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[Request] colA:colB notation for by #1395

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franknarf1 opened this issue Oct 14, 2015 · 1 comment
Closed

[Request] colA:colB notation for by #1395

franknarf1 opened this issue Oct 14, 2015 · 1 comment
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@arunsrinivasan
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feature request
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v1.9.8

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@franknarf1
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Looking at this SO question, it seems useful:

require(data.table)
dat <- setDT(structure(list(ID = c(97330L, 118619L, 101623L, 202626L, 182925L, 
    179278L), IV1 = c(3L, 0L, 2L, 0L, 1L, 1L), DV1 = c(0L, 0L, 0L, 
    0L, 1L, 0L), DV2 = c(0L, 0L, 0L, 0L, 0L, 0L), DV3 = c(0L, 0L, 
    0L, 0L, 0L, 0L), DV4 = c(0L, 0L, 0L, 0L, 0L, 0L), DV5 = c(0L, 
    1L, 0L, 0L, 0L, 0L), DV6 = c(1L, 1L, 0L, 0L, 0L, 0L), DV7 = c(0L, 
    0L, 0L, 0L, 0L, 0L)), .Names = c("ID", "IV1", "DV1", "DV2", "DV3", 
    "DV4", "DV5", "DV6", "DV7"), class = "data.frame", row.names = c(NA, 
    -6L)))

dat[, sum(IV1), by=.(DV1, DV2, DV3, DV4, DV5, DV6, DV7)] # does work
dat[, sum(IV1), by=DV1:DV7]                              # should work

    #    DV1 DV2 DV3 DV4 DV5 DV6 DV7 V1
    #1:   0   0   0   0   0   1   0  3
    #2:   0   0   0   0   1   1   0  0
    #3:   0   0   0   0   0   0   0  3
    #4:   1   0   0   0   0   0   0  1
@DavidArenburg
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I was thinking pretty much the same when saw this question :) I think there is a related FR for this though.

@arunsrinivasan arunsrinivasan added this to the v1.9.8 milestone Oct 29, 2015
@arunsrinivasan arunsrinivasan self-assigned this Mar 4, 2016
arunsrinivasan added a commit that referenced this issue Mar 15, 2016
@arunsrinivasan
Minor fix for #1395 so that by=1:nrow(dt) works as expected.
86c96b0
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@arunsrinivasan @franknarf1 @DavidArenburg