melt doc fixes (#7400)

* typo of

* nzchar() for consistency with vignette

* switch ifelse yes no

---------

Co-authored-by: Toby Dylan Hocking <[email protected]>

Author: tdhock

man/measure.Rd

@@ -83,7 +83,7 @@ melt(who, measure.vars = measure(diagnosis, gender, ages, pattern="new_?(.*)_(.)
 print(melt(who, measure.vars = measure(
   diagnosis, gender, ages,
   ymin=as.numeric,
-  ymax=function(y)ifelse(y=="", Inf, as.numeric(y)),
+  ymax=function(y)ifelse(nzchar(y), as.numeric(y), Inf),
   pattern="new_?(.*)_(.)(([0-9]{2})([0-9]{0,2}))"
 )), class=TRUE)
 }

vignettes/datatable-reshape.Rmd

@@ -279,7 +279,7 @@ melt(who, measure.vars = measure(
 
 When using the `pattern` argument, it must be a Perl-compatible
 regular expression containing the same number of capture groups
-(parenthesized sub-expressions) as the number other arguments (group
+(parenthesized sub-expressions) as the number of other arguments (group
 names). The code below shows how to use a more complex regex with five
 groups, two numeric output columns, and an anonymous type conversion
 function,