[R] Finding the Mean of a Specific Set of Columns

[Eric Berger]

Hi Isaac,
I am sure you will get lots of answers to this. Here is one using the dplyr
package.
Assuming that your data frame is called 'a', then
library(dplyr)
b <- dplyr::group_by(a,plot) %>% dplyr::summarise( mean(lai) )
b
# A tibble: 4 x 2
   plot `mean(lai)`
  <int>       <dbl>
1   104        243.
2   105        212.
3   106        223.
4   108        212

HTH,
Eric



On Thu, Feb 14, 2019 at 6:20 PM Isaac Barnhart <ihb using ksu.edu> wrote:

> I am having trouble finding the mean of a specific part of my dataset.
> Here is a sample of it:
>
> plot lai leaf
> 1 104 82 1
> 2 104 167 2
> 3 104 248 3
> 4 104 343 4
> 5 104 377 5
> 6 105 64 1
> 7 105 139 2
> 8 105 211 3
> 9 105 296 4
> 10 105 348 5
> 11 106 94 1
> 12 106 167 2
> 13 106 243 3
> 14 106 281 4
> 15 106 332 5
> 16 108 83 1
> 17 108 382 2
> 18 108 320 3
> 19 108 146 4
> 20 108 129 5
>
> I have many different plot numbers, none of which follow any kind of
> specific numeric sequence (even though I have sorted them from smallest to
> largest). I need to take the average (mean) of the LAI for each plot, and
> was wondering if there was a way to specify the code to do this. For
> example: I need the average of all the LAI measurements for each leaf of
> plot 104, 105, etc. Any help would be appreciated. Thanks!
>
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