[R] two Y Axes (in the same scale) in ggplot2

[Jim Lemon]

On 05/09/2012 05:29 AM, wudadan wrote:
> Dear R users,
>
> I'm plotting housing prices in City A over past 30 years in ggplot2. The Xs
> are years since 1980. I have two housing price variables: new home prices
> and old home prices, both of them measured by $/sqft. I have searched
> related threads on multiple Y axes in ggplot2 and I understand that multiple
> Y axes in different scales are not possible. I'm wondering if it is possible
> to have multiple Y axes with the same scale in ggplot2, like in my case. If
> still not possible, is there a easy way to do it in R's default plot
> function? Thanks.
>
Hi Gary,
Perhaps twoord.plot (plotrix) will do what you want.

Jim