at 0:08

martineau · Accepted Answer · 2012-12-02 00:23:51Z

1

I think writing it something like this would work:

for i in range(len(t)):
    row = [[ e.a, e.b, e.c, ...] + [e.z[0], e.z[1], e.z[2], ...] for e in t[i]]
    t.writerow(row)

answered Dec 2, 2012 at 0:23

martineau

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1 Comment

eamon1234 Over a year ago

thanks, I had gone and made an empty list and appended with a for loop , but that looks a lot nicer!

Martijn Pieters · Accepted Answer · 2012-12-01 23:51:49Z

1

If z is just a python list, just append it to the list of fields from t:

t.writerow([t[i].a, t[i].b, t[i].c, ...] + t[i].z)

which would be the same as [one, list] + [another, list].

It looks like you can just loop over t (a list) itself instead of using a range():

for item in t:
    t.writerow([item.a, item.b, item.c, ...] + item.z)

answered Dec 1, 2012 at 23:51

Martijn Pieters

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2 Comments

eamon1234 Over a year ago

Thanks Martijn. It's not quite a list. It's a subclass as in t.z[1].s, t.z[2].s.... I tried what you suggested but that didn't work. That was my fault, I've edited the OP

eamon1234 Over a year ago

I could make t.z.s into a list though and then add it?

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