How would I flatten this in Python so that every "widget" is an element of a list?
{ "widgets" :[{"num": "1", "letter": "a",
"widgets" :[{"num": "2", "letter": "b",
"widgets" :[{"num": "3","letter": "c"},
{"num": "4", "letter": "d"}]
}]
}]
}
So it ends up as
[{"num":"1", "letter","a"},
{"num": "2", "letter":"b"},
{"num": "3", "letter":"c"},
{"num": "4", "letter":"d"}]
After you shoot whoever gave you that data, maybe something like this:
def flatten_widgets(widget):
stack = [widget['widgets']]
while stack:
for widget in stack.pop():
yield {k: v for k, v in widget.items() if k != 'widgets'}
if 'widgets' in widget:
stack.append(widget['widgets'])
>>> list(flatten_widgets(a))
[{'letter': 'a', 'num': '1'},
{'letter': 'b', 'num': '2'},
{'letter': 'c', 'num': '3'},
{'letter': 'd', 'num': '4'}]
Here's a recursive solution:
def flatten_widget(widget):
assert isinstance(widget, dict)
# Remove any sub-level widgets for processing
widgets = widget.pop('widgets', None)
# The first object is itself, unless it contains nothing
flat_list = [widget] if widget else []
# If there are sub-level widgets, flatten them
if widgets:
assert isinstance(widgets, list)
# Recursively flatten each widget and add it return list
for w in widgets:
flat_list += flatten_widget(w)
# Return all widgets in a list
return flat_list
print flatten_widget(widget)
# [{'num': '1', 'letter': 'a'}, {'num': '2', 'letter': 'b'}, {'num': '3', 'letter': 'c'}, {'num': '4', 'letter': 'd'}]
Note that it won't detect cycling references. Also it assumes that you don't mind the original data structure would be modified. I haven't benchmarked it but I would guess not having to copy each dict item would be a bit faster.
This was my hasty response; after penning, I realized it doesn't have the list items in the order you specified; however I think this might point you in the right direction vis-a-vis recursion, just as the other answers here have.
Note: did not import python module "elegance". ;)
def getflattenedwidgetlist(thislist):
thislevellist = list()
for dictionary in thislist:
thisdict = dict()
thislevellist.append(thisdict)
for key in dictionary:
if key != "widgets":
thisdict[key] = dictionary[key]
if "widgets" in dictionary:
return getflattenedwidgetlist(dictionary["widgets"]) + [thisdict]
return thislevellist
stuff = {
"widgets" :[{
"num": "1",
"letter": "a",
"widgets" :[{
"num": "2",
"letter": "b",
"widgets" :[{
"num": "3",
"letter": "c"
},
{
"num": "4",
"letter": "d"
}]
}]
}]
}
print getflattenedwidgetlist([stuff])
