Replacing Values with average if possible

["Bert Jacobs" <b.jacobs@pandora.be>]

Hi,

I have a dataframe that looks like this

Col A   Col B           Col C
1               200             F
2               300             T       
3               250             F
4               600             T
5               300             F       
6               500             T

Now I would like to have the following result
Col A   Col B           Col C           Col D
1               200             F               200
2               300             T               225 (average of 200 and 250)
3               250             F               250
4               600             T               275 (average of 250 and 300)

5               300             F               300
6               500             T               300 (last value with F)

OR

Col A   Col B           Col C
1               200             T
2               300             F       
3               250             F
4               600             T
5               300             T       
6               500             F

Now I would like to have the following result
Col A   Col B           Col C           Col D
1               200             T               300 (first value with F in
Col C)
2               300             F               225 
3               250             F               250
4               600             T               375 (average of 250 and 500)

5               300             T               375 (average of 250 and 500)
6               500             F               500 

Is this possible with an easy command?

Thx for your suggestions,
Bert