Python Revision - Section XI - Advanced Modules
Counter
Counter is a dict subclass which helps count hashable objects. Inside of its elements are stored as dictionary keys and the counts of the objects are stored as the value.
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from collections import Counter
lst = [1,2,2,3,1,4,4,5,5]
Counter(lst)
#Counter({1: 2, 2: 2, 4: 2, 5: 2, 3: 1})
The Counter wors with any kind of lists and also with strings. There are some methods that makes Counter more useful:
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sum(c.values()) # total of all counts
c.clear() # reset all counts
list(c) # list unique elements
set(c) # convert to a set
dict(c) # convert to a regular dictionary
c.items() # convert to a list of (elem, cnt) pairs
c.most_common() # get the most common elements
c += Counter() # remove zero and negative counts
defaultdict
It’s a dictionary-like object which takes a first argument as a default data type and will never raise a KeyError.
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from collections import defaultdict
d = defaultdict(object) # object can be an int, or a string, any object
We can even initialize the dictionary with default values:
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d = defaultdict(lambda: 0)
OrderedDict
It’s a dictionary subclass that remembers the order in which its contents are added.
Python Debugger
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import pdb
x = [1,2,4]
pdb.set_trace()
a = x[4]
The execution will stop where the command pdb.set_trace() is written and we can use ‘q’ to quit. For further details, click here!
I hope it will be helpful to you and if there’s any questions or something else, please, feel free to contact me.
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