Hi, Not exactly sure what you mean, but try
? intersect and see if this matches your need. Cheers, Umesh On Sun, Mar 29, 2009 at 6:28 PM, Gabor Grothendieck <ggrothendi...@gmail.com > wrote: > Example 7c has been aded to the home page which illustrates how > to do this using nested selects. > http://sqldf.googlecode.com > > 2009/3/29 Schragi Schwartz <schra...@post.tau.ac.il>: > > Hi, > > Again, thank you for your extremely helpful answer. I'll try my luck a > third > > time with a similar but different question: assuming I have two > dataframes, > > a and b, each of which containing a set of start and end coordinates, and > I > > want to create a new dataframe c, which contains all coordinates in a > which > > are are overlapped by any coordinate in b. Can I do this via sqldf()? Or > is > > there any other way to do this? > > > > Thank you very much! > > Schragi > > > > -----Original Message----- > > From: Gabor Grothendieck [mailto:ggrothendi...@gmail.com] > > Sent: Wednesday, March 25, 2009 3:44 PM > > To: Schragi Schwartz > > Cc: r-help@r-project.org > > Subject: Re: [R] Merging rows in dataframes > > > > I've added an example to FAQ 3 on the home page that > > illustrates group_concat. > > http://sqldf.googlecode.com > > > > On Wed, Mar 25, 2009 at 9:06 AM, Gabor Grothendieck > > <ggrothendi...@gmail.com> wrote: > >> In the Links box to the right on the sqldf home page click on > >> "SQLite - aggregate functions" and lookup group_concat. > >> > >> On Wed, Mar 25, 2009 at 9:05 AM, Schragi Schwartz > >> <schra...@post.tau.ac.il> wrote: > >>> Thank you, your answer was extremely helpful. One last problem though: > > one > >>> of the aggregate functions I'd like to apply on the columns is > >>> concatentation (equivalent to the paste() function). So if I have a > given > >>> character column in three separate rows sharing the same ids with the > > value > >>> "apple" in the first, "banana" in the second, and "orange" in the > third, > > in > >>> the summarizing row I'd like to receive output in the form > >>> "apple|banana|orange". Is there any way to do this? > >>> > >>> Thanks again, > >>> Schragi > >>> > >>> -----Original Message----- > >>> From: Gabor Grothendieck [mailto:ggrothendi...@gmail.com] > >>> Sent: Tuesday, March 24, 2009 12:50 AM > >>> To: Schraga Schwartz > >>> Cc: r-help@r-project.org > >>> Subject: Re: [R] Merging rows in dataframes > >>> > >>> Using sqldf you only need two statements, infile <- file(...) and > >>> DF <- sqldf("select min(a), max(b), mean(c), ... from infile group by > > id"). > >>> The file statement identifies the filename and the second reads it > >>> into sqlite (without > >>> going through R), summarizes it and then reads the summarized version > >>> into R. You may also need to provide info on its format if its not in > > the > >>> default format. See example 4a on home page and the other examples > >>> there: > >>> http://sqldf.googlecode.com > >>> > >>> > >>> On Mon, Mar 23, 2009 at 5:58 PM, Schraga Schwartz > >>> <schra...@post.tau.ac.il> wrote: > >>>> Hello, > >>>> > >>>> I have a dataframe with 40 columns and around 450,000 rows. The first > >>> column > >>>> in each row is a factor id and the remaining are numeric. Some rows > have > >>> the > >>>> same ids. What I want to do is to merge each set of rows sharing the > > same > >>>> ids (id set) into one single row (summarizing row) with that id. To > > create > >>>> the summarizing row, I'd like to apply a different function on each of > > the > >>>> original columns in the id set. Some columns within the summarizing > row > >>> will > >>>> equal the mean of the columns in the id set, others will equal the > >>> minimum, > >>>> others the maximum. > >>>> > >>>> To do this, I tried using the by() function. However, this was > extremely > >>>> slow (it ran for more than two hours before I stopped it). Also, it > used > >>> up > >>>> all of 16 GB of memory on my machine. Is there any more efficient > >>> function, > >>>> both in terms of time and memory, to do this sort of thing? > >>>> > >>>> Thank you very much, > >>>> Schraga Schwartz > >>>> > >>>> ______________________________________________ > >>>> R-help@r-project.org mailing list > >>>> https://stat.ethz.ch/mailman/listinfo/r-help > >>>> PLEASE do read the posting guide > >>> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html> > >>>> and provide commented, minimal, self-contained, reproducible code. > >>>> > >>> > >>> > >> > > > > > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html> > and provide commented, minimal, self-contained, reproducible code. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org 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.
