python - pandas group by and find first non null value for all columns

Question

I have pandas DF as below ,

id  age   gender  country  sales_year
1   None   M       India    2016
2   23     F       India    2016
1   20     M       India    2015
2   25     F       India    2015
3   30     M       India    2019
4   36     None    India    2019

I want to group by on id, take the latest 1 row as per sales_date with all non null element.

output expected,

id  age   gender  country  sales_year
1   20     M       India    2016
2   23     F       India    2016
3   30     M       India    2019
4   36     None    India    2019

In pyspark,

df = df.withColumn('age', f.first('age', True).over(Window.partitionBy("id").orderBy(df.sales_year.desc())))

But i need same solution in pandas .

EDIT :: This can the case with all the columns. Not just age. I need it to pick up latest non null data(id exist) for all the ids.

Answer 1

Use GroupBy.first:

df1 = df.groupby('id', as_index=False).first()
print (df1)
   id   age gender country  sales_year
0   1  20.0      M   India        2016
1   2  23.0      F   India        2016
2   3  30.0      M   India        2019
3   4  36.0    NaN   India        2019

If column sales_year is not sorted:

df2 = df.sort_values('sales_year', ascending=False).groupby('id', as_index=False).first()
print (df2)
   id   age gender country  sales_year
0   1  20.0      M   India        2016
1   2  23.0      F   India        2016
2   3  30.0      M   India        2019
3   4  36.0    NaN   India        2019