列表中的Python访问和字典值求和

Question

I would like to know how can I access list values in a dictionary to sum them:

{'key1': [3, 1], 'key2': [0, 4], 'key3': [57492, 204652], 'key4': [1,3]}

I would like to sum the first element of each list sum(3,0,57492,1).

Is it possible to do so without any loop ?

Thank you in advance

Answer 1

You have to iterate over the entire dictionary which means you have to use loop.

It can simply be done with a list comprehension like:

sum([values[0] for key, values in dictionary.items()])

If the number of items in the dictionary are large in number then instead of dictionary.items() you can use a generator function

For Python 2.x:

for key, value in d.iteritems():

For Python 3.x:

for key, value in d.items():

You can read more on how to do list comprehension here: Link

Iterating over a dictionary: Link