How to conduct LOCF inputation in R; library{zoo}

Let us assume that weight has been measured on 624 patients for 4 distinct time points: M0, M1, M3 and M6

``` {r} 

library(zoo)

#start by creating the vectors which includes the variables we want to use for imputation

WeightImpute<-cbind(MetSData$POIDS_M0,MetSData$POIDS_M1,MetSData$POIDS_M3,MetSData$POIDS_M6)

#then we rename the columns

colnames(WeightImpute)=c("w0", "w1", "w3", "w6")

#creating a replicate array to be used within the for loop

WeightImputeF=WeightImpute

#creating an object which is equal to the number of rows within our array (624)

n=dim(WeightImpute)[1]

#creating a counter (1:624) labeling it index

index=which(!is.na(WeightImpute[,1]))

#creating a for loop using the na.locf function from library (zoo) that will carry on the LOCF. ATTENTION: the imputation will be carry out by column, that is the `i' is placed in the row part of the argument 

for(i in index){WeightImputeF[i,]=na.locf(WeightImpute[i,])}

WeightImputeF

```