[R] Two Y axes (same scale) in ggplot2 or plot

[Duncan Murdoch]

On 09/05/2012 10:46 AM, Gary Dong wrote:
> Thanks, Duncan.
>
> I tried axis(). It appears it allows you to add an axis, but does not 
> say you can plot a second Y in the graph. Maybe I'm understanding it 
> correctly. Any help will be appreciated!

I don't understand what you want.  Could you give an example that comes 
close, and explain what is wrong with it?

Duncan Murdoch

>
> Gary
>
>
> On Wed, May 9, 2012 at 7:26 AM, Duncan Murdoch 
> <murdoch.duncan at gmail.com <mailto:murdoch.duncan at gmail.com>> wrote:
>
>     On 08/05/2012 3:23 PM, Gary Dong 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.
>
>
>     In base graphics, you can have as many axes as you like,
>     displaying anything.  Use the axis() function.  See ?axis for the
>     arguments that determine placement, ticks, etc.
>
>     I would guess the same flexibility is there in ggplot2, but I
>     don't know how to do it.
>
>     Duncan Murdoch
>
>