fix to [.data.frame for duplicate column names

git-svn-id: https://svn.r-project.org/R/trunk@41492 00db46b3-68df-0310-9c12-caf00c1e9a41
wch · May 8, 2007 · 4566410 · 4566410
1 parent 875a21d
commit 4566410
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diff --git a/NEWS b/NEWS
@@ -293,6 +293,9 @@ BUG FIXES
 
     o	rbind() failed if the only data frame had 0 rows. (PR#9657)
 
+    o	<a data.frame>[i, j] could sometimes select the wrong column
+	when j is numeric if there are duplicate column names.
+
 
 
 		CHANGES IN R VERSION 2.5.0

diff --git a/src/library/base/R/dataframe.R b/src/library/base/R/dataframe.R
@@ -510,7 +510,9 @@ data.frame <-
         x <- x[j]
         cols <- names(x)  # also needed for 'drop'
         if(any(is.na(cols))) stop("undefined columns selected")
-        sxx <- match(cols, names(xx))
+        ## sxx <- match(cols, names(xx)) fails with duplicate names
+        nxx <- structure(seq_along(xx), names=names(xx))
+        sxx <- match(nxx[j], seq_along(xx))
     } else sxx <- seq_along(x)
 
     rows <- NULL # placeholder: only create row names when needed