CODEWITHSUNDEEP
r
Jesse001
Jesse001

Reputation: 924

Removing columns from a matrix using a list of column names

I'm attempting to remove all colSums !=0 columns from my matrix. Using this post I have gotten close. 

data2<-subset(data, Gear == 20) #subset off larger data matrix
 i <- (colSums(data2[,3:277], na.rm=T) != 0) #column selection in this line limits to numeric columns only 
 data3<- data2[, i]  #select only columns with non-zero colSums

This creates a vector, i, that properly identifies the columns to be removed using a logical True/False. However, the final line is removing columns by some logic other than my intentional if true then include if false then exclude. The goal: remove all columns in that range that have a colSums == 0 . The problem: my current code does not seem to properly identify said columns Suggestion as to what I'm missing?

Update: Adding dummy data to use: 

a<-matrix(1:10, ncol = 10,nrow=10)
a
a[,c(3,5,8)]<-0
a
i <- (colSums(a, na.rm=T) != 0) 
 b<- a[, i]

it works well here, so I'm not sure why it won't work above on real data.

Upvotes: 1

Views: 83

Answers (1)

akrun
akrun

Reputation: 887851

We can get the column names from the colSums and concatenate with the first two column names, which was not used for creating the condition with colSums to select the columns of interest

data[c(names(data)[1:2], names(which(i1)))]

Upvotes: 1

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