<html><head><style>body{font-family:Helvetica,Arial;font-size:13px}</style></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;">This is now fixed with commit #1256 from v1.9.3. Thanks Christophe for filing #5437 and Paul for following up. I'll close it now. Please write back if you find something's not right still.</div><div id="bloop_customfont" style="font-family:Helvetica,Arial;font-size:13px; color: rgba(0,0,0,1.0); margin: 0px; line-height: auto;"><br></div> <div id="bloop_sign_1396777502493922048" class="bloop_sign"><div style="font-family:helvetica,arial;font-size:13px">Arun</div></div> <div style="color:black"><br>From: <span style="color:black">Paul Johnson</span> <a href="mailto:pauljohn32@gmail.com">pauljohn32@gmail.com</a><br>Reply: <span style="color:black">Paul Johnson</span> <a href="mailto:pauljohn32@gmail.com">pauljohn32@gmail.com</a><br>Date: <span style="color:black">March 31, 2014 at 2:03:48 AM</span><br>To: <span style="color:black">DERVIEUX Christophe</span> <a href="mailto:christophe.dervieux@rte-france.com">christophe.dervieux@rte-france.com</a><br>Cc: <span style="color:black">datatable-help@lists.r-forge.r-project.org</span> <a href="mailto:datatable-help@lists.r-forge.r-project.org">datatable-help@lists.r-forge.r-project.org</a><br>Subject: <span style="color:black"> Re: [datatable-help] In 1.9.2, By with factor column do not work the same as in 1.8.10 <br></span></div><br> <blockquote type="cite" class="clean_bq"><span><div><div></div><div>
<title></title>
<div dir="ltr">
<div>
<div>
<div>Hi<br>
I see this problem too. I was not using data.table before 1.9, so I
did no realize it ever behaved differently. In the examples
I've tried, any calculation that I expect to create a factor seems
to create an integer that uses the R internal integer of the
factor. <br>
<br>
I noticed this, I thought maybe I needed to do more explicit
casting to make it come out as a factor. Here's my variable to lag
a factor that beats the point into the ground.<br>
<br>
lagFactor <- function(x, N){<br>
xold <- x<br>
if (is.factor(x)) {<br>
xlev <-
levels(x)<br>
xnum <-
as.numeric(x)<br>
} else {<br>
xlev <-
unique(x)<br>
}<br>
xlag <- c(rep(NA, N),
xnum[-(length(xnum):(length(xnum)-N+1))])<br>
xlagf <- factor(xlev[xlag], levels =
xlev)<br>
xlagf<br>
}<br>
<br></div>
<div>dat is a data.table with lots of lines, I can give you a copy
if you want.<br>
<br></div>
<div>Now I'll show you that the result is different in and out of a
data.table.<br></div>
<div><br>
> xx <- lagFactor(dat$east2b, 1)<br></div>
</div>
> table(xx)<br>
xx<br>
Yes No<br>
130232 151885<br>
> levels(xx)<br>
[1] "Yes" "No"<br>
> dat[ , xx := lagFactor(east2b, 1), by = c("sippid"),
roll = TRUE]<br>
> table(dat$xx)<br>
<br>
1 2<br>
114963 130095<br>
> levels(dat$xx)<br>
NULL<br>
> table(xx, dat$xx)<br>
<br>
xx
1 2<br>
Yes 114963 0<br>
No 0 130095<br>
<br>
<br></div>
<div>For my case, the only fix is an explicit
re-factoring. <br></div>
<div><br></div>
<div> pj<br></div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Fri, Mar 28, 2014 at 5:29 AM, DERVIEUX
Christophe <span dir="ltr"><<a href="mailto:christophe.dervieux@rte-france.com" target="_blank">christophe.dervieux@rte-france.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div link="blue" vlink="purple" lang="FR">
<div>
<p class="MsoNormal"><span lang="EN-US">Hi,<br>
<br>
I have updated data.table package to 1.9.2 recently from 1.8.10 and
I found errors on my previous code.<br>
<br>
See reproductible example below:<br>
<br>
On 1.8.10 :<br>
DT<-data.table(X=factor(2006:2012),Y=rep(1:7,2))<br>
DT[,Z:=paste(X,.N,sep=" - "),by=list(X)][]<br>
<br>
X Y Z<br>
1: 2006 1 2006 - 2<br>
2: 2007 2 2007 - 2<br>
3: 2008 3 2008 - 2<br>
4: 2009 4 2009 - 2<br>
5: 2010 5 2010 - 2<br>
6: 2011 6 2011 - 2<br>
7: <a href="tel:2012%207%202012%20-%202" value="+12012720122" target="_blank">2012 7 2012 - 2</a><br>
8: 2006 1 2006 - 2<br>
9: 2007 2 2007 - 2<br>
10: 2008 3 2008 - 2<br>
11: 2009 4 2009 - 2<br>
12: 2010 5 2010 - 2<br>
13: 2011 6 2011 - 2<br>
14: <a href="tel:2012%207%202012%20-%202" value="+12012720122" target="_blank">2012 7 2012 - 2</a><br>
<br>
In column Z, I get the level of the factor column X<br>
pasted with count '.N' as expected<br>
<br>
However, in the 1.9.2, with same code :<br>
DT<-data.table(X=factor(2006:2012),Y=rep(1:7,2))<br>
DT[,Z:=paste(X,.N,sep=" - "),by=list(X)][]<br>
<br>
X Y Z<br>
1: 2006 1 1 - 2<br>
2: 2007 2 2 - 2<br>
3: 2008 3 3 - 2<br>
4: 2009 4 4 - 2<br>
5: 2010 5 5 - 2<br>
6: 2011 6 6 - 2<br>
7: 2012 7 7 - 2<br>
8: 2006 1 1 - 2<br>
9: 2007 2 2 - 2<br>
10: 2008 3 3 - 2<br>
11: 2009 4 4 - 2<br>
12: 2010 5 5 - 2<br>
13: 2011 6 6 - 2<br>
14: 2012 7 7 - 2<br>
<br>
as results, I do not get levels of factor column X but the numeric
values associated with the level.<br>
<br>
is this working normally? Why has it changed? Is that a bug?<br>
<br>
I use this kind of procedure to make labels for ggplot. All my
previous code is not working anymore. It's kind of annoying.<br>
<br></span>Thanks<span class="HOEnZb"><font color="#888888"><br>
<br>
Christophe</font></span></p>
<p class="MsoNormal"> </p>
</div>
</div>
<br>
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</blockquote>
</div>
<br>
<br clear="all">
<br>
--<br>
Paul E. Johnson<br>
Professor, Political Science Assoc.
Director<br>
1541 Lilac Lane, Room 504 Center for Research
Methods<br>
University of Kansas
University of Kansas<br>
<a href="http://pj.freefaculty.org" target="_blank">http://pj.freefaculty.org</a>
<a href="http://quant.ku.edu" target="_blank">http://quant.ku.edu</a></div>
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