Open files with variable filenames

Question

I read a matlab file with the R.matlab package and get a number from it as a list. I turn it into a numeric:

library(R.matlab)

# simple case: static filename

setwd("C:/Files/Fold")
nc <- readMat('passvar1.mat')

nC <- as.numeric(nc)
nC
## 10

More complex cast: I need to open file in folder in R with nC in name: C:/Files/Coordinates/CoordsRS%nC%.md.txt

All files have same name apart from number, for example:

 C:/Files/Coordinates/CoordsR4.md.txt
 C:/Files/Coordinates/CoordsR10.md.txt

and, I need to apply operation to this file contents (i.e. pass in a parameter to readMat so it can read them dynamically)

Answer 1

It should be easiest to build the file names either with a paste0 or sprintf call. For example

nC <- 10
paste0("C:/Files/Coordinates/CoordsR", nC, ".md.txt")
# [1] "C:/Files/Coordinates/CoordsR10.md.txt"
sprintf("C:/Files/Coordinates/CoordsR%d.md.txt",nC)
# [1] "C:/Files/Coordinates/CoordsR10.md.txt"

sprintf() has many more options when it comes to padding with leading zeros or otherwise formatting the number before inserting into the string. You can then pass these filenames to readMat()