count number of different values in column dataframe code example

Example 1: get count of unique values in column pandas

df = df.groupby('domain')['ID'].nunique()

print (df)
domain
'facebook.com'    1
'google.com'      1
'twitter.com'     2
'vk.com'          3
Name: ID, dtype: int64

Example 2: python - count how many unique in a column

df['var_1'].nunique()   # How many unque values are present in a variable