<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 14 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
@font-face
{font-family:Tahoma;
panose-1:2 11 6 4 3 5 4 4 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri","sans-serif";}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>not sure but try data.table::rbindlist like this (it should be faster too)<o:p></o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>rbindlist(lapply(c("~/tmp/new.csv", "~/tmp/new2.csv"), function(x) as.data.table(read.csv(x)))<o:p></o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>~Malcolm<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div style='border:none;border-left:solid blue 1.5pt;padding:0in 0in 0in 4.0pt'><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> datatable-help-bounces@lists.r-forge.r-project.org [mailto:datatable-help-bounces@lists.r-forge.r-project.org] <b>On Behalf Of </b>G See<br><b>Sent:</b> Wednesday, November 07, 2012 3:53 PM<br><b>To:</b> datatable-help@lists.r-forge.r-project.org<br><b>Subject:</b> [datatable-help] rbinding an empty data.table and a non-empty data.table<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><div><p class=MsoNormal>When I try to rbind an empty data.table to a non-empty data table, all my data are converted to logical. Here's an example<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal># create a directory and put 2 csv file in it.<o:p></o:p></p></div><div><p class=MsoNormal>dir.create("~/tmp")<o:p></o:p></p></div><div><p class=MsoNormal>system("echo 'A,B' > ~/tmp/new.csv") # this csv only has headers; no data<o:p></o:p></p></div><div><p class=MsoNormal>write.csv(data.frame(A=1, B=2), row.names=FALSE, file='~/tmp/new2.csv') # this one has header and 1 row<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>lapply(c("~/tmp/new.csv", "~/tmp/new2.csv"), read.csv)<o:p></o:p></p></div><div><p class=MsoNormal>#[[1]]<o:p></o:p></p></div><div><p class=MsoNormal>#[1] A B<o:p></o:p></p></div><div><p class=MsoNormal>#<0 rows> (or 0-length row.names)<o:p></o:p></p></div><div><p class=MsoNormal>#<o:p></o:p></p></div><div><p class=MsoNormal>#[[2]]<o:p></o:p></p></div><div><p class=MsoNormal># A B<o:p></o:p></p></div><div><p class=MsoNormal>#1 1 2<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal># now rbind them, and we're left with the data from the non-empy csv<o:p></o:p></p></div><div><p class=MsoNormal>do.call(rbind, lapply(c("~/tmp/new.csv", "~/tmp/new2.csv"), read.csv))<o:p></o:p></p></div><div><p class=MsoNormal># A B<o:p></o:p></p></div><div><p class=MsoNormal>#1 1 2<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal># Now let's try to work with data.tables instead of data.frames<o:p></o:p></p></div><div><p class=MsoNormal>lapply(c("~/tmp/new.csv", "~/tmp/new2.csv"), function(x) as.data.table(read.csv(x)))<o:p></o:p></p></div><div><p class=MsoNormal>#[[1]]<o:p></o:p></p></div><div><p class=MsoNormal>#Empty data.table (0 rows) of 2 cols: A,B<o:p></o:p></p></div><div><p class=MsoNormal>#<o:p></o:p></p></div><div><p class=MsoNormal>#[[2]]<o:p></o:p></p></div><div><p class=MsoNormal># A B<o:p></o:p></p></div><div><p class=MsoNormal>#1: 1 2<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>#Ok, but look at what happens when we rbind them<o:p></o:p></p></div><div><p class=MsoNormal>do.call(rbind, lapply(c("~/tmp/new.csv", "~/tmp/new2.csv"), function(x) as.data.table(read.csv(x))))<o:p></o:p></p></div><div><p class=MsoNormal> A B<o:p></o:p></p></div><div><p class=MsoNormal>1: TRUE TRUE<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal> What's going on here?<o:p></o:p></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><div><p class=MsoNormal>Thanks,<o:p></o:p></p></div><div><p class=MsoNormal>Garrett<o:p></o:p></p></div></div></div></body></html>