similar to: General binary search?

Dear R users, the help for findInterval(x,vec) suggests a logarithmic dependence on N (=length(vec)), which would imply a binary search type algorithm. However, when I "test" this hypothesis, in the following manner: set.seed(-3645); l <- vector(); N.seq <- c(5000, 500000, 1000000, 10000000, 50000000);k <- 1 for (N in N.seq){ tmp <- sort(round(stats::rt(N, df=2), 2));

Dear R Community, I hope you might be able to assist with a small problem creating a function. I am working with water-quality data sets that contain the concentration of many different elements in water samples. I need to assign quality-control flags to values that fall into various concentration ranges. Rather than a web of nested if statements, I am employing the findInterval function to

What should findInterval(x,vec,all.inside=TRUE) return when length(vec)<=1, so there are no inside intervals? R-3.3.0 gives a decreasing map of x->output when length(vec)==1 and -1's when length(vec)==0. Would '0' in all those cases be better? > findInterval(x=c(10, 11, 12), vec=11, all.inside=TRUE, rightmost.closed=FALSE, left.open=FALSE) [1] 1 0 0 >

Suppose we have `dat` shown below and we want to find the the `y` value corresponding to the last value in `x` equal to the corresponding component of `seek` and we wish to return an output the same length as `seek` using `findInterval` to perform the search. This returns the correct result: dat <- data.frame(x = c(2, 2, 3, 4, 4, 4), y = c(37, 12, 19, 30, 6, 15), seek = 1:6)

>>>>> Gabor Grothendieck >>>>> on Mon, 16 Sep 2024 11:21:55 -0400 writes: > Suppose we have `dat` shown below and we want to find the the `y` value > corresponding to the last value in `x` equal to the corresponding component > of `seek` and we wish to return an output the same length as `seek` using > `findInterval` to perform the

Hello Wise Ones... I need a clever way around a problem with findInterval. Consider: vec1 <- 1:10 vec2 <- seq(1, 10, by = 0.1) x1 <- c(2:3) a1 <- findInterval(x1, vec1); a1 # example 1 a2 <- findInterval(x1, vec2); a2 # example 2 In the problem I'm working on, vec* may be either integer or numeric, like vec1 and vec2. I need to remove one or more sections of this vector;

> On Apr 19, 2018, at 1:22 PM, David Winsemius <dwinsemius at comcast.net> wrote: > > >> On Apr 19, 2018, at 11:20 AM, Ding, Yuan Chun <ycding at coh.org> wrote: >> >> Hi All, >> >> I want to create a categorical variable, cat.pfoa, in the file of pfas.pheno (a data frame) based on log2pfoa values. I can do it using the following code.

> On Apr 19, 2018, at 11:20 AM, Ding, Yuan Chun <ycding at coh.org> wrote: > > Hi All, > > I want to create a categorical variable, cat.pfoa, in the file of pfas.pheno (a data frame) based on log2pfoa values. I can do it using the following code. > > pfas.pheno <-within(pfas.pheno, {cat.pfoa<-NA > cat.pfoa[pfas.pheno$log2pfoa

I've found over time that R documentation that comes off as terse at first blush is usually revealed to be precise, concise, and complete on close reading.? I'm sure this is also true of `?findInterval`, but for whatever reason my brain simply refuses to extract meaning from it. Part of the problem may be that we interact with the function via a compressed form of the bounds of the

I am attempting to emulate the VLOOKUP function from Excel in R. I want to compare one column (coll.minus.release) with another (release.days) to get the number of parasitoid released at that time (TotalParasitoids). for example: coll.minus.release release.days ParasitoidTotal -12 -266 1700 8 -259 1000 8

On Thu, Apr 14, 2011 at 7:02 PM, <rcpp-devel-request at r-forge.wu-wien.ac.at> wrote: > I was able to write a very short C++ function using the Rcpp package > that provided about a 1000-fold increase in speed relative to the best > I could do in R. ?I don't have the script on this computer so I will > post it tomorrow when I am back on the computer at the office. > >

Hi all, I am writing some C code where I want to use the findInterval function documented in "Writing R extensions/Utility functions". i.e. the C-version not the R version. It all compiles but the shared library is causing seg-faults and I'm obviously stuffing something up. Has anyone got any examples of calling this function they'd be will to share? I've searched through

Dear all, I would like to produce a map with information about the patenting activity in German districts, by coloring districts with different degrees of patenting activity in different colors. I work with the packages maptools, maps and spdep. The map data is read from an external .shp file (+ the corresponding .shx and .dbf files). Plotting a map with the IDs or the patenting indicator itself

This must be FAQ, but I can't find it in archives or with a site search. I am trying to construct a frequency table. I guess this should be done with table. Or perhaps factor and split. Or prop.table. cut? findInterval? Argh! Please correct me if what I am looking for is not called a "frequency table". Perhaps it's called grouped data. > zz$x9 [1] 65 70 85 65 65 65 62 55

Dear R users, i try to calculate the probabilty to survive a given time by using the estimated survival curve by kaplan meier. What is the right way to do that? as far as is see i cannot use the predict-methods from the survival package? library(survival) set.seed(1) time <- cumsum(rexp(1000)/10) status <- rbinom(1000, 1, 0.5) ## kaplan meier estimates fit <- survfit(Surv(time,

Hi, I have a matrix of X and Y coordinates, and one pair of coordinates that I need to know it corresponds (or is closest) to which row in the matrix. For example: MC<- cbind(rep(1:1000,each=1000),rep(1:1000,1000)); p<-c(543.1,440.05); I know that if you do which.min you'll get the answer, which will be row # 542440, but which.min is slow and this process needs to be repeated a lot. I

Dear R users, I want to group the d values in classes. If I use this script I have a problem. classes <- function(x, n){ s <- seq(0, ceiling(max(x)), by = n) factor(n*findInterval(x, s), levels = s) } z<-sapply(tapply(t$d,t$plot,function(x) classes(t$d, 4)),table) z<-cbind(z) Thank you! Initial data: nr x y d plot plotn xplot yplot 121 162 50.26989 46.230

I have two vectors, a and b. b is a text file. I want to find in b those elements of a which occur at the beginning of the line in b. I have the following code, but it only returns a value for the first value in a, but I want both. Any ideas please. a = c(2,3) b = NULL b[1] = "aaa 2 aaa" b[2] = "2 aaa" b[3] = "3 aaa" b[4] = "aaa 3 aaa"

If one makes the reasonable assumption that Pct is much larger than Cutoff, sorting Cutoff is the expensive part e.g O(nlog2(n) for Quicksort (n = length Cutoff). I believe looping is O(n^2). Jeff's approach using findInterval may be faster. Of course implementation details matter. -- Bert On Mon, Oct 16, 2023 at 4:41?AM Leonard Mada <leo.mada at syonic.eu> wrote: > > Dear

input: > values [1] 0.854400 1.648465 1.829830 1.874704 7.670915 7.673585 7.722619 > thresholds [1] 1 3 5 7 9 expected output: [1] 1 4 4 4 7 That is, need a vector of indexes of the maximum value below the threshold. e.g. First element is "1", because value[1] is the largest below threshold "1". Second element is "4", because value[4] is the