merge() result incorrect (NAs) when `by` column contains non-ASCII characters
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Assessment
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Newbie friendliness
- 35/100
Research direction
Start by reproducing the supplied merge() example with the reported R 3.3.3 and locale details, then trace the merge() implementation and existing tests for character-key matching. Done means the example returns the expected row for 他 without regressing other merge behavior, with a regression test covering the non-ASCII key.
Written by the indexing model from the issue text.
Description
When the by column contains non-ASCII characters (e.g, Chinese), the merge() function returns NA unexpectedly.
d1=data.table(a=c("你", "我", "a", "他"), b=1:4)
d2=data.table(a=c("我", "他", "a"), c=3:5)
merge(d1, d2, by="a", all.x=TRUE, sort=FALSE)
should return
a b c
1 你 1 NA
2 我 2 3
3 a 3 5
4 他 4 4
right?
but actually turns out to be:
a b c
1: 你 1 NA
2: 我 2 3
3: a 3 5
4: 他 4 NA
Could you look into this problem?
> sessionInfo()
R version 3.3.3 (2017-03-06)
Platform: i386-w64-mingw32/i386 (32-bit)
Running under: Windows 7 (build 7601) Service Pack 1
locale:
[1] LC_COLLATE=English_United States.1252 LC_CTYPE=Chinese (Simplified)_People's Republic of China.936
[3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C
[5] LC_TIME=English_United States.1252
attached base packages:
[1] compiler stats graphics grDevices utils datasets methods base
other attached packages:
[1] data.table_1.10.4
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