如何找到数据帧特定列值的不同计数

Question

df:

Field1 Field2
1      2
3      4
5      6
1      7
3      8

Please let me know how to find distinct count of df['Field1'], Results should be 3 In SQL we use query like this.

select count(distinct Field1) as Field1DistCount from df

Answer 1

Let's use nunique :

df['Field1'].nunique()

Output:

3

Answer 2

I'm assuming you are using pandas?

import pandas as pd
print(df['COLUMN_NAME_HERE'].nunique())

If you want a dataframe of the unique values you could do ( and here is a good link to go along with it ):

print(df['COLUMN_NAME_HERE'].unique())

And if you want the counts of those unique values using value_counts :

print(df['COLUMN_NAME_HERE'].value_counts())

Answer 3

You can even use value_counts() to get the count of unique values for a particular value present in a column.

Example :

df['col_name'].value_counts().values #This will fetch you the count

And if you want to store the unique values in another column then you can execute the below command :

df['col_name'].value_counts().index

Let me know if this helps. Thanks