naming dictionaries after list items

Question

I have a list like list = ['foo', 'bar', 'baz'] and am running a for-loop over the items. each time I do so, I'd like to create a dictionary named after the list element currently being looped over. For example

for element in list:
    ('%s' + '_' + 'dict') % element = {}

which, of course, doesn't work, giving me the error:

SyntaxError: can't assign to operator

Any ideas?

Answer 1

While it's possible to use eval or to create new entries in the globals() dictionary, it's almost certainly a bad idea. Instead, use your dictionary names as keys into another dictionary explicitly:

names = ['foo', 'bar', 'baz']

d = {}
for name in names:
    d[name] = {}

You could also use a dict comprehension (or a generator expression in the dict constructor, if you're in an earlier version of Python that doesn't allow dict comprehensions):

d = {name: {} for name in names}
# d = dict((name, {}) for name in names) # generator expression version for pre-2.7

Answer 2

You can do it with a dict. Like:

context = {}
for element in list:
    context['%s_dict' % element] = {}

After that, you can use context['foo_dict'] to access the dictionaries you created.