I've got a list of Tokens which looks something like:
[{
Value: "Blah",
StartOffset: 0,
EndOffset: 4
}, ... ]
What I want to do is get a count of how many times each value occurs in the list of tokens.
In VB.Net I'd do something like...
Tokens = Tokens.
GroupBy(Function(x) x.Value).
Select(Function(g) New With {
.Value = g.Key,
.Count = g.Count})
What's the equivalent in Python?
IIUC, you can use collections.Counter:
>>> from collections import Counter
>>> tokens = [{"Value": "Blah", "SO": 0}, {"Value": "zoom", "SO": 5}, {"Value": "Blah", "SO": 2}, {"Value": "Blah", "SO": 3}]
>>> Counter(tok['Value'] for tok in tokens)
Counter({'Blah': 3, 'zoom': 1})
if you only need a count. If you want them grouped by the value, you could use itertools.groupby and something like:
>>> from itertools import groupby
>>> def keyfn(x):
return x['Value']
...
>>> [(k, list(g)) for k,g in groupby(sorted(tokens, key=keyfn), keyfn)]
[('Blah', [{'SO': 0, 'Value': 'Blah'}, {'SO': 2, 'Value': 'Blah'}, {'SO': 3, 'Value': 'Blah'}]), ('zoom', [{'SO': 5, 'Value': 'zoom'}])]
although it's a little trickier because groupby requires the grouped terms to be contiguous, and so you have to sort by the key first.
Let's assume that is your python list, containing dictionnaries:
my_list = [{'Value': 'Blah',
'StartOffset': 0,
'EndOffset': 4},
{'Value': 'oqwij',
'StartOffset': 13,
'EndOffset': 98},
{'Value': 'Blah',
'StartOffset': 6,
'EndOffset': 18}]
A one liner:
len([i for i in a if i['Value'] == 'Blah']) # returns 2
import collections
# example token list
tokens = [{'Value':'Blah', 'Start':0}, {'Value':'BlahBlah'}]
count=collections.Counter([d['Value'] for d in tokens])
print count
shows
Counter({'BlahBlah': 1, 'Blah': 1})
token = [{
'Value': "Blah",
'StartOffset': 0,
'EndOffset': 4
}, ... ]
value_counter = {}
for t in token:
v = t['Value']
if v not in value_counter:
value_counter[v] = 0
value_counter[v] += 1
print value_counter
Another efficient way is to convert data to Pandas DataFrame and then aggregate them. Like this:
import pandas as pd
df = pd.DataFrame(data)
df.groupby('key')['value'].count()
df.groupby('key')['value'].sum()
