Python Dataframe Binary Encoding

Question

I have a dataframe that looks like this:

User	Product
1	a
1	b
2	a
2	c
3	b

I want 1 row per user with the products as columns where it gives a 1 or 0 if the user purchased the product or not, how can I do this?

Answer 1

What you are looking for is "cross tabulation" or simply crosstab. Pandas has pd.crosstab for the same.

pd.crosstab(df['User'], df['Product'])

Product  a  b  c
User            
1        1  1  0
2        1  0  1
3        0  1  0

Answer 2

df.pivot_table(index="User", columns="Product", aggfunc=len).fillna(0)

# Result:

Product    a    b    c
User                  
1        1.0  1.0  0.0
2        1.0  0.0  1.0
3        0.0  1.0  0.0