similar to: question on graphs and finding area under a curve

I have two variables. A <- rep(c(1:9), 2) B <- rep(c(2:10),2) -- Renuka Sane http://www.nyx.net/~rsane [[alternative HTML version deleted]]

Hi all, I would like to calculate the area under the ROC curve for my predictive model. I have managed to plot points giving me the ROC curve. However, I do not know how to get the value of the area under. Does anybody know of a function that would give the result I want using an array of specificity and an array of sensitivity as input? Thanks, Olivier -- View this message in context:

I am doing a simulation with a relatively large data set (20,000 observations) for which I want to calculate the area under the Receiver Operator Curve (AUC) for many parameter combinations. I am using the ROC library and the following commands to generate each AUC: rocobj=rocdemo.sca(truth = ymis, data = model$fitted.values, rule = dxrule.sca) #generation of observed ROC object

I might be missing something but I thought that AUC was a measure for comparing ROC curves, so there is nothing else needed to "compare" them. The larger AUC is the higher correlation of 2 variables compared. No other measures or calculations are needed. Jarek Tuszynski -----Original Message----- From: r-help-bounces at stat.math.ethz.ch [mailto:r-help-bounces at stat.math.ethz.ch] On

Hello, I have a classification tree. I want to obtain a ROC curve for this test. What is the easiest way to obtain one? -Anjali --------------------------------- [[alternative HTML version deleted]]

I have two dataframes C and C1. Each has three columns viz. state, psu and weight. The dataframes are of unequal size i.e. C1 could be 2/25/50 rows and C has 42000 rows. C1 is the master table i.e. C1$state, C1$psu and C1$weight are never the same. ThisA. P., Urban, 0 is not so for C. For example C state, psu,weight A. P., Urban, 0 Mah., Rural, 0 W.B., Rural,0 Ass., Rural,0 M. P., Urban,0 A. P.,

Hello, I have this code to plot a certain normal distribution and represent the pnorm value for a certain "x": x<-300 xx <- seq(2.5,7.5, by=0.1) yy <- dnorm(xx,5.01,0.77) d<-signif(pnorm(log(x), 5.01,0.77),4) xpts <- round(exp(0:8)) par(bg = "antiquewhite") plot(xx,yy, type="l", col="blue", lwd=2, xaxt="n",

I am trying to do a forecasting exercise for a series, x. My forecast model consists of the following I first regress log(x) on time and dummy variables for each month. lm(log(x) ~ time + monthly dummies) I then use predict() to obtain a prediction for the next year. I then fit an AR(6)/AR(12) model on the residuals of the regression. I use predict() here also to obtain the prediction for the

For a given random variable rv, for instance, rv = rnorm(1000), I plot its density curve and calculate some quantiles: plot(density(rv)) P10P50P90 = = quantile(rv,probs = c(10,50,90)/100) I would like to color the area between P10 and P90 and under the curve and mark the P50 on the curve. > rv = rnorm(1000) > plot(density(rv)) > P10P50P90 = = quantile(rv,probs = c(10,50,90)/100) Could

say, I am plotting x=seq(0,5,len=100) y=-(x-5)^2 plot(x,y) how can I put some color or verticle lines below the plotted curve? [[alternative HTML version deleted]]

Hi, I want to know the area under a curve, which is not given as a function, but as values in a time series. It is not a smooth curve, but switches often between positive values and zero (the values describe the moisture in the soil over a year, one entry is one day). I already tried area.between.curves, but got only 0 as result. I guess, it doesn't work because of these multiple changes

Dear R Users, I've never used R before and my professor has asked us to do some pretty intense programming (or it's intense to me at least). Here is the question: Modify the function myquadrature inside the script so that it returns the quadrature of descrete data using the trapezoidal rule. Modify the call to the function at the bottom of the script so that is uses your modifies

Dear R users, I have spectral data (say, wavelength vs. extinction coefficient) for which I??d like to calculate an integral (i.e. the area underneath the curve). Suppose the (artificial) dataset is lambda E 1 2 2 4 3 5 4 8 5 1 6 5 7 4 8 9 9 8 10 2 How can I calculate an integral for these values using R? Many thanks for any help! Regards Christoph

Dear all, I want to measure the goodness of prediction of my linear model. That's why I was thinking about the area under roc curve. I'm trying the following, but I don't know how to avoid the error. Any help would be appreciated. library(ROCR) model.lm <- lm(log(outcome)~log(v1)+log(v2)+factor1) pred<-predict(model.lm) pred<-prediction(as.numeric(pred),

Hello! I am using function "curve" to create a line graph. I was wondering, if it's possible to "turn off" the default tick marks and introduce those tick marks in specific locations. For example, currently in my X axis tick marks are (automatically) at 10, 11, 12, 13 but I want them to be in 5 specific locations, like 9.89, 10.34, etc. Any hint would be greatly

I would like to integrate the area under a curve without any smoothing or the like- just on the raw numbers. I looked at integrate() but it requires a function which I assume means something like x+x^2+x^3 is there a built in function in R for this? #let's say x <- seq(1:50) y <- seq(1:50) plot(y~x) # the are would be 1250 # I would like to be able to do this but on more complicated

Hi List, I would like to plot multiple curves (parametric density curves) in one plot. For example: # parameters for three normal density curves parms = data.frame(ID=c(1,2,3),mu=c(50,55,60),sigma=c(10,12,15)) # I can easily draw three normal density curves using curve(): curve(dnorm(x,mean=parms$mu[1],sd=parms$sigma[1]),from=0, to=150, ylab="density", col="red")

I want to shade the area under the curve of the standard normal density. Specifically color to the left of -2 and on. How might i go about doing this? Thanks -- View this message in context: http://n4.nabble.com/Shade-area-under-curve-tp1586439p1586439.html Sent from the R help mailing list archive at Nabble.com.

Hi all, I want to provide the result from D() to curve(), because I want to plot the k-th derivative of some functions. Actually, I copy from console the result given by D() and paste inside curve(). With a lot of functions and high degree differentiation this process is tedious. Can I provide directly?? # what I actually have done (very simple function) D(expression(x^3), "x") # copy

Hi all, I've got this graphics question which really should be easy. I want to shade an area between bounds under a curve. A suitable beginning seems to be the following: > plot(dnorm,-4,4) > segments(-4,0,4,0) > segments(-2,0,-2,dnorm(-2)) > segments(2,0,2,dnorm(2)) It is the area between -2 and 2 which I want to shade (or something similar). Hints anyone? Robert