diff(tmp[idx]) cheers,
b On Nov 13, 2006, at 3:06 PM, Leeds, Mark ((IED)) wrote: > I have the following set of indices, call it idx, that correspond > to the > indices of a vector say temp. > > [1] 31 36 41 61 66 71 91 96 101 121 126 131 151 > 156 161 181 186 191 211 216 221 241 246 251 271 276 281 > 301 306 311 331 336 341 361 366 > [36] 371 391 396 401 421 426 431 451 456 461 481 486 491 > 511 516 521 541 546 551 571 576 581 601 606 611 631 636 > 641 661 666 671 691 696 701 721 > [71] 726 731 751 756 761 781 786 791 811 816 821 841 846 > 851 871 876 881 901 906 911 931 936 941 961 966 971 991 > 996 1001 1021 1026 1031 1051 1056 1061 > [106] 1081 1086 1091 1111 1116 1121 1141 1146 1151 1171 1176 1181 1201 > 1206 1211 1231 1236 1241 1261 1266 1271 1291 1296 1301 1321 1326 1331 > 1351 1356 1361 1381 1386 1391 1411 1416 > [141] 1421 > > > I want to calculate temp[36] - temp[31] and temp[41] - temp[36] > > Similarly, temp[66] - temp[61] and temp[71] - temp[66] > . > . > . > . > Similarly temp[1416]-temp[1411] > temp[1421] - temp[1416] > > > I'm doing this because the above subractions represent pairs of > returns > and the correlations between them wil be calculated eventually. > > In other words, eventually I will have > > X_36_31 ( i.e : temp[36] - temp[31] ) > X_66-61 > X_96-91 > . > . > . > . > . > . > . > X_1411-1416 > > as one vector and > > Y_41-36 > Y_71-66 > Y_101-96 > . > . > . > . > . > Y_1416_1421 > > as another vector. > > and will calculate the correlation between the two vectors in order to > get one number. > > > The point is I am really only using the indices 31, 61, 91 etc as > anchor's so a regular diff(temp[idx]) won't work because it will diff > all > the elements that are next to each other ? This is a weird problem. > I'm > still thinking about it. I'm hoping to figure it out before someone > sends me something but I won't mind so much if I get an external > solution first. I have no pride. > -------------------------------------------------------- > > This is not an offer (or solicitation of an offer) to buy/se... > {{dropped}} > > ______________________________________________ > R-help@stat.math.ethz.ch 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. ______________________________________________ R-help@stat.math.ethz.ch 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.