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I have a folder, which contains 70 files (in .xls format). I would like to write a script in R, which makes plot from every .xls file and saves it to separate .jpg (or .png) files. Is it possible? Give me a hint?

svlasov
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monika_w091
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1 Answers1

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Something like this should work: 

library(readxl)
fn <- list.files("yourfolder", pattern = "xlsx?$", full.names = T)
dfs <- lapply(fn, read_excel)
for (x in 1:length(dfs)) {
  png(paste0(fn[x], ".png"))
  with(dfs[[x]], {
    plot(...)
  })
  dev.off()
}
lukeA
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  • Can the `for` loop be replaced with `lapply`? – Brian P Apr 02 '15 at 12:45
  • I guess it can be replaced, but why should it? – lukeA Apr 02 '15 at 12:49
  • I have a problem with: " dfs <- lapply(fn, read_excel) " because object "fn" I have from the previous line, but what is it "read_excel" ? And I don't have library "readxl" ( I cant find this library in Rstudio to install it), so library "xlsx" will be ok? :) – monika_w091 Apr 02 '15 at 13:03
  • Have a look at [readxl](https://github.com/hadley/readxl): you prly need `install.packages("devtools"); devtools::install_github("hadley/readxl")`. – lukeA Apr 02 '15 at 13:07
  • @lukeA Still learning R, and regularly hear that `for` loops should generally be avoided. – Brian P Apr 02 '15 at 13:40
  • I have already installed package :) and I have question. When I write ggplot function I must point out data source ( ggplot(data ......... ) ) . I dont have idea what I should write in this place. And another question. :) Before I make plots I have to prepare my data and for this purpose I use function "melt" (from reshape package). How Can I put this in code? – monika_w091 Apr 02 '15 at 14:21
  • For ggplot, use `dfs[[x]]` as data argument. The rest: I dunno, because I don't know your data. Feel free to edit your original question and add it. Make sure to read http://adv-r.had.co.nz/Reproducibility.html and http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example before you post/edit. – lukeA Apr 02 '15 at 14:32