Databases
StackOverflow2013
Postsdbo
POweighted averages of paired observations in R
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POweighted averages of paired observations in R
    primarykey
    data
    text
    <p>Yesterday I posted a question asking how to obtain averages of observations in neighboring columns of a data set:</p> <p><a href="https://stackoverflow.com/questions/13739243/average-pairs-of-columns-in-r">average pairs of columns in R</a></p> <p>Today I realized I actually need weighted averages. I tried modifying the answer above to the revised situation, but still do not understand the family of apply functions well enough to do so easily.</p> <p>I have written code to obtain weighted averages for an example data set below and can probably use that code with my real data. Nevertheless, if someone is able to illustrate how to use the apply family of functions here for weighted averages, that will go a long way, I think, toward improving my understanding and coding proficiency. Regardless, thank you for all past and future help and ideas.</p> <pre><code>x = read.table(text = " site yr1 yr2 yr3 yr4 1 10 15 6 8 2 10 20 30 40 3 5 NA 2 3 4 100 100 NA NA", sep = "", header = TRUE) x weights = read.table(text = " site yr1 yr2 yr3 yr4 1 2 4 1 3 2 2 2 4 2 3 3 2 2 3 4 4 2 2 4", sep = "", header = TRUE) weights x.weights = x * weights numerator &lt;- matrix(NA, ncol=((ncol(x.weights)/2)+1), nrow=nrow(x.weights)) for(i in 1: ((ncol(weights)-1)/2)) { for(j in 1: nrow(weights) ) { numerator[j, 1 ] &lt;- x[j,1] numerator[j,(i+1)] &lt;- sum(c(x.weights[j,(1 + ((i-1)*2 + 1))], x.weights[j,(1 + ((i-1)*2 + 2))]), na.rm = TRUE) } } numerator denominator &lt;- matrix(NA, ncol=((ncol(weights)/2)+1), nrow=nrow(weights)) for(i in 1: ((ncol(weights)-1)/2)) { for(j in 1: nrow(weights) ) { denominator[j, 1 ] &lt;- x[j,1] denominator[j,(i+1)] &lt;- sum(c(weights[j,(1 + ((i-1)*2 + 1))], weights[j,(1 + ((i-1)*2 + 2))]), na.rm = TRUE) } } denominator weighted.ave &lt;- numerator[,2:ncol(numerator)] / denominator[,2:ncol(denominator)] weighted.ave # insert value from x if one of a pair is missing # insert NA if both in a pair are missing adj.weighted.ave &lt;- weighted.ave for(i in 1: ((ncol(x)-1)/2)) { for(j in 1: nrow(x) ) { if( is.na(x[j,(1 + (i-1)*2 + 1)]) &amp; !is.na(x[j,(1 + (i-1)*2 + 2)])) adj.weighted.ave[j,i] = sum(c(x[j,(1 + ((i-1)*2 + 1))], x[j,(1 + ((i-1)*2 + 2))]), na.rm = TRUE) if(!is.na(x[j,(1 + (i-1)*2 + 1)]) &amp; is.na(x[j,(1 + (i-1)*2 + 2)])) adj.weighted.ave[j,i] = sum(c(x[j,(1 + ((i-1)*2 + 1))], x[j,(1 + ((i-1)*2 + 2))]), na.rm = TRUE) if( is.na(x[j,(1 + (i-1)*2 + 1)]) &amp; is.na(x[j,(1 + (i-1)*2 + 2)])) adj.weighted.ave[j,i] = NA } } adj.weighted.ave # [,1] [,2] # [1,] 13.33333 7.50000 # [2,] 15.00000 33.33333 # [3,] 5.00000 2.60000 # [4,] 100.00000 NA </code></pre>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USCommunity
    1. USMark Miller
    plurals
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POweighted averages of paired observations in R
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThe `weighted.mean` function computes weighted averages; you should be able to pass that into whichever apply function and then pass the `w` argument (the weights) as an additional argument (where the three dots are in *apply's argument list).
      singulars
      1. POweighted averages of paired observations in R
      1. USGlen_b
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload