Re: [R] Assigning several lists to variables whose names are contained in other variables

Rui Barradas Sat, 10 Apr 2021 00:02:07 -0700

Hello,

I believe that the point we are missing is that datatable$column storesthe *names* of the graphs, not the graph objects themselves. So in theloop the objects must be retrieved with mget() or get().


First create a reproducible example.



library(tidygraph)

my_function <- function(g){
  stopifnot(inherits(g, "igraph"))
  g %>% mutate(centrality = centrality_pagerank())
}

MYSUBNET1 <- create_notable('bull')
iris_clust <- hclust(dist(iris[1:4]))
MYSUBNET2 <- as_tbl_graph(iris_clust)
MYSUBNET3 <- play_smallworld(1, 100, 3, 0.05)

datatable <- data.frame(column = paste0("MYSUBNET", 1:3))



Now apply the function above to each of the "tbl_graph" objects.

1. Get all objects and apply the function in one instruction. Thenassign the new names.



result <- lapply(mget(datatable$column, envir = .GlobalEnv), my_function)
names(result) <- paste("subnet", datatable$column, sep = "_")

2. Loop through the column with lapply, getting one object and applyingthe function one at a time. Then assign the new names.




result2 <- lapply(datatable$column, function(net_name){
  NET <- get(net_name, envir = .GlobalEnv)
  my_function(NET)
})
names(result2) <- paste("subnet", datatable$column, sep = "_")

3. Loop through the column with a for loop, getting one object andapplying the function one at a time. Then assign the new names.




result3 <- vector("list", length = nrow(datatable))
for(i in seq_along(datatable$column)){
  net_name <- datatable$column[i]
  NET <- get(net_name, envir = .GlobalEnv)
  result3[[i]] <- my_function(NET)
}
names(result3) <- paste("subnet", datatable$column, sep = "_")



4. Now check that all 3 solutions give the same result.


identical(result, result2)
#[1] TRUE
identical(result, result3)
#[1] TRUE


Is this it?

Rui Barradas


Às 17:23 de 09/04/21, Wolfgang Grond escreveu:

As I wrote before, I calculate tbl_graph objects, which will be joined 
afterwards. Not too much, the number of graphs to calculate is in the range 
between 5 to 20.

Further steps are not automated, because they depend on how the single graphs 
look like, and which of them will be joined.

For this reason I thought it would be nice to have the single tbl_ graph 
objects stored in variables having the name of the graph.

For this reason I tried to find a better solution instead of assigning each 
graph by hand:

subnet_MYSUBNET <- my_function(MYSUBNET)

To my understanding it is therefore neccessary to assign the result of the 
function to a variable whose name consists of a fixed string and the content of 
a further variable.

That was the intention for me to ask.

Am 9. April 2021 17:22:05 MESZ schrieb David Winsemius <dwinsem...@comcast.net>:


On 4/9/21 5:21 AM, Wolfgang Grond wrote:

Greg,

here I get the error message:

Error my_function(val) :

cannot find function my_function.


I'm guessing that you are following someone else's blog and have failed

one of two things:

- understand that what was meant by the author was that you were
assumed
to have a function in mind to use for a programming strategy being
illustrated

- or you were copying and pasting only part of a blog and failed to
paste in the code from above where there was earlier code defining
`my_function`


Am 9. April 2021 12:35:40 MESZ schrieb Greg Minshall

<minsh...@umich.edu>:

Wolfgang,

result <- assign(paste("subnet_",  val, sep = "")

result <- my_function(val)

i don't understand why you are twice assigning to =result=.  also,

the

first assignment doesn't seem well formatted (t's missing a value?).

did you mean something like

: assign(paste("subnet_",  val, sep = ""), my_function(val))

(which i would think should work)?

cheers, Greg

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Numberland - Dr. Wolfgang Grond
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and provide commented, minimal, self-contained, reproducible code.


______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
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Re: [R] Assigning several lists to variables whose names are contained in other variables

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