Subsetting in R using OR condition with strings

Question

I have a data frame with about 40 columns, the second column, data[2] contains the name of the company that the rest of the row data describes. However, the names of the compani

Answer 1

First of all (as Jonathan done in his comment) to reference second column you should use either data[[2]] or data[,2]. But if you are using subset you could use column name: subset(data, CompanyName == ...).

And for you question I will do one of:

subset(data, data[[2]] %in% c("Company Name 09", "Company Name"), drop = TRUE) 
subset(data, grepl("^Company Name", data[[2]]), drop = TRUE)

In second I use grepl (introduced with R version 2.9) which return logical vector with TRUE for match.

Answer 2

A couple of things:

1) Mock-up data is useful as we don't know exactly what you're faced with. Please supply data if possible. Maybe I misunderstood in what follows?

2) Don't use [[2]] to index your data.frame, I think [,"colname"] is much clearer

3) If the only difference is a trailing ' 09' in the name, then simply regexp that out:

R> x1 <- c("foo 09", "bar", "bar 09", "foo")
R> x2 <- gsub(" 09$", "", x1)
[1] "foo" "bar" "bar" "foo"
R> 

Now you should be able to do your subset on the on-the-fly transformed data:

R> data <- data.frame(value=1:4, name=x1)
R> subset(data, gsub(" 09$", "", name)=="foo")
  value   name
1     1 foo 09
4     4    foo
R> 

You could also have replace the name column with regexp'ed value.