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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">I can't replicate this problem using data.table 1.8.7 (installed about 3 weeks ago) on
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<div>R version 2.15.2 (2012-10-26)</div>
<div>Platform: i386-w64-mingw32/i386 (32-bit)</div>
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<div>Michael</div>
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<div id="divRpF647456" style="direction: ltr;"><font face="Tahoma" size="2" color="#000000"><b>From:</b> datatable-help-bounces@lists.r-forge.r-project.org [datatable-help-bounces@lists.r-forge.r-project.org] on behalf of Victor Kryukov [victor.kryukov@gmail.com]<br>
<b>Sent:</b> Tuesday, 26 February 2013 9:26 AM<br>
<b>To:</b> datatable-help@lists.r-forge.r-project.org<br>
<b>Subject:</b> [datatable-help] Potential bug with sorting/summarizing by POSIXct and logical column<br>
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<div dir="ltr">Hello,
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<div>I've encounted what looks like a bug while sorting by POSIXct and logical column, which may or may not be related to the following bug:</div>
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<div><a href="https://r-forge.r-project.org/tracker/index.php?func=detail&aid=2552&group_id=240&atid=975" target="_blank">https://r-forge.r-project.org/tracker/index.php?func=detail&aid=2552&group_id=240&atid=975</a><br>
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<div>Here are all the details: <a href="http://stackoverflow.com/questions/15077232/data-table-not-summarizing-properly-by-two-columns" target="_blank">
http://stackoverflow.com/questions/15077232/data-table-not-summarizing-properly-by-two-columns</a></div>
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<div style="">Here is the test case:</div>
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<div> # First some data</div>
<div> data <- data.table(structure(list(</div>
<div> month = structure(c(1356998400, 1356998400, 1356998400, </div>
<div> 1359676800, 1354320000, 1359676800, 1359676800, 1356998400, 1356998400, </div>
<div> 1354320000, 1354320000, 1354320000, 1359676800, 1359676800, 1359676800, </div>
<div> 1356998400, 1359676800, 1359676800, 1356998400, 1359676800, 1359676800, </div>
<div> 1359676800, 1359676800, 1354320000, 1354320000), class = c("POSIXct", </div>
<div> "POSIXt"), tzone = "UTC"), </div>
<div> portal = c(TRUE, TRUE, FALSE, TRUE, </div>
<div> TRUE, TRUE, TRUE, TRUE, TRUE, FALSE, TRUE, FALSE, TRUE, FALSE, </div>
<div> TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE, TRUE</div>
<div> ), </div>
<div> satisfaction = c(10L, 10L, 10L, 9L, 10L, 10L, 9L, 10L, 10L, </div>
<div> 9L, 2L, 8L, 10L, 9L, 10L, 10L, 9L, 10L, 10L, 10L, 9L, 10L, 9L, </div>
<div> 10L, 10L)), </div>
<div> .Names = c("month", "portal", "satisfaction"), </div>
<div> row.names = c(NA, -25L), class = "data.frame"))</div>
<div> </div>
<div> # Summarizing by month, portal with tapply works:</div>
<div> </div>
<div> > tapply(data$satisfaction, list(data$month, data$portal), mean)</div>
<div> FALSE TRUE</div>
<div> 2012-12-01 8.5 8.000000</div>
<div> 2013-01-01 10.0 10.000000</div>
<div> 2013-02-01 9.0 9.545455</div>
<div> </div>
<div> # Summarizing with 'by' argument of data.table does not:</div>
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<div> > data[, mean(satisfaction), by = 'month,portal']> </div>
<div> data[, mean(satisfaction), by = list(month, portal)]</div>
<div> month portal V1</div>
<div> 1: 2013-01-01 FALSE 10.000000</div>
<div> 2: 2013-02-01 TRUE 9.000000</div>
<div> 3: 2013-01-01 TRUE 10.000000</div>
<div> 4: 2012-12-01 FALSE 8.500000</div>
<div> 5: 2012-12-01 TRUE 7.333333</div>
<div> 6: 2013-02-01 TRUE 9.666667</div>
<div> 7: 2013-02-01 FALSE 9.000000</div>
<div> 8: 2012-12-01 TRUE 10.000000</div>
<div> </div>
<div> # Summarizing only this year's data works:</div>
<div> data[month >= ymd(20130101), mean(satisfaction), by = 'month,portal']</div>
<div> month portal V1</div>
<div> 1: 2013-01-01 TRUE 10.000000</div>
<div> 2: 2013-01-01 FALSE 10.000000</div>
<div> 3: 2013-02-01 TRUE 9.545455</div>
<div> 4: 2013-02-01 FALSE 9.000000</div>
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<div>Yours Sincerely,<br>
Victor Kryukov<br>
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