Question

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How to read logical data from a file in R

I generated a file which contains a logical value either a “TRUE” or a “FALSE” on each line. Now I would like to read the logical data from the file into R. However the data that are read in are of mode “character” not logical values. I was wondering how to read the data as logical values from the file.

My R code is

cat(FALSE,"\n", file="1.txt", append=FALSE);
for (i in 2:5) cat(TRUE,"\n",file="1.txt", append=TRUE);
a=scan(file="1.txt", what="logical")

The output is:

> mode(a)
1] "character"
> mode(a[1])
[1] "character"
> a[1]
[1] "FALSE"

I want a[1] to be logical value.

Thanks and regards!

Answer 1

Instead of:

a=scan(file="1.txt", what="logical")

try:

a = scan(file="1.txt", what=logical(0))

See ?scan for documentation.