Hello!
# I have 3 vectors of values:
values1<-rnorm(10)
values2<-rnorm(10)
values3<-rnorm(10)
# In real life, all 3 vectors have a length of 25
# I create all possible combinations of 4 based on 10 elements:
mycombos<-expand.grid(1:10,1:10,1:10,1:10)
dim(mycombos)
# Removing rows that contain pairs of identical values in any 2 of
these columns:
mycombos<-mycombos[!(mycombos$Var1 == mycombos$Var2),]
mycombos<-mycombos[!(mycombos$Var1 == mycombos$Var3),]
mycombos<-mycombos[!(mycombos$Var1 == mycombos$Var4),]
mycombos<-mycombos[!(mycombos$Var2 == mycombos$Var3),]
mycombos<-mycombos[!(mycombos$Var2 == mycombos$Var4),]
mycombos<-mycombos[!(mycombos$Var3 == mycombos$Var4),]
dim(mycombos)
# I want to write sums of elements from values1, values2, and values 3
whose numbers are contained in each column of mycombos. Here is how I am
going it now - using a loop:
mycombos$sum1<-NA
mycombos$sum2<-NA
mycombos$sum3<-NA
for(i in 1:nrow(mycombos)){
mycombos$sum1[i]<-values1[[mycombos[i,"Var1"]]] +
values1[[mycombos[i,"Var2"]]] + values1[[mycombos[i,"Var3"]]] +
values1[[mycombos[i,"Var4"]]]
mycombos$sum2[i]<-values2[[mycombos[i,"Var1"]]] +
values2[[mycombos[i,"Var2"]]] + values2[[mycombos[i,"Var3"]]] +
values2[[mycombos[i,"Var4"]]]
mycombos$sum3[i]<-values3[[mycombos[i,"Var1"]]] +
values3[[mycombos[i,"Var2"]]] + values3[[mycombos[i,"Var3"]]] +
values3[[mycombos[i,"Var4"]]]
}
head(mycombos);tail(mycombos)
# It's going to take me forever with this loop. Is there a faster way of
doing the dame thing? Thanks a lot!
--
Dimitri Liakhovitski
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