Question

Given the following data structure:

out = {
  'foo': { 'public':{}, 'private':{}, 'other':{} },
  'bar': { 'public':{}, 'private':{}, 'other':{} }
}

I am attempting to slice out parts of the sub-structure to create a new dict. My use for this is to respond to requests with all data except that marked private.

To do the opposite is trivial:

response = {x,y['private'] for x,y in out.iteritems()}

Which constructs a dict for each foo and bar containing only the data marked private. But is there some functionality in the standard library (itertools perhaps) that would produce the following:

out = {
  'foo': { 'public':{}, 'other':{} },
  'bar': { 'public':{}, 'other':{} }
}

I have tried the following:

{x:(y['public'], y['other']) for x,y in out.iteritems()}

Although I would prefer to not use a tuple, and not explicitly name each sub-structure, as this is not reusable or scalable.

def remove(name, obj):
    return {x:y for x,y in obj.iteritems() if x is not name}
{x:remove('private',y) for x,y in out.iteritems()}

This seems to work, but is there a better way? Any ideas?

Answer 1

You can break this down into parts; you want a new dictionary which has some parts removed. So create a function which can return a dictionary without the elements in question and call this is part of an iterator.

You’re using dictionary comprehensions so something like this would work:

def remove_items(d, *items):
    """
    Return dictionary copy with some items removed.
    """
    return { a: b for a, b in d.iteritems() if a not in items }

print { x: remove_items(y, 'private') for x, y in out.iteritems() }