228 Text Mining and Visualization: Case Studies Using Open-Source Tools
# substitute the isolated "@" by "at"
twt$text<-gsub("(ˆ|[[:space:]])(@)([[:space:]])","\\1at\\3",twt$text)
# transform @<number> into "at <number>":
twt$text<-gsub("(ˆ|[[:space:]])(@)([$]?[0-9.]+)([[:space:]]|[[:punct:]]|$)","\\1at
\\3\\4",twt$text),→
# substitute "+<number>" by "more <number>"
twt$text<-gsub("(ˆ|[[:space:]])([+])([$]?[.]?[[:digit:]]+)","\\1more
\\3",twt$text),→
# substitute "-<number>" by "less <number>"
twt$text<-gsub("(ˆ|[[:space:]])([-])([$]?[.]?[[:digit:]]+)","\\1less
\\3",twt$text),→
# substitute "˜<number>" by "nearly <number>"
twt$text<-gsub("(ˆ|[[:space:]])([˜])([[:space:]]?)([$]?[.]?[[:digit:]]+)","\\1nearly
\\4",twt$text),→
# substitute "#<number>" by "number ...