Add column to display the value of each unique column value, repeated for all instances of that value in Pandas

In pandas, I would like to add a new column which displays the value for an elements type, repeated for all instances of that element (couldn’t figure out a better way to describe this).

For example, in the below, there is a Type called "La". I want to create a new column called "La". In the case of element "A", for each record, the value 9 should show under the LA column. For "B", it would be 2.

My Data:

Element     Type  Value
A           Ex     5
A           La     9
A           Bd     0
B           La     2 
B           Ex     7 
B           Ex     3

What I want:

Element     Type  Value  La
A           Ex     5     9
A           La     9     9
A           Bd     0     9
B           La     2     2
B           Ex     7     2
B           Ex     3     2

EDIT: For the value I’m looking at (La), there won’t ever be duplicates. Just one per element.

>Solution :

For only "La" and assuming there are no duplicates, filter and map:

df['La'] = df['Element'].map(df.loc[df['Type'].eq('La')]
                               .set_index('Element')['Value']
                             )

Output:

  Element Type  Value  La
0       A   Ex      5   9
1       A   La      9   9
2       A   Bd      0   9
3       B   La      2   2
4       B   Ex      7   2
5       B   Ex      3   2

If you want all Elements, use a pivot_table and merge (here keeping the max value in case of duplicates, but you can aggregate with any function):

df.merge(df.pivot_table(index='Element', columns='Type', values='Value',
                        aggfunc='max', fill_value=-1).reset_index(),
         on='Element', how='left')

Output:

  Element Type  Value  Bd  Ex  La
0       A   Ex      5   0   5   9
1       A   La      9   0   5   9
2       A   Bd      0   0   5   9
3       B   La      2  -1   7   2
4       B   Ex      7  -1   7   2
5       B   Ex      3  -1   7   2