Alexy Khrabrov wrote: > What are idioms for taking a head or a tail of a vector, either up to > an index, or from an index to the end? Also -- is it necessary to > use length(v) to refer to the last element? E.g., Python has > > v[:3] # indices 0,1,2 > v[3:] # indices 3,4,... > v[-1] # the last element of v > v[:-1] # all but last
?head For example: > x <- runif(10) > x [1] 0.60253459 0.51895186 0.01080359 0.68675829 [5] 0.58588120 0.41019752 0.25345482 0.84928989 [9] 0.78826981 0.01696331 > head(x, 3) [1] 0.60253459 0.51895186 0.01080359 > tail(x, -3) [1] 0.68675829 0.58588120 0.41019752 0.25345482 [5] 0.84928989 0.78826981 0.01696331 > tail(x, 1) [1] 0.01696331 > head(x, -1) [1] 0.60253459 0.51895186 0.01080359 0.68675829 [5] 0.58588120 0.41019752 0.25345482 0.84928989 [9] 0.78826981 > Cheers, > Alexy > > ______________________________________________ > 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. -- Chuck Cleland, Ph.D. NDRI, Inc. 71 West 23rd Street, 8th floor New York, NY 10010 tel: (212) 845-4495 (Tu, Th) tel: (732) 512-0171 (M, W, F) fax: (917) 438-0894 ______________________________________________ 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.