Reading a file into R with partly unknown filename

Question

Is there a way to read a file into R where I do not know the complete file name. Something like.

read.csv("abc_*")

In this case I do not know the complete file name after abc_

Answer 1

If you have exactly one file matching your criteria, you can do it like this:

read.csv(dir(pattern='^abc_')[1])

If there is more than one file, this approach would just use the first hit. In a more elaborated version you could loop over all matches and append them to one dataframe or something like that.

Note that the pattern uses regular expressions and thus is a bit different from what you did expect (and what I wrongly assumed at my first shot to answer the question). Details can be found using ?regex

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If you have a directory you want to submit, you have do modify the dir command accordingly:

read.csv(dir('path/to/your/file', full.names=T, pattern="^abc"))

The submitted path in your case may be c:\\users\\user\\desktop, and then the pattern as above. full.names=T forces dir() to output a whole path and not only the file name. Try running dir(...) without the read.csv to understand what is happening there.

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If you want to give your path as a complete string, it again gets a bit more complicated:

filepath <- 'path/to/your/file/abc_'
read.csv(dir(dirname(filepath), full.names=T, pattern=paste("^", basename(filepath), sep='')))

That process will fail if your filename contains any regular expression keywords. You would have to substitute then with their corresponding escape sequences upfront. But that again is another topic.