for.loop with WAV files

Question

I'm trying to create a loop for reading in stereo wave files in R, but I'm unsure if I should use for.loop or while.loop. I'm calculating the RMS for both channels.

Here's the action for one sound file:

foo=readWave("mysound.wav")
L=foo@left
R=foo@right
rms(L)
rms(R)

Now, I have directories full of 2 minute sound files. I want to take each of those files, isolate the channels, and calculate the RMS. I THINK this is how it's done:

mydir=list.files("directory", recursive=TRUE) 
for (i in 1:length(mydir)) {
    foo=readWave(mydir[i])
    L=foo@left
    R=foo@right
    rms(L)
    rms(R)
    write(combine, file="test.txt", append=true, sep="\t")  
}

This loop returns the error message that my first sound files doesn't exist. As per the suggestion below, I've also tried to read in the files by:

wav_files <- lapply(mydir, readWave)
Error in FUN(c("DASBR2_20131112$224708.wav", "DASBR2_20131112$224910.wav",  : 
   File 'DASBR2_20131112$224708.wav' does not exist.

This also returns that my file does not exist. Perhaps there is a better way to read in the wave files? Can lapply or for.loop handle waves?

When I type mydir into the console, R produces the following output:

> mydir
   [1] "DASBR2_20131112$224708.wav" "DASBR2_20131112$224910.wav"
   [3] "DASBR2_20131112$225110.wav" "DASBR2_20131112$225310.wav"
   [5] "DASBR2_20131112$225446.wav" "DASBR2_20131112$225648.wav"
   ...

This is what I expect, as these are the names of my sound files. Thoughts?

Welcome to stackoverflow! Looking at your profile reveals that you've asked a few of questions, but you haven't voted on or accepted any of the answers you've received. Maybe take a look at [this link regarding what to do when someone answers your question](http://meta.stackoverflow.com/help/someone-answers) — Jota, Feb 04 '14 at 02:30
What is the output when you enter `mydir` into your R console? Is it the file names or file paths you expect? This is kind of blind troubleshooting for me. lapply(mydir, readWave) on my machine when my expected vector of file names is stored in mydir. — Jota, Feb 04 '14 at 03:55

score 2 · Answer 1 · answered Feb 04 '14 at 18:44

2

I think you might just need to get the full path to the files from the current directory.

mydir <- list.files("directory", recursive=TRUE, full.names=TRUE)

Alternatively, you could change directories after the list.files but before reading them.

setwd("directory")

answered Feb 04 '14 at 18:44

Aaron left Stack Overflow

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Okay! Setting the full.names=TRUE seemed to fix the initial issue! Thank you Aaron! However, now I'm running out of memory, and I've already maxed out the settings. :( One issue fixed, another arises.... – etgriffiths Feb 04 '14 at 21:26

score 1 · Answer 2 · edited Dec 11 '21 at 15:12

1

My first thought is to use lapply to read in the files. Something along the lines of this:

wav_files <- lapply(mydir, readWave)

Then I would go through the resulting list of Wave objects using lapply to accomplish the remaining parts of the task.

Something like this could work for extracting channels and using the rms function:

right_rms <- lapply(wave_files, function(x)rms(x@right))

edited Dec 11 '21 at 15:12

Nimantha

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answered Feb 04 '14 at 00:26

Jota

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Oh! Like create the function separately rather than running a loop function? – etgriffiths Feb 04 '14 at 18:35
Thank you, Frank. I'm going to try your second suggestion after I fix my memory problem. – etgriffiths Feb 04 '14 at 21:28

score 1 · Accepted Answer · edited Dec 11 '21 at 15:04

Here is how I did this:

fnam=file.path("directory path")
filist=list.files(fnam, recursive=TRUE, pattern="wav")
filist1=paste(fnam, "/", filist, sep="")
nfiles=length(filist1)
test_rms=c("Full File Path", "RMS-L","RMS-R")
for (i in 1:nfiles){
     inname=filist1[i]
     ywave=readWave(inname)
     L=ywave@left
     R=ywave@right
     test_rms = rbind(test_rms, c(inname, rms(L), rms(R)))
 }

The code for RMS can be replaced with whatever process you need to preform. I will say that the code failed to run through my entire directory, as I had may sub-directories. At least two deep from the path I specified. This code went one level in, and read everything in that directory, even wav files in further sub-directories. I think this script just can handle two directories out.

for.loop with WAV files

3 Answers3

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