Merging multiple text files in R with a constraint

Question

I have 10 text files containing 1000\'s of rows.

Example: First File:

V1  V2
1   2
2   3
10 20
1   4    
.....

Second file:

<

Answer 1

Try this example:

#dummy files
file1 <- read.table(text="V1  V2
1   2
2   3
10 20
1   4   ",header=TRUE)
file2 <- read.table(text="
V1  V2
1   2
8   10",header=TRUE)

#make list of files - this can be done by lapply(list.files(),read.table)
all_files <- list(file1,file2)

#get unique pairs
unique_pairs <- unique(do.call(rbind,all_files))
#add new pair that is not in file1 and file2
unique_pairs <- rbind(unique_pairs,c(33,22))

#loop through pairs and files
result <- sapply(1:nrow(unique_pairs),
                 function(x)
                   sapply(all_files,function(myfile){
                     #merge pair with file then check number of rows
                     d <- merge(myfile,unique_pairs[x,,drop=FALSE])
                     ifelse(nrow(d)==0,0,1)
                   }))

#output
cbind(unique_pairs,t(result))
# V1 V2 1 2
# 1   1  2 1 1
# 2   2  3 1 0
# 3  10 20 1 0
# 4   1  4 1 0
# 6   8 10 0 1
# 61 33 22 0 0