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[R-Forge #5585] DT[, list(list(.)), by=.] returns wrong results in R-3.1.0. #481

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arunsrinivasan opened this Issue Jun 8, 2014 · 1 comment

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arunsrinivasan commented Jun 8, 2014

Submitted by: Arun ; Assigned to: Nobody; R-Forge link

require(data.table)
DT <- data.table(x=c(1,2,2,3,3,3), y=10:15)
DT[, print(list(list(.I))), by=x] ## prints fine.
# [[1]]
# [[1]][[1]]
# [1] 1
# 
# [[1]]
# [[1]][[1]]
# [1] 2 3
# 
# [[1]]
# [[1]][[1]]
# [1] 4 5 6
# 
# Empty data.table (0 rows) of 1 col: x

DT[, list(list(.I)), by=x] ## all points to last grouping variable
#    x    V1
#1: 1 4,5,6
#2: 2 4,5,6
#3: 3 4,5,6

The issue goes away if . is wrapped with I(.) or any other function for that matter.

## works fine.
DT[, list(list(I(.I))), by=x]
DT[, list(list(sum(y))), by=x]

@arunsrinivasan arunsrinivasan changed the title from [R-Forge #5585] DT[, list(list(.)), by=.] returns wrong results in R-3.1.0. to [R-Forge #5585] `DT[, list(list(.)), by=.]` returns wrong results in R-3.1.0. Jun 9, 2014

@arunsrinivasan arunsrinivasan changed the title from [R-Forge #5585] `DT[, list(list(.)), by=.]` returns wrong results in R-3.1.0. to [R-Forge #5585] DT[, list(list(.)), by=.] returns wrong results in R-3.1.0. Jun 9, 2014

@arunsrinivasan arunsrinivasan added the High label Jun 10, 2014

@arunsrinivasan arunsrinivasan added this to the v1.9.4 milestone Jun 19, 2014

@arunsrinivasan arunsrinivasan self-assigned this Jun 25, 2014

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arunsrinivasan Jun 26, 2014

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update: fixed in commit 1311, 5e2ced0. All good!

Just realised that this only fixes this case, but not DT[, z := list(list(y)), by=x]. Will reopen and fix soon.

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arunsrinivasan commented Jun 26, 2014

update: fixed in commit 1311, 5e2ced0. All good!

Just realised that this only fixes this case, but not DT[, z := list(list(y)), by=x]. Will reopen and fix soon.

mattdowle added a commit that referenced this issue Oct 18, 2016

Removed 58 lines of complex and duplicated lines from dogroups.c deal…
…ing with .BY and list columns. Removed switch on R 3.1.0. Added simpler code to central memrecycle. Turned back on test 1691. All tests now pass R 3.0.0 (pre R 3.1.0) and R 3.3.1. Closes #1270. Simplifies #481.
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