From 330dee6f6a8def7901b6169572ba23afd2afbd4f Mon Sep 17 00:00:00 2001
From: arunsrinivasan <aragorn168b@gmail.com>
Date: Thu, 17 Dec 2015 11:42:24 +0100
Subject: [PATCH] Better fix fread's check.names using make.names, #1027.

---
 R/fread.R             | 3 ++-
 README.md             | 2 ++
 inst/tests/tests.Rraw | 9 +++++----
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/R/fread.R b/R/fread.R
index 2c801048bd..21f48f5dee 100644
--- a/R/fread.R
+++ b/R/fread.R
@@ -97,8 +97,9 @@ fread <- function(input="",sep="auto",sep2="auto",nrows=-1L,header="auto",na.str
     } else {
         setattr(ans, "class", "data.frame")
     }
+    # #1027, make.unique -> make.names as spotted by @DavidArenberg
     if (isTRUE(as.logical(check.names))) {
-        setattr(ans, 'names', make.unique(names(ans)))
+        setattr(ans, 'names', make.names(names(ans), unique=TRUE))
     }
     as_factor <- function(x) {
         lev = forderv(x, retGrp = TRUE, na.last = NA)
diff --git a/README.md b/README.md
index 38c8f2eed3..f9c1bced30 100644
--- a/README.md
+++ b/README.md
@@ -95,6 +95,8 @@
 
   6. `dim.data.table` is now implemented in C. Thanks to Andrey Riabushenko.
 
+  7. Better fix to `fread`'s `check.names` argument using `make.names()`, [#1027](https://github.com/Rdatatable/data.table/issues/1027). Thanks to @DavidArenberg for spotting the issue with the previous fix using `make.unique()`.
+
 ### Changes in v1.9.6  (on CRAN 19 Sep 2015)
 
 #### NEW FEATURES
diff --git a/inst/tests/tests.Rraw b/inst/tests/tests.Rraw
index d66f873943..9a78bcfce5 100644
--- a/inst/tests/tests.Rraw
+++ b/inst/tests/tests.Rraw
@@ -6490,11 +6490,12 @@ text = "x,y\n1,a\n2,a\n3,b\n4,b\n5,a\n"
 test(1527.3, dt[, y := factor(y)], fread(text, stringsAsFactors=TRUE))
 
 # #1027, check.names argument to fread
-nm1 = names(data.table(a=1:2, a=3:4))
+nm1 = names(fread("a,a\n1,2\n3,4", check.names=FALSE))
 nm2 = names(fread("a,a\n1,2\n3,4", check.names=TRUE))
-nm3 = names(fread("a,a\n1,2\n3,4", check.names=FALSE))
-test(1528.1, make.unique(nm1), nm2)
-test(1528.2, nm1, nm3)
+nm3 = names(fread("a b,a b\n1,2\n3,4", check.names=TRUE))
+test(1528.1, c("a", "a"), nm1)
+test(1528.2, c("a", "a.1"), nm2)
+test(1528.3, c("a.b", "a.b.1"), nm3)
 
 # add tests for between
 x = sample(10, 20, TRUE)