how to add new tuple as key in dictionary?

[John Gordon]

In <344c23f8-f440-4c23-a5e6-9f93b0145e02 at googlegroups.com> Ho Yeung Lee <jobmattcon at gmail.com> writes:

> I find that list can not be key in dictionary
> then find tuple can be as key

> but when I add new tuple as key , got error in python 2.7

> groupkey = {(0,0): []}
> groupkey[tuple([0,3])] = groupkey[tuple([0,3])] + [[0,1]]

The right-hand side of your expression is rightly complaining that
groupkey[(0,3)] doesn't exist.

Would you expect to say

    a = a + 1

When a doesn't exist?  Your code tries to do much the same thing.

-- 
John Gordon                   A is for Amy, who fell down the stairs
gordon at panix.com              B is for Basil, assaulted by bears
                                -- Edward Gorey, "The Gashlycrumb Tinies"