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

[Ben Tupper]

Hi,

You might try your hand at the tidyverse collection of tools which are veddy nice for this kind of wrangling. https://www.tidyverse.org/

Does this do the trick?

## START
library(readr)
library(dplyr)

txt <- "row 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"

x <- readr::read_delim(txt, delim = " ") %>%
	dplyr::group_by(plot) %>%
	dplyr::summarize(mean_lai = mean(lai))
	
x
# A tibble: 4 x 2
   # plot mean_lai
  # <dbl>    <dbl>
# 1   104     243.
# 2   105     212.
# 3   106     223.
# 4   108     212 

## END
 
Cheers,
Ben

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> On Feb 14, 2019, at 9:31 AM, 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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Ben Tupper
Bigelow Laboratory for Ocean Sciences
60 Bigelow Drive, P.O. Box 380
East Boothbay, Maine 04544
http://www.bigelow.org

Ecological Forecasting: https://eco.bigelow.org/