CODEWITHSUNDEEP
pandasnumpyunique
dfjdlf
dfjdlf

Reputation: 47

count of unique values in pandas dataframe column

I am trying to find the frequency of unique values in a column of a pandas dataframe I know how to get the unique values like this: 

data_file.visiting_states()

returns : 

array(['CA', 'VA', 'MT', nan, 'CO', 'CT'],    dtype=object)

and I want to return the count of those unique values and I know I cant do .value_counts() because its a numpy array

Upvotes: 1

Views: 1493

Answers (1)

jezrael
jezrael

Reputation: 863501

You can use nunique:

data_file = pd.DataFrame({'visiting_states':['CA', 'VA', 'MT', np.nan, 'CO', 'CT','CA',
                                             'VA', 'MT', np.nan, 'CO', 'CT']})
print (data_file)
   visiting_states
0               CA
1               VA
2               MT
3              NaN
4               CO
5               CT
6               CA
7               VA
8               MT
9              NaN
10              CO
11              CT

print (data_file.visiting_states.nunique())
5

print (data_file.visiting_states.nunique(dropna=False))
6

arr = np.array(['CA', 'VA', 'MT', np.nan, 'CO', 'CT'],    dtype=object)
print (arr)
['CA' 'VA' 'MT' nan 'CO' 'CT']

print (len(arr))
6

Upvotes: 1

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