CODEWITHSUNDEEP
python
Clev3r
Clev3r

Reputation: 1588

Max/Min value of Dictionary of List

I have a dictionary mapping an id_ to a list of data values like so: dic = {id_ : [v1, v2, v3, v4]}. I'm trying to iterate through every value in the dictionary and retrieve the max/min of a certain index of the list mappings.

What I want to do is something like this:

maximum = max([data[0], ??) for id_, data in self.dic.items()])

...but obviously this will not work. Is it possible to do this in one line as above?

Upvotes: 4

Views: 8959

Answers (2)

johnsyweb
johnsyweb

Reputation: 141860

Using a generator expression and max():

In [10]: index = 0

In [11]: dictA = { 1 : [22, 31, 14], 2 : [9, 4, 3], 3 : [77, 15, 23]}

In [12]: max(l[index] for l in dictA.itervalues())
Out[12]: 77

Note: itervalues() returns an iterator over the dictionary’s values without making a copy, and is therefore more efficient than values() (in Python < 3).

Upvotes: 1

Rohit Jain
Rohit Jain

Reputation: 213311

You need to use it something like this:

maximum = max(data[0] for data in dic.values())

since you are not using your keys, simply use dict.values() to get just the values.

Upvotes: 9

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