CODEWITHSUNDEEP
routputindentation
groebsgr
groebsgr

Reputation: 131

R indent output

is it possible to indent output in R?

e.g.

cat("text1\n")

indent.switch(indent=4)
cat("random text\n")
print("another random text")
indent.switch(indent=0)

cat("text2\n")

resulting in 

text1
    random text
    another random text
text2

I searched for this a few months ago, found nothing and am now searching again.

My current idea is to "overwrite" (I forgot the special term) the functions cat and/or print with an additional argument like:

cat("random text", indent=4)

Only I'm stuck with this and I dont like this procedure very much. Any ideas?

Edit: I should be more particular, nevertheless thank you for the \t (omg, i totally forgot this -.-) and that I can format it inside cat. The given solutions work, but only solve my second-choice-path. A switch as shown in my first codeexample does not exist I suppose?

My problem is that I have parts of a bigger program which have multiple subscripts, and the output of each subscript should be indented. This is absolutely possible with the "\t" or just blanks inside cat() but has to be done in every command, which I dont like very much.

Solution

I used Chris C's code and extended it in a very easy way. (Thank you very much Chris!)

define.catt <- function(ntab = NULL, nspace=NULL){
    catt <- function(input = NULL){
        if(!is.null(ntab)) cat(paste0(paste(rep("\t", ntab), collapse = ""), input))
        if(!is.null(nspace)) cat(paste0(paste(rep(" ", nspace), collapse = ""), input))
        if(is.null(ntab) && is.null(nspace)) cat(input)
    }
    return(catt)
}

Upvotes: 1

Views: 5153

Answers (2)

marQIsoftGuy
marQIsoftGuy

Reputation: 81

You may consider the very versatile function capture.output(...), which evaluates the '...' list of expressions provided as main input arguments, and stores the text output (as if it would be displayed in the console) into a character vector instead. Then, you simply have to modify the strings as desired: here you want to add some leading spaces to each string. Finally, you write the strings to the console.

These can be done all in one line of nested calls. For example:

writeLines(paste("  ", capture.output(print(head(iris))), sep=""))

I therefore recommend you all to read the help of the capture.output function, and then try to use it for various purposes. Indeed, since the main input has the usual flexibility of the '...' list-like structure, you are free to include, for instance, a call to one home-made function, and thus do almost anything. As for indentation, that is simply done with paste function, once the former has done its magic.

Upvotes: 1

Chris C
Chris C

Reputation: 1655

The same way you used \n to print a newline, you can use \t to print a tab.

E.g.

cat("Parent level \n \t Child level \n \t \t Double Child \n \t Child \n Parent level")

Evaluates to 

Parent level 
     Child level 
         Double Child 
     Child 
 Parent level

As an alternative, you can create a derivative of cat called catt and alter options depending on the script. For example.

define.catt <- function(ntab = NULL){
    catt <- function(input = NULL){
        cat(paste0(paste(rep("\t", ntab), collapse = ""), input))
    }
    return(catt)
}

You would then set catt with however many tabs you wanted by 

catt <- define.catt(ntab = 1)
catt("hi")
    hi
catt <- define.catt(ntab = 2)
catt("hi")
        hi

And just use catt() instead of cat().

Upvotes: 2

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