Currently sub(perl=TRUE) allows you to specify \U and \L
in the replacement argument so that the rest of the subpatterns
in the line (the \\<digit> things) will be converted to upper
or lower case, respectively. perl also also has a \E operator
to end these case conversions for the rest of the subpatterns
(so they retain whatever case they had in the original text).
For symmetry's sake I think it would be nice if R supported that
also. E.g., to capitalize the first and last letters of every
word, leaving the case of the interior letters alone, could be
done with:
> gsub("(\\w)(\\w*)(\\w)", "\\U\\1\\E\\2\\U\\3", "useRs may fly into JFK
or laGuardia", perl=TRUE)
[1] "UseRS MaY FlY IntO JFK OR LaGuardiA"
> sub("(\\w)(\\w*)(\\w)", "\\U\\1\\E\\2\\U\\3", "useRs may fly into JFK
or laGuardia", perl=TRUE)
[1] "UseRS may fly into JFK or laGuardia"
A question regarding this came up in r-help today.
Bill Dunlap
TIBCO Software Inc - Spotfire Division
wdunlap tibco.com
Index: src/library/base/man/grep.Rd
===================================================================
--- src/library/base/man/grep.Rd (revision 48319)
+++ src/library/base/man/grep.Rd (working copy)
@@ -73,7 +73,7 @@
\code{"\\9"} to parenthesized subexpressions of \code{pattern}.
For
\code{perl = TRUE} only, it can also contain \code{"\\U"} or
\code{"\\L"} to convert the rest of the replacement to upper or
- lower case.
+ lower case, or \code{"\\E"} to end such case conversion.
}
}
\details{
Index: src/main/pcre.c
===================================================================
--- src/main/pcre.c (revision 48319)
+++ src/main/pcre.c (working copy)
@@ -90,6 +90,9 @@
} else if (p[1] == 'L') {
p++; n -= 2;
upper = FALSE; lower = TRUE;
+ } else if (p[1] == 'E') { /* end case modification */
+ p++; n -= 2;
+ upper = FALSE; lower = FALSE;
} else if (p[1] == 0) {
/* can't escape the final '\0' */
n--;
@@ -168,6 +171,9 @@
} else if (p[1] == 'L') {
p += 2;
upper = FALSE; lower = TRUE;
+ } else if (p[1] == 'E') { /* end case modification */
+ p += 2;
+ upper = FALSE; lower = FALSE;
} else if (p[1] == 0) {
p += 1;
} else {
Index: src/library/base/man/grep.Rd
===================================================================
--- src/library/base/man/grep.Rd (revision 48319)
+++ src/library/base/man/grep.Rd (working copy)
@@ -73,7 +73,7 @@
\code{"\\9"} to parenthesized subexpressions of \code{pattern}. For
\code{perl = TRUE} only, it can also contain \code{"\\U"} or
\code{"\\L"} to convert the rest of the replacement to upper or
- lower case.
+ lower case, or \code{"\\E"} to end such case conversion.
}
}
\details{
Index: src/main/pcre.c
===================================================================
--- src/main/pcre.c (revision 48319)
+++ src/main/pcre.c (working copy)
@@ -90,6 +90,9 @@
} else if (p[1] == 'L') {
p++; n -= 2;
upper = FALSE; lower = TRUE;
+ } else if (p[1] == 'E') { /* end case modification */
+ p++; n -= 2;
+ upper = FALSE; lower = FALSE;
} else if (p[1] == 0) {
/* can't escape the final '\0' */
n--;
@@ -168,6 +171,9 @@
} else if (p[1] == 'L') {
p += 2;
upper = FALSE; lower = TRUE;
+ } else if (p[1] == 'E') { /* end case modification */
+ p += 2;
+ upper = FALSE; lower = FALSE;
} else if (p[1] == 0) {
p += 1;
} else {
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