dataframe count unique code example

Example 1: count unique pandas

df['column'].nunique()

Example 2: unique values in dataframe column count

df.groupby('mID').agg(['count', 'size', 'nunique']).stack()


             dID  hID  uID
mID                       
A   count      5    5    5
    size       5    5    5
    nunique    3    5    5
B   count      2    2    2
    size       2    2    2
    nunique    2    2    2
C   count      1    1    1
    size       1    1    1
    nunique    1    1    1

Example 3: count how many unique rows a DataFrame has

df = pd.DataFrame(np.random.randint(0,2,size = (10,3)))
df
	0	1	2
0	1	1	1
1	1	0	1
2	1	1	1
3	1	0	0
4	1	1	1
5	1	0	1
6	0	0	1
7	0	1	1
8	0	1	0
9	0	0	1
# the only unique rows are : 3, 7 and 8
df.duplicated(keep = False) == False
0    False
1    False
2    False
3     True
4    False
5    False
6    False
7     True
8     True
9    False
dtype: bool
# so to count how many unique rows we have: 
sum(df.duplicated(keep = False) = False)
3