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I need to sort a dictionary by first, values with reverse=True, and for repeating values, sort by keys, reverse=False
So far, I have this
dict = [('B', 3), ('A', 2), ('A', 1), ('I', 1), ('J', 1)] sorted(dict.items(), key=lambda x: (x[1],x[1]), reverse=True) which returns...
[('B', 3), ('A', 2), ('J', 1), ('I', 1), ('A', 1)] but I need it to be:
[('B', 3), ('A', 2), ('A', 1), ('I', 1), ('J', 1)] as you can see, when values are equal, I can only sort the key in a decreasing fashion as specified... But how can I get them to sort in an increasing fashion?
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In python, if you want to sort a list of tuples by the second element then we have the function called sort() and by using lambda function as a key function. A custom comparator is a key function in sort().
Sort tuples Passing a tuple to sorted() returns a sorted list. To convert a list to a tuple, use tuple() . You can write in one line. If you want to sort in descending order, set the argument reverse to True .
In Python, you can reverse the items of lists ( list ) with using reverse() , reversed() , and slicing. If you want to reverse strings ( str ) and tuples ( tuple ), use reversed() or slice.
sort(reverse=True) will sort it in reverse order. If the list is already sorted, it will sort it in reverse order (i.e. reverse it) - but will likely take longer than list.
The following works with your input:
d = [('B', 3), ('A', 2), ('A', 1), ('I', 1), ('J', 1)] sorted(d,key=lambda x:(-x[1],x[0])) Since your "values" are numeric, you can easily reverse the sort order by changing the sign.
In other words, this sort puts things in order by value (-x[1]) (the negative sign puts big numbers first) and then for numbers which are the same, it orders according to key (x[0]).
If your values can't so easily be "negated" to put big items first, an easy work-around is to sort twice:
from operator import itemgetter d.sort(key=itemgetter(0)) d.sort(key=itemgetter(1),reverse=True) which works because python's sorting is stable.
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In [4]: l = [('B', 3), ('A', 2), ('A', 1), ('I', 1), ('J', 1)] In [5]: sorted(l, key=lambda (x,y):(-y,x)) Out[5]: [('B', 3), ('A', 2), ('A', 1), ('I', 1), ('J', 1)] If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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