get-context.R

getContext <- function(re, data=sampleData) {
    reWithContext <- paste0(".{0,10}", re, ".{0,10}")
    context <- data[grep(reWithContext, data$text, perl=T),]
    m <- regexpr(reWithContext, context$text, perl=T)
    cbind(context, data.frame(context=regmatches(context$text, m)))
}

writeOut <- function(df, fname) {
    f <- file(fname, 'wt')
    for (rownum in 1:nrow(df)) {
        row <- df[rownum, ]
        write(paste(row.names(row), row$source, row$context, sep='\t'), f)
    }
    close(f)
}