How to create a table in R with 1s and 0s based on the presence of values from several other files

Question

I have five different text files that all contain 7 digit lines. I want to create a table that tells me, using 1s and 0s, whether the line is present in the file.

For example:

        file1.txt  file2.txt  file3.txt
xxxxxxx     1         0           1
xxxxxxx     0         1           1
xxxxxxx     1         1           1

I have little to no experience in R, or any kind of coding. Can someone help me? I can add more information if someone asks.

Answer 1

Assuming three files exist:

==> file1.txt <==
1111111
3333333

==> file2.txt <==
2222222
3333333

==> file3.txt <==
1111111
2222222
3333333

I would read the three files into separate dataframes:

file1=read.csv('file1.txt', header=FALSE)
file2=read.csv('file3.txt', header=FALSE)
file3=read.csv('file3.txt', header=FALSE)

Add a flag to each:

file1$file1.txt <- rep(1,nrow(file1))
file2$file2.txt <- rep(1,nrow(file2))
file3$file3.txt <- rep(1,nrow(file3))

Perform an outer join using merge , replace NA values with 0 and name rows with the values

merged=merge(merge(file1,file2, all=TRUE), file3, all=TRUE)
merged[is.na(merged)] <- 0
rownames(merged) <- merged[,1]
merged[,1] <- NULL

merged is now:

        file1.txt file2.txt file3.txt
1111111         1         0         1
2222222         0         1         1
3333333         1         1         1

See in particular: https://stat.ethz.ch/R-manual/R-devel/library/utils/html/read.table.html https://stat.ethz.ch/R-manual/R-devel/library/base/html/merge.html

And: How to join (merge) data frames (inner, outer, left, right)?