New submission from Abraham Smith:
Some students were working on matrix routines for practice.
The following code:
L = [ [0]*3 ]*3
for i in range(3):
...for j in range(3):
...if i==j: L[i][j]=1
was expected to return
[[1,0,0],[0,1,0],[0,0,1]]
but it returned
[[1,1,1],[1,1,1
Abraham Smith added the comment:
(Obviously, there's a copy/paste mistake in the second case; it should read
map(id, M).)
--
___
Python tracker rep...@bugs.python.org
http://bugs.python.org/issue23406
Abraham Smith added the comment:
Thanks for the helpful responses and correcting my misunderstanding.
Regarding improved documentation, I see now that the table at
https://docs.python.org/2/library/stdtypes.html#id2 indeed says shallow
copies; however, the footnote seems to bury the lede
