Label X Axis in Time Series Plot Using R

Label X Axis in Time Series Plot using R

Start with an example:

x.Date <- as.Date(paste(rep(2003:2004, each = 12), rep(1:12, 2), 1, sep = "-"))
x <- zoo(rnorm(24), x.Date)
plot(x)

If we want different tick locations, we can suppress the default axis plotting and add our own:

plot(x, xaxt = "n")
axis(1, at = time(x), labels = FALSE)

Or combine them:

plot(x)
axis(1, at = time(x), labels = FALSE)

You need to specify the locations for the ticks, so if you wanted monthly, weekly, etc values (instead of observations times above), you will need to create the relevant locations (dates) yourself:

## weekly ticks
plot(x)
times <- time(x)
ticks <- seq(times[1], times[length(times)], by = "weeks")
axis(1, at = ticks, labels = FALSE, tcl = -0.3)

See ?axis.Date for more details, plus ?plot.zoo has plenty of examples of this sort of thing.

How to set my own x axis labels for a time series plot in R?

We can use axis.Date to achieve this.

set.seed(1234)
aa <- sample(x=1:500,size = 804, replace = T)
Year_mon <- seq(from = as.Date("1950-01-15"), to = as.Date("2016-12-15"), by = "months")
plot(aa~Year_mon, type = "l", lty = 1)
axis.Date(1, at = as.Date(paste0(seq(1950, 2010, 10), "-01-01")), format="%Y")

Time-series plot: change x-axis format in R

In general, ts class is not a good fit for daily data. It is more suitable for monthly, quarterly and annual data.

For daily data, it would be easier to just convert it to zoo and plot:

library(zoo)
z <- read.zoo(mm17, format = "%Y/%m/%d")
plot(z$fullband, col = "red")

Note

We assume the mm17 is given as shown below.

Lines <- "   date fullband band1 
1 2015/1/14 109.0873 107.0733     
2 2015/1/15 110.1434 109.1999     
3 2015/1/16 109.8811 108.6232     
4 2015/1/17 110.4814 109.8164     
5 2015/1/18 110.1513 109.2764     
6 2015/1/19 110.3266 109.5860"
mm17 <- read.table(text = Lines)

Label X Axis in Multiple Time Series Plot

Unfortunately the default plot.zoo function internally changes par settings when you plot multiple plots and then automatically resets them when the function exists. When it resets the par parameters, this resets the plotting surface so subsequent calls to axis do not work. This function does not do this when only drawing a single time series.

There is no super easy/robust way to fix this. But, if you are feeling bold, you can perform a surgery on the function and insert new code in there. (This is not a generally recommended practice, but in this case it will make your life easier). I did this with zoo version 1.7-10. To make sure this will work for you, check that

body(plot.zoo)[19:20]

returns

do.call("title", title.args)(return(invisible(x)))

because we are going to add a line of code between those two statements. We will do that with

plot.zoo2<-plot.zoo
bl<-as.list(body(plot.zoo2))
bl<-c(
    bl[1:19], 
    quote(axis(1,at=ticks,labels=tick.lables)), 
    bl[20]
)
body(plot.zoo2)<-as.call(bl)

We've actually created a new function called plot.zoo2 that adds in a call to axis with our desired values. Now we call almost the same way we would the normal plotting function, but we just use our new version instead.

#define these before the plot() since we use them in our function now
times<-time(tp)
ticks<-seq(times[1],times[length(times)],by=90)
tick.labels<-c("Spring 2012","Summer 2012","Autumn 2012","Winter     2012","Spring 2013","Summer 2013","Autumn 2013","Winter 2013")

plot.zoo2(tp,screens=c(1,2,3),
    col=c("deepskyblue","seagreen3","orchid4"),
    ylim=c(0,1600),lwd="3",
    ylab=(expression("TP"~~(mu*"g/L"))),xlab=NA,xaxt="n",
    main="Seasonal variation of total phosphorus",
    cex.main=2)

Which gives

Distance between ticks in the X axis when plotting time-series in R

Thoughts:

base R

plot(Temp.media.de.las.medias ~ Inicio, dataset, col="black", ylim = c(0, 40), type = "l", lwd=2, xaxt='n')
ax <- as.Date(axTicks(1), origin = "1970-01-01")
axis(1, ax, format(ax, "%b %m"), cex.axis = .5)

Or if you prefer to have it year-aligned,

plot(Temp.media.de.las.medias ~ Inicio, dataset, col="black", ylim = c(0, 40), type = "l", lwd=2, xaxt='n')
ax <- seq(as.Date("2018-10-01"), as.Date("2019-04-01"), by = "3 months")
axis(1, ax, format(ax, "%b %m"), cex.axis = .5)

ggplot2

library(ggplot2)
ggplot(dataset, aes(Inicio, Temp.media.de.las.medias)) +
  geom_line() +
  scale_x_date(date_labels = "%b %m")

---

Data

dataset <- setDT(structure(list(Temp.media.de.las.medias = c(25.36, 25.39, 23.6, 22.53, 23.59, 20.7, 18.99, 18.37, 17.46, 16.13, 11.82, 14.52, 15.33, 13.39, 13.36, 13.41, 12.96, 10.85, 8.68, 7.72, 6.04, 8.96, 12.35, 13.52, 11.41, 9.31, 9.72, 12.29, 14.95, 14.64), Inicio = structure(c(17763, 17770, 17777, 17784, 17791, 17798, 17805, 17812, 17819, 17826, 17833, 17840, 17847, 17854, 17861, 17868, 17875, 17882, 17889, 17897, 17903, 17910, 17917, 17924, 17931, 17938, 17945, 17952, 17959, 17966), class = "Date")), row.names = c(NA,  -30L), class = c("data.table", "data.frame")))

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