[R] Merging two columns of unequal length

[William Michels]

You should review "The Recycling Rule in R" before attempting to
perform functions on 2 or more vectors of unequal lengths:

https://cran.r-project.org/doc/manuals/R-intro.html#The-recycling-rule

Most often, the "Recycling Rule" does exactly what the researcher
intends (automatically). And in many cases, performing functions on
data of unequal (or not evenly divisible) lengths is either 1) an
indication of problems with the input data, or 2) an indication that
the researcher is unnecessarily 'forcing' data into a rectangular data
structure, when another approach might be better (e.g. the use of the
tapply function).

However, if you see no other way, the functions "cbind.na" and/or
"rbind.na" available from Andrej-Nikolai Spiess perform binding of
vectors without recycling:

http://www.dr-spiess.de/Rscripts.html

All you have to do is download and source the correct R-script, and
call the function:

> cbind(1:5, 1:2)
     [,1] [,2]
[1,]    1    1
[2,]    2    2
[3,]    3    1
[4,]    4    2
[5,]    5    1

Warning message:
In cbind(1:5, 1:2) :
  number of rows of result is not a multiple of vector length (arg 2)

> source("/Users/myhomedirectory/Downloads/cbind.na.R")
> cbind.na(1:5, 1:2)
     [,1] [,2]
[1,]    1    1
[2,]    2    2
[3,]    3   NA
[4,]    4   NA
[5,]    5   NA
>

This issue arises so often, Dr. Spiess's two scripts "rbind.na" and
"cbind.na" have my vote for inclusion into the base-R distribution.

Best of luck,

W Michels, Ph.D.


On Mon, Dec 12, 2016 at 3:41 PM, Bailey Hewitt <bailster at hotmail.com> wrote:
>
> Dear R Help,
>
>
> I am trying to put together two columns of unequal length in a data frame. Unfortunately, so far I have been unsuccessful in the functions I have tried (such as cbind). The code I am currently using is : (I have highlighted the code that is not working)
>
>
> y<- mydata[,2:75]
>
> year <- mydata$Year
>
> res <- data.frame()
>
> for (i in 1:74){
>
>   y.val <- y[,i]
>
>   lake.lm= lm(y.val ~ year)
>
>   lake.res=residuals(lake.lm)
>
>   new.res <- data.frame(lake.res=lake.res)
>
>   colnames(new.res) <- colnames(y)[i]
>
> #cbind doesn't work because of the unequal lengths of my data columns
>
>   res <- cbind(res, new.res)
>
>   print(res)
>
> }
>
>
> mydata is a csv file with "Year" from 1950 on as my first column and then each proceeding column has a lake name and a day of year (single number) in each row.
>
>
> Please let me know if there is any more information I can provide as I am new to emailing in this list. Thank you for your time!
>
>
> Bailey Hewitt
>
>         [[alternative HTML version deleted]]
>
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