How to get tick marks between the bars in R?

Question

I'd like to get the tick marks between consumption bars, such as in http://hante.home.xs4all.nl/plugwise_dagoverzicht_281009_2.jpg .

It's more logical to get the consumption between two dates, or two times...

However, I don't see how to do that in R. Anybody?

I do have such an example table, called data:

       date  nombre  delta 
 2014-02-01       0      0 
 2014-02-08     120    120 
 2014-02-15     205     85 
 2014-02-22     280     75 
 2014-02-29     350     70 

The code I managed so far to write down is:

data$date <- as.POSIXct(data$date, format = "%Y-%m-%d")
data <- data[-2]
barplot(height=data[,2], names=data[,1], las=2)

But the "ticks" are just below the bars... as you can see on http://imgur.com/0WE7ouI .

Answer 1

You didn't provide any code whatsoever. How is your data represented? How are you plotting the bars?

If you are using package lattice 's barchart(..., horizontal=FALSE) , you can manually provide new axis tickslabels using the argument scales=list(x=list(at=seq_len(numBars+1) - 0.5, labels=yourLabels))) where numBars is the number of bins on your x-axis. See ?barchart .

If you are using the more primitive barplot , you can draw an offset axis yourself:

mids <- barplot(x, axisnames=FALSE)
axis(1, at = mids - (mids[2]-mids[1])/2, labels = yourLabels)

Either way, obviously you can shift to the right instead by changing offset signs, or add both outside ticks for numBins +1 labels.

EDIT : With the code+data you added in your edit:

mids <- barplot(height=data[,2], axisnames=FALSE)
axis(1, at = mids - (mids[2]-mids[1])/2, labels = data[,1], las=2)

or eg writing it and adding an end date:

mstep <- (mids[2] - mids[1]) / 2
axis(1, at=c(mids[1] - mstep, mids + mstep), labels=c(data[,1], endDate), las=2)