Hi > -----Original Message----- > From: [email protected] [mailto:r-help-bounces@r- > project.org] On Behalf Of Stodola, Kirk > Sent: Thursday, November 29, 2012 5:32 PM > To: [email protected] > Subject: [R] Deleting certain observations (and their imprint?) > > I'm manipulating a large dataset and need to eliminate some > observations based on specific identifiers. This isn't a problem in > and of itself (using which.. or subset..) but an imprint of the deleted > observations seem to remain, even though they have 0 observations. > This is causing me problems later on. I'll use the dataset warpbreaks > to illustrate, I apologize if this isn't in the best format > > ##Summary of warpbreaks suggests three tension levels (H, M, L) > > summary(warpbreaks) > > breaks wool tension > Min. :10.00 A:27 L:18 > 1st Qu.:18.25 B:27 M:18 > Median :26.00 H:18 > Mean :28.15 > 3rd Qu.:34.00 > Max. :70.00 > > ## Subset the dataset and keep only those observations with "L" > > wb.subset <- warpbreaks[which(warpbreaks$tension=="L"),]
wb.subset <- warpbreaks[which(warpbreaks$tension=="L"), , drop=TRUE] or warpbreaks$tension <- factor(warpbreaks$tension) or change tension from factor to character vector. Regards Petr > > > ##Summary of the subsetted data shows: L=18, M=0, H=0, Why is M and H > still included? > > summary(wb.subset) > > breaks wool tension > Min. :14.00 A:9 L:18 > 1st Qu.:26.00 B:9 M: 0 > Median :29.50 H: 0 > Mean :36.39 > 3rd Qu.:49.25 > Max. :70.00 > > ##The subsetted dataset does not show M or H > > wb.subset > > Is there a way that M & H can be completely eliminated (i.e. they don't > show up in summary)? The only way I found was to export the dataset and > then reimport, which seems pretty cumbersome. Thanks in advance for > any help. -Kirk > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting- > guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
