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I am a beginner in ggplot2. I am unable to use date_minor_breaks to show quarterly "ticks" on x-axis.

Here's my code:

x<-c(seq(1:12))
time<-c("2010Q1","2010Q2","2010Q3","2010Q4","2011Q1","2011Q2", "2011Q3","2011Q4","2012Q1","2012Q2","2012Q3","2012Q4")
z<-data.frame(type = x,time = time)
z$time = as.yearqtr(z$time)
z$time = as.Date(z$time)
ggplot(data = z, aes(x=time,y=type)) +
geom_point() + 
scale_x_date(date_labels = "%Y",date_minor_breaks = "3 months",name = "Year") +
theme_tufte() +
theme(legend.position = "none")

I researched this topic on SO Formatting dates with scale_x_date in ggplot2 and on https://github.com/hadley/ggplot2/issues/542, and found that there were some issues reported on this topic. However, I didn't quite follow the conversation about changes to ggplot2 because it's been only 6 days since I started using ggplot2.

Here's the graph I got (it doesn't have any ticks)...

enter image description here

Here's a sample graph with "tick marks" generated from Excel. Please ignore values because my point of creating this Excel chart is to demonstrate what I am looking for--i.e. "quarterly ticks". I'd appreciate your help.

enter image description here

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watchtower
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2 Answers2

7

You may have to make major breaks every three months and then pad your labels with blanks to give the illusion of major (labeled) and minor (unlabeled) ticks. See this answer for another example.

First manually make the breaks for the tick marks at every quarter.

breaks_qtr = seq(from = min(z$time), to = max(z$time), by = "3 months")

Then make the year labels and pad these labels with three blanks after each number.

labels_year = format(seq(from = min(z$time), to = max(z$time), by = "1 year"), "%Y")
labs = c(sapply(labels_year, function(x) {
    c(x, rep("", 3))
    }))

Now use the breaks and the labels with the labels and breaks arguments in scale_x_date. Notice that I'm not using date_labels and date_breaks for this.

ggplot(data = z, aes(x=time,y=type)) +
    geom_point() + 
    scale_x_date(labels = labs, breaks = breaks_qtr, name = "Year") +
    theme_tufte() +
    theme(legend.position = "none")

enter image description here

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aosmith
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0

You should also define your (major) date breaks:

ggplot(data = z, aes(x=time, y=type)) +
  geom_point() + 
  scale_x_date(date_breaks = "1 year", name = "Year", date_minor_breaks="3 months",
               limits = c(as.Date(as.yearqtr("2009Q4")),
                          as.Date(as.yearqtr("2013Q2"))),
               expand=c(0,0), date_labels = "%Y") +
      theme(legend.position = "none")

And some other "fancy" stuff to align the minor ticks with the major ticks (I guess there a better ways to do this, but this works).

enter image description here

Huub Hoofs
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  • Where are the ticks? I believe what you are seeing is gridline and not the tick. Please see the Excel version in my question above--it doesn't have gridlines but does have ticks... – watchtower Aug 31 '16 at 20:38
  • Than you could define date_breaks as 3 months and than manually define the labels and leave blanks – Huub Hoofs Aug 31 '16 at 20:57