Hi all,

 

I have a dataframe of the following type:

 

Day        Place     dendrometer    max

1              1                              1              4684

2              1                              1              4831

..

1              1                              2              2486

2              1                              2              2596

.

1              2                              1              6987

2              2                              1              6824

 

I need  the first element of each dendrometer  as NA, so every time R
calculates "max" for a new dendrometer (independently of the place), starts
with NA,  like this:

 

Day        Place     dendrometer    max

1              1                              1              NA

2              1                              1              4831

..

1              1                              2              NA

2              1                              2              2596

.

1              2                              1              NA

2              2                              1              6824

                                

Could you also let me know I could calculate MEAN of the max column for each
dendrometer within each ring (sapply, aggregate?) instead of calculating
mean for the entire max column?



Thanks!

 


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