The x axes of my graph are defined as follow: Dmmggyyyy, where D is a char. Due to the fact that I´m working on yearly basis when I print the graph the x axes texts are unreadable. Is possible to use a regex and group datas from D01012015 to D02012015 etch. and call them January, February... The source code of my plot is:
df <- melt(data)
pl <- ggplot(df, aes(time, price,group=factor(xxx))) +
geom_line(aes(color=factor(xxx)))+
theme(axis.text.x element_blank())