CODEWITHSUNDEEP
rchartsbar-chart
dns1986
dns1986

Reputation: 33

Horizontal bar-chart: mis-matched axis units

I am attempting to create a rotated bar-chart with years on the y-axis. Certain years have a value (i.e., a bar), the rest are zero.

For some reason, when I add a y-axis with the years, there is a mis-match between the bar and the year the value reflects. I'd be grateful if someone could explain why this occurs and how to get around it.

Here is a subset of my data:

x <- c(0, 0, 0, 0, 0, 0, 0, 1.82, 0, 0, 0, 0, 0, 1.04, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1.28, 0, 0, 0, 0, 0, 0, 0, 0, 1.43, 1.55, 0, 0, 0, 0, 0, 0, 0, 1.22, 1.14, 2.05, 0, 0, 0, 0, 0)
y <- 1860:1909

barplot(x, horiz=TRUE, axes=F)
axis(2, at=seq(1, 50, 2), labels=seq(1860, 1909, 2), las=2)

The first value occurs in 1867, but appears at 1868 on the chart. I believe the data are fine because x[8] returns 1.82 and y[8] returns 1867, which is correct. The mis-match amplifies through the series; indeed the last three bars plot above the y-axis.

Perhaps I have missed something fundamental... many thanks in advance.

Upvotes: 2

Views: 50

Answers (1)

MrFlick
MrFlick

Reputation: 206232

barplot() doesn't plot the bars on integer values. It returns the values that it used as a matrix and then you can use that to label the axes

bp <- barplot(x, horiz=TRUE, axes=F)
axis(2, at=bp[,1][seq(1,50, by=2)], labels=seq(1860, 1909, 2), las=2)

Upvotes: 2

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