T03: Imputación de valores faltantes

Locked
AntonioG
Site Admin
Posts: 93
Joined: Sun Feb 18, 2018 2:17 pm
Contact:

T03: Imputación de valores faltantes

Post by AntonioG » Fri Oct 04, 2019 8:49 am

Code: Select all

install.packages("DMwR")  # for use of knnImputation.
require(DMwR)

x1<-3*rnorm(100)
x2<-round(abs(x1),2)
y2<-x2
y2[sample(1:100,25)]<-NA
M<-cbind(x1,y2)
sum(complete.cases(M))
https://en.wikipedia.org/wiki/Imputation_(statistics)

Code: Select all

#Central inputation
M1 <- centralImputation(M)
plot(x1,x2,type="p",pch=19)
plot(M1[,1],M1[,2],type="p",pch=19)
cbind(x1,y2,M1[,2])

Code: Select all

#knn imputation
M<-cbind(x1,x1,y2)
sum(complete.cases(M))

M2 <- knnImputation(M, 3)
plot(x1,x2,type="p",pch=19)
plot(M2[,1],M2[,3],type="p",pch=19)
Ind<-is.na(y2)
points(M2[Ind,1],M2[Ind,3],pch=19,col="red")

cbind(x1,y2,M2[,3])

AntonioG
Site Admin
Posts: 93
Joined: Sun Feb 18, 2018 2:17 pm
Contact:

Completar valores de píxeles faltantes

Post by AntonioG » Fri Oct 04, 2019 8:51 am

Code: Select all

library(jpeg)
library(DMwR)

plotIm<-function(x){
   x<-(x-min(x,na.rm=TRUE))/(max(x,na.rm=TRUE)-min(x,na.rm=TRUE))
   nr<-dim(x)[1]
   nc<-dim(x)[2]
   par(mai=c(0,0,0,0))
   plot(c(1,nc),c(1,nr), type='n', axes = FALSE, xlab = "", ylab = "")
   rasterImage(x, 0, 0, nc, nr,interpolate=FALSE)
   }

x<-readJPEG(file.choose())
Im<-x[,,1]
plotIm(Im)

nr<-dim(Im)[1]
nc<-dim(Im)[2]

rr<-sample(1:nr,nr*nc*0.10,replace = TRUE)
rc<-sample(1:nc,nr*nc*0.10,replace = TRUE)
Im[cbind(rr,rc)]<-NA

#rr<-sample(1:nr,nr*0.10,replace = TRUE)
#Im[rr,]<-NA

plotIm(Im)
par(bg="blue")
plotIm(Im)

w<-1
M<-rep(0,(2*w+1)^2)

for(i in 1:nr)
for(j in 1:nc){
   v<-rep(0,(2*w+1)^2)
   v[1]<-Im[i,j]
   k<-2
   for(k1 in (-w):w)
   for(k2 in (-w):w){
      if(k1==0 & k2==0) next
      if(i+k1>=1 & i+k1<=nr & k2+j>=1 & j+k2<=nc)
         v[k]<-Im[i+k1,j+k2]
      else
        v[k]<-NA
      k<-k+1
      }
   M<-rbind(M,v)
   }
M<-M[-1,]

M2 <- knnImputation(M, 3)

Im2<-matrix(M2[,1],nrow=nr,byrow=TRUE)
plotIm(cbind(Im,Im2))
Attachments
tex02.jpg
tex02.jpg (12.96 KiB) Viewed 22 times
tex01.jpg
tex01.jpg (11.73 KiB) Viewed 22 times
Lena.jpg
Lena.jpg (8.7 KiB) Viewed 22 times
Daubechie.jpg
Daubechie.jpg (7.63 KiB) Viewed 22 times

Locked

Who is online

Users browsing this forum: No registered users and 0 guests