pandas 唯一值unique( )和nunique()

以Kaggle上black Friday数据为例

一，unique（）函数输出每个特征的唯一值

for col in data.columns:
    print('{} unique element : {}'.format(col,data[col].unique()))

输出

User_ID unique element : [1000001 1000002 1000003 ... 1004113 1005391 1001529]
Product_ID unique element : ['P00069042' 'P00248942' 'P00087842' ... 'P00038842' 'P00295642'
 'P00091742']
Gender unique element : ['F' 'M']
Age unique element : ['0-17' '55+' '26-35' '46-50' '51-55' '36-45' '18-25']
Occupation unique element : [10 16 15  7 20  9  1 12 17  0  3  4 11  8 19  2 18  5 14 13  6]
City_Category unique element : ['A' 'C' 'B']
Stay_In_Current_City_Years unique element : ['2' '4+' '3' '1' '0']
Marital_Status unique element : [0 1]
Product_Category_1 unique element : [ 3  1 12  8  5  4  2  6 14 11 13 15  7 16 18 10 17  9]
Product_Category_2 unique element : [ 0.  6. 14.  2.  8. 15. 16. 11.  5.  3.  4. 12.  9. 10. 17. 13.  7. 18.]
Product_Category_3 unique element : [ 0. 14. 17.  5.  4. 16. 15.  8.  9. 13.  6. 12.  3. 18. 11. 10.]
Purchase unique element : [ 8370 15200  1422 ... 14539 11120 18426]

二，nunique() Return number of unique elements in the object.

for col in data.columns:
    print('{} unique element: {}'.format(col,data[col].nunique()))

输出：

User_ID unique element: 5891
Product_ID unique element: 3623
Gender unique element: 2
Age unique element: 7
Occupation unique element: 21
City_Category unique element: 3
Stay_In_Current_City_Years unique element: 5
Marital_Status unique element: 2
Product_Category_1 unique element: 18
Product_Category_2 unique element: 18
Product_Category_3 unique element: 16
Purchase unique element: 17959