Keeping duplicate values and trying pivot-CodePudding

I have a CSV file that has various repeating elements. Below is an example of the table.

id     code  date
314asre B1  20201010
343asr  B2  20200405
150ase  B1  20210615
314asre B1  20210506
343asr  B3  20220408

I want to create something like this:

id	B1	B2	B3
314asre	20201010	NULL	NULL
343asr	NULL	20200405	NULL
150ase	20210615	NULL	NULL
314asre	20210506	NULL	NULL
343asr	NULL	NULL	20220408

I tried using pivot and pivot table, but I got an error saying duplicate values in the index for the pivot, and pivot_table removes the duplicate values completely. I want to keep the duplicate values as shown in the above table. Any help will be appreciated.

Code I have tried:

df.pivot_table(index='id' , columns = 'code' , values= 'date')
df.reset_index(inplace=True)

CodePudding user response：

Make pivot table with random index and change index to id column as follows.

df['temp'] = range(len(df))

result = df.pivot_table(index= 'temp', columns = 'code' , values= 'date')
result.index = df['id']
result

the result is as follows.

code    B1  B2  B3
id          
314asre 20201010.0  NaN NaN
343asr  NaN 20200405.0  NaN
150ase  20210615.0  NaN NaN
314asre 20210506.0  NaN NaN
343asr  NaN NaN 20220408.0