Created
April 29, 2013 18:54
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mc_int
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mc.int<-function(mod.in,int=NULL,n=10000,int.base=0,plot=T,plot.pts=T, | |
plot.poly=T,cols=list('black','green','blue'),round.val=2,val=F){ | |
require(scales) | |
#variable names from model | |
if(is.null(mod.in$call$formula)){ | |
x.names<-colnames(eval(mod.in$call$x)) | |
y.names<-colnames(eval(mod.in$call$y)) | |
x.range<-range(eval(mod.in$call$x)) | |
} | |
else{ | |
forms<-eval(mod.in$call$formula) | |
dat.names<-model.frame(forms,data=eval(mod.in$call$data)) | |
y.names<-as.character(forms)[2] | |
x.names<-names(dat.names)[!names(dat.names) %in% y.names] | |
x.range<-range(eval(mod.in$call$data)[,x.names]) | |
} | |
#integration range if null | |
if(is.null(int)) int<-x.range | |
#create data for model fit | |
x.fit<-seq(x.range[1],x.range[2],length=n) | |
pred.dat<-data.frame(x.fit) | |
names(pred.dat)<-x.names | |
y.fit<-predict(mod.in, newdata=pred.dat) | |
dat.fit<-data.frame(x.fit,y.fit) | |
#create random integration data | |
x.rand<-runif(n,int[1],int[2]) | |
y.rand<-runif(n,int.base,max(y.fit)) | |
dat.rand<-data.frame(x.rand,y.rand,y.under=rep(cols[[1]],n),stringsAsFactors=F) | |
names(dat.rand)[1]<-x.names | |
dat.rand$y.under[y.rand<predict(mod.in,newdata=dat.rand[,1,drop=F])]<-cols[[2]] | |
y.under<-dat.rand$y.under | |
#get integration | |
area.all<-diff(range(x.rand))*diff(range(y.rand)) | |
area.und<-area.all*sum(y.under==cols[[2]])/length(y.under) | |
out.txt<-paste('Integration from',int[1],'to',int[2],'=',round(area.und,round.val), | |
sep=' ') | |
if(plot){ | |
plot(x.rand,y.rand,xlim=x.range,ylim=c(int.base,max(y.fit)),type='n',main=out.txt) | |
points(dat.fit$x.fit,dat.fit$y.fit,type='l') | |
if(plot.poly){ | |
#create data for integration polygon | |
cord.x<-seq(int[1],int[2],length=(n*diff(int)/diff(x.range))) | |
cord.x<-data.frame(cord.x) | |
names(cord.x)<-x.names | |
cord.y<-c(int.base,predict(model,newdata=cord.x),int.base) | |
cord.x<-rbind(int[1],cord.x,int[2]) | |
dat.poly<-data.frame(cord.x,cord.y) | |
names(dat.poly)[1]<-x.names | |
polygon(dat.poly[,1],dat.poly[,2],col=alpha(cols[[3]],0.5),border=NA) | |
} | |
if(plot.pts){ | |
points(dat.rand[,1],dat.rand[,2],col=alpha(dat.rand$y.under,0.5),pch=19) | |
} | |
} | |
if(!val) return(cat(out.txt)) | |
area.und | |
} |
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