Re: geo_vline: Error in example from ggplot2 book (p86)

[Dennis Murphy]

Hi:

> str(presidential)

'data.frame':   7 obs. of  4 variables:

 $ name : chr  "Nixon" "Ford" "Carter" "Reagan" ...

 $ start: Date, format: "1969-01-20" "1974-08-09" ...

 $ end  : Date, format: "1974-08-09" "1977-01-20" ...

 $ party: chr  "Republican" "Republican" "Democratic" "Republican" ...

Observe that start is a Date object - you want the numeric equivalent, because that's what is really plotted. This works for me in version 0.9.2.1:

unemp + geom_vline(aes(xintercept = as.numeric(start)), data = presidential)

Dennis

On Thu, Nov 1, 2012 at 11:13 AM, Brad Horn <bxh...@gmail.com> wrote:

The following code appears in the book (p86) and the book website to illustrates the use of geom_vline:

unemp <- qplot(date, unemploy, data=economics, geom="line", xlab = "", ylab = "No. unemployed (1000s)")

presidential <- presidential[-(1:3), ]

yrng <- range(economics$unemploy)

xrng <- range(economics$date)

unemp + geom_vline(aes(xintercept = start), data = presidential)

In my case, I geom_vline is generating the following error:

Error: Discrete value supplied to continuous scale

Logic says I shouldn't get this error.  Any help or insight is appreciated as I want to ensure the chart annotations are feasible.

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[WGray]

Thanks!!!