It does not test the first column, but a vector must have consecutive indices.
Since you did not assign a value, R inserts a missing value. If you don't want
to see it use
> results.pc.all[, -1]
[,1] [,2]
results.2 1 2
results.3 2 3
-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352
-----Original Message-----
From: R-help [mailto:r-help-boun...@r-project.org] On Behalf Of Brittany Demmitt
Sent: Monday, June 20, 2016 12:15 PM
To: r-help@r-project.org
Subject: [R] loop testing unidentified columns
Hello,
I want to compare all of the columns of one data frame to another to see if any
of the columns are equivalent to one another. The first column in both of my
data frames are the sample IDs and do not need to be compared. Below is an
example of the loop I am using to compare the two data frames that counts the
number of equivalent values there between two columns. So in this example the
value of 3 means that all three observations for the two columns being compared
were equivalent. The loop works fine but I do not understand why it tests the
first column of the sample IDs providing “NA” for the sum of matching when my
loop is specifying to only test columns 2-3.
Thank you!
#create dataframe A
A = matrix(c("a",3,4,"b",5,7,"c",3,7),nrow=3, ncol=3,byrow = TRUE)
A <- as.data.frame(A)
A$V2 <- as.numeric(A$V2)
A$V3 <- as.numeric(A$V3)
str(A)
#create dataframe B
B = matrix(c("a",1,1,"b",6,2,"c",2,2),nrow=3, ncol=3,byrow = TRUE)
B <- as.data.frame(B)
B$V2 <- as.numeric(B$V2)
B$V3 <- as.numeric(B$V3)
str(B)
results.2 <- numeric()
results.3 <- numeric()
#compare columns to identify those that are identical in the two dataframes
for(i in 2:3){
results.2[i] <- sum(A[,2]==B[,i])
results.3[i] <- sum(A[,3]==B[,i])
results.pc.all <- rbind(results.2,results.3)
}
results.pc.all
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______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
