Your question is impossible to parse "I would like sort of " ... sort of what?
vlookup is an Excel function that returns the value in one column based on a value in another column; by default it finds the index of the largest value in the first column of the table less than the target, and returns the corresponding element of the specified column (default is the second column) If you want to look up cdf values and return seq or rand values, then it depends on how they're stored (e.g. separate vectors vs a matrix or a data frame). You should post some pasteable code that illustrates what you want. My initial example works if they're stored as separate vectors (I read into a data frame but attach()'ed it so I could refer to the columns as if they were individual vectores, while my following function works on data frames. There are other ways to do it. mytable <- read.table(stdin(),header=TRUE) cdf seq rand 0.00E+00 0 0.2621 1.56E-03 20 0.9643 1.55E-02 40 0.4948 5.30E-02 60 0.7337 1.16E-01 80 0.8004 1.97E-01 100 0.9257 2.88E-01 120 0.0476 3.80E-01 140 0.2661 4.68E-01 160 0.1255 5.48E-01 180 0.7012 6.18E-01 200 0.9158 6.79E-01 220 0.7360 7.32E-01 240 0.5178 7.76E-01 260 0.0421 8.13E-01 280 0.5683 8.44E-01 300 0.0671 8.70E-01 320 0.7144 8.92E-01 340 0.7122 9.10E-01 360 0.2885 9.26E-01 380 0.1859 9.38E-01 400 0.1089 9.49E-01 420 0.5134 9.57E-01 440 0.2221 9.65E-01 460 0.5004 9.71E-01 480 0.4378 9.76E-01 500 0.8518 9.80E-01 520 0.8035 9.83E-01 540 0.2498 9.86E-01 560 0.8592 9.88E-01 580 0.1269 9.90E-01 600 0.7134 attach(mytable) > max(which(cdf<=0.5)) [1] 9 > seq[max(which(cdf<=0.5))] [1] 160 > rand[max(which(cdf<=0.3))] [1] 0.0476 In fact, we can readily define a function which probably does most of what you want: lookv <- function(x,ltab,rcol=2) ltab[max(which(ltab[,1]<=x)),rcol] > lookv(0.5,mytable) [1] 160 > lookv(0.3,mytable,3) [1] 0.0476 Hope that helps On Fri, May 28, 2010 at 11:13 AM, Roslina Zakaria <zrosl...@yahoo.com> wrote: > Hi r users, > > I would like sort of > > cdf seq rand > 0.00E+00 0 0.262123478 > 1.56E-03 20 0.964293344 > 1.55E-02 40 0.494827113 > 5.30E-02 60 0.733726005 > 1.16E-01 80 0.800408948 > 1.97E-01 100 0.925748466 > 2.88E-01 120 0.047578356 > 3.80E-01 140 0.266060366 > 4.68E-01 160 0.125522629 > 5.48E-01 180 0.701193274 > 6.18E-01 200 0.915799432 > 6.79E-01 220 0.735984375 > 7.32E-01 240 0.517838069 > 7.76E-01 260 0.042085025 > 8.13E-01 280 0.568346202 > 8.44E-01 300 0.067140721 > 8.70E-01 320 0.71437727 > 8.92E-01 340 0.712210456 > 9.10E-01 360 0.288460952 > 9.26E-01 380 0.185857723 > 9.38E-01 400 0.108859523 > 9.49E-01 420 0.513351848 > 9.57E-01 440 0.22214423 > 9.65E-01 460 0.500350963 > 9.71E-01 480 0.437818537 > 9.76E-01 500 0.851771599 > 9.80E-01 520 0.803521836 > 9.83E-01 540 0.249824519 > 9.86E-01 560 0.859248634 > 9.88E-01 580 0.126926481 > 9.90E-01 600 0.713431196 > 0.253425703 > 0.830195013 > 0.723929563 > 0.027588733 > 0.091067232 > 0.689504685 > 0.890469069 > 0.710440382 > > > > > > > [[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. > > ______________________________________________ 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.