search for: trapz

Dear All,   I have the following example:   a <-matrix(c(1:100),ncol=10) b <-matrix(c(2,4,6,8,10,12,14,16,18,20))   trapz(b,a)   will give me a result of 99, which it seems to me is the AUC of the 1st column only. Is it possible to get the AUC results by columns of "a" using the same "b" values in the calculations as opposed to just generating the result for the 1st column? It would be important th...

...x - Integral(f_y)dx |.) Computing this integral looks non trivial. I guess I should interpolate the points of f_y over x and integrate both lines on these intervals. Even then I would miss points where the lines cross. There are functions to integrate below *one* line (I'm thinking about the trapz function in caTools). Do you know if there is a function to do this integration properly with two lines (and especially their absolute difference)? Regards, Xavier

...* 1:3 Each cell of the rasterfinal will have the AREA UNDER CURVE formed by the values in each cell of the three original rasters. For example: s[4] has the values: 4,8,12 y<-s[4]; x<-0:2; You can see the AUC in this graph: plot(x,y, type='l') And calculate it using the function trapz (package:pracma) library(pracma) trapz(x,y) ################################################################################# My idea was to use 'stackApply': FINAL<-stackApply(s,1,myFUN) with: myFUN=function(y) { x<-1:length(y) trapz(x,y) } It doesn´t work. What I am doing wrong?...

I could do this in various hacky ways, but what's the right way? I have a nice application of the by function, which does what I want. The output looks like this: > auc_stress lab.samples.stress$subid: 2 cortisol amylase 1 919.05 6834.8 ---------------------------------------------------------------------------------------------------------------------------

...` require integer inputs now (these functions are not used in the packages below). I received a dependency report saying that *** Changes to worse in reverse dependencies *** celltrackR, geostatsp, gmvjoint, hypr, randnet Example: geostatsp suggests pracma, but uses only the function 'trapz' that has not changed for years and years. I cannot check this package, as probably other packages (from Bioconductor ?) are needed to install it. Example: gmvjoint imports pracma and uses 'grad', 'hessian', and 'nearest_spd'; these functions have not changed for years....

...y idea was to use 'stackApply': Para esto que necesitas es más sencillo usar calc. Si quieres usar stackApply, debes indicar rep(1, 3) como índices en lugar de sólo 1. Así, la función será (los ... son necesarios en stackApply): myFUN <- function(y, ...) { x <- seq_along(y) trapz(x, y) } Y aplicada con calc: FINAL <- calc(s, myFUN) o con stackApply: FINAL <- stackApply(s, rep(1, 3), myFUN) Saludos. Oscar. -- Oscar Perpiñán Lamigueiro Grupo de Sistemas Fotovoltaicos (IES-UPM) Dpto. Ingeniería Eléctrica (EUITI-UPM) URL: http://procomun.wordpress.com Twitter: @o...

Hi, I have a data frame of 2 columns with the following types : data$day char data$value num And I plot my data with : plot(strptime(donnees$day,format="%Y-%m-%d %H:%M:%S"),donnees$value, type="l") And I'd just like to get the numerical value of the integration of this graph. I looked at ?integrate but, as far as I understood (that is, not very much, due to my poor

Question on graphs: The default case for drawing a graph in R, is where a little space is left on the x and y axis before the first tick i.e. even if I say xlim=c(0,1) -- there will be some space between the edge of the x-axis and where 0 is placed. If I want 0 on the edge, how do I do it in R? Area under the curve: I have a 45 degree line and a curve above or below it. Is there a way in R

Hello, I want to know if there are some functions or packages to solve differential and integral equation using R. Thanks. Shao chunxuan. [[alternative HTML version deleted]]

...y idea was to use 'stackApply': Para esto que necesitas es más sencillo usar calc. Si quieres usar stackApply, debes indicar rep(1, 3) como índices en lugar de sólo 1. Así, la función será (los ... son necesarios en stackApply): myFUN <- function(y, ...) { x <- seq_along(y) trapz(x, y) } Y aplicada con calc: FINAL <- calc(s, myFUN) o con stackApply: FINAL <- stackApply(s, rep(1, 3), myFUN) Saludos. Oscar. -- Oscar Perpiñán Lamigueiro Grupo de Sistemas Fotovoltaicos (IES-UPM) Dpto. Ingeniería Eléctrica (EUITI-UPM) URL: http://procomun.wordpress.com Twitter: @o...