r - Multiple x-axis labels for time-series data -

i able plot time-series data using ggplot2. however, want highlight seasonal information alongwith time-series data.

here's code:

library(zoo) library(ggplot2)  <- read.table(text = "        season quarter  sales        season1  2014q1  20         season1  2014q2  40         season1  2014q3  60         season1  2014q4  80         season2  2015q1  30         season2  2015q2  40         season2  2015q3  80         season3  2015q4  90         season3  2016q1  100         season3  2016q2  120         season3  2016q3  140      ", header = true, sep = "") a$quarter<-as.yearqtr(a$quarter) a$quarter<-as.date(a$quarter)  ggplot(data=a,aes(x=quarter, y=sales)) +        geom_line() 

this works in able draw time-series data.

now, want label constitutes season 1, 2 etc. 1 way use color or linetype. however, doesn't seem work because breaks continuity of time-series.

# doesn't work... ggplot(data=a,aes(x=quarter, y=sales)) +        geom_line(aes(linetype=season)) 

on other hand, how excel plots graph in just 2 clicks. creates beautiful graph shows seasonal information on x-axis along dates. creates 3-layered x-axis.

i have 2 questions on topic:

question 1: using ggplot, how can use linetype (or color) in ggplot create continuous graph (i.e. without breaks)? i'd prefer linetype on color. as example , answer comment: here's graph created using different set of data.

df <- data.frame(x = 1:3, y = 1:3, z = c(1,3,5)) ggplot(df, aes(x, y, color = factor(z))) +        geom_line(aes(group = 1)) 

i unable replicate above behavior time-series data. here's graph got above code:

question 2: using ggplot, how can create multi-level x-axis (similar excel did me) shows seasonal information dates? {please see excel graph created.} not want create legend using option. want clarify i'd appreciate if don't use hacking methods applying annotate (or possibly geom_text) methods put these multi-level labels adjusting , re-adjusting x- , y- values fit them. because defeats purpose of using programming language draw graph, , won't work data change.

if have questions, please let me know. i'd appreciate thoughts. absolute beginner ggplot2. it's been 5 days since have transitioned excel , stata ggplot. so, apologize if question basic.

i researched topic on , couldn't close enough. instance, this thread talks changing ticks, not looking for.

you can quite recreate intent of excel plot this:

library(plyr) ss <- ddply(a, .(season), summarize, date = min(quarter)) ss$date <- as.numeric(ss$date)  ggplot(data=a,aes(x=quarter,y=sales)) +   geom_line() +   geom_vline(data = ss, aes(xintercept = date), colour = "grey50") +   geom_text(data = ss, aes(x = as.date(date), y = inf, label = season),              hjust = -0.1, vjust = 1.1) 

one workaround break in line when using colours plot continuous grey line in addition colour lines:

ggplot(data=a,aes(x=quarter,y=sales)) +   geom_line(colour = "grey80") +   geom_line(aes(colour = season)) +   geom_vline(data = ss, aes(xintercept = date), colour = "grey50") +   geom_text(data = ss, aes(x = as.date(date), y = inf, label = season),              hjust = -0.1, vjust = 1.1)