[R] [R Code] Split long names in format.ftable

[Leonard Mada]

Dear List members,


I wrote some code to split long names in format.ftable. I hope it will 
be useful to others as well.


Ideally, this code should be implemented natively in R. I will provide 
in the 2nd part of the mail a concept how to actually implement the code 
in R. This may be interesting to R-devel as well.


### Helper function

# Split the actual names

split.names = function(names, extend=0, justify="Right", blank.rm=FALSE, 
split.ch = "\n", detailed=TRUE) {
     justify = if(is.null(justify)) 0 else pmatch(justify, c("Left", 
"Right"));
     str = strsplit(names, split.ch);
     if(blank.rm) str = lapply(str, function(s) s[nchar(s) > 0]);
     nr  = max(sapply(str, function(s) length(s)));
     nch = lapply(str, function(s) max(nchar(s)));
     chf = function(nch) paste0(rep(" ", nch), collapse="");
     ch0 = sapply(nch, chf);
     mx  = matrix(rep(ch0, each=nr), nrow=nr, ncol=length(names));
     for(nc in seq(length(names))) {
         n = length(str[[nc]]);
         # Justifying
         s = sapply(seq(n), function(nr) paste0(rep(" ", nch[[nc]] - 
nchar(str[[nc]][nr])), collapse=""));
         s = if(justify == 2) paste0(s, str[[nc]]) else 
paste0(str[[nc]], s);
         mx[seq(nr + 1 - length(str[[nc]]), nr) , nc] = s;
     }
     if(extend > 0) {
         mx = cbind(mx, matrix("", nr=nr, ncol=extend));
     }
     if(detailed) attr(mx, "nchar") = unlist(nch);
     return(mx);
}

### ftable with name splitting
# - this code should be ideally integrated inside format.ftable;
ftable2 = function(ftbl, print=TRUE, quote=FALSE, ...) {
     ftbl2 = format(ftbl, quote=quote, ...);
     row.vars = names(attr(ftbl, "row.vars"))
     nr = length(row.vars);
     nms = split.names(row.vars, extend = ncol(ftbl2) - nr);
     ftbl2 = rbind(ftbl2[1,], nms, ftbl2[-c(1,2),]);
     # TODO: update width of factor labels;
     # - new width available in attr(nms, "nchar");
     if(print) {
         cat(t(ftbl2), sep = c(rep(" ", ncol(ftbl2) - 1), "\n"))
     }
     invisible(ftbl2);
}

I have uploaded this code also on Github:

https://github.com/discoleo/R/blob/master/Stat/Tools.Data.R


B.) Detailed Concept
# - I am ignoring any variants;
# - the splitting is actually done in format.ftable;
# - we set only an attribute in ftable;
ftable = function(..., split.ch="\n") {
    [...]
    attr(ftbl, "split.ch") = split.ch; # set an attribute "split.ch"
    return(ftbl);
}

format.ftable(ftbl, ..., split.ch) {
if(is.missing(split.ch)) {
    # check if the split.ch attribute is set and use it;
} else {
    # use the explicitly provided split.ch: if( ! is.null(split.ch))
}
    [...]
}


C.) split.names Function

This function may be useful in other locations as well, particularly to 
split names/labels used in axes and legends in various plots. But I do 
not have much knowledge of the graphics engine in R.


Sincerely,


Leonard