python garbage collection about list append itself

Question

a = [2]
a.append(a)

And I print a,

[2, [...]]

Also I print a[1][0]

What is [...] ? and when I print a[1][0], print 2, not [...] ?

`[...]` means that it's a list but the `print` not displaying its content. — iFlo, Jan 13 '17 at 09:22
good question, but I'm puzzled about the title. What's to do with garbage collection? — Jean-François Fabre, Jan 13 '17 at 09:29
I am watching Python Tutorial, garbage collection youtube, that code is in there. so I think that code is related to garbage collection — li tain, Jan 13 '17 at 09:32

Jean-François Fabre · Accepted Answer · 2017-01-13T09:36:38.967

7

... is the ellipsis object. Here it is issued because else it would print forever! (due to infinite recursion)

and: print(a[1][0]):

a[1] is a so a[1][0] is 2, like a[1][1][1][1][0] is 2 too.

edited Jan 13 '17 at 09:36

answered Jan 13 '17 at 09:23

I just edited. Ellipsis operator is something else. I'll use your link. and it's _not_ pedantic. Thank you very much. – Jean-François Fabre Jan 13 '17 at 09:26
Thanks ! and, It means [2, [2, [2, [2, ~ ]], is it right? – li tain Jan 13 '17 at 09:29
A bit like the larsen you'd get when you're filming your own TV while feeding your image to it :) Actually it means "there are other things but I cannot show them". But it could be issued in other situations. – Jean-François Fabre Jan 13 '17 at 09:30

score 2 · Answer 2 · answered Jan 13 '17 at 09:24

2

Ellipsis ... is used for slicing multidimensional numpy arrays.

The ellipsis syntax may be used to indicate selecting in full any remaining unspecified dimensions.

a[1] is [2, [...]]

so, a[1][0] is 2.

answered Jan 13 '17 at 09:24

Saurav Sahu

2 Answers2