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!

Gary


On Wed, May 9, 2012 at 7:26 AM, Duncan Murdoch <murdoch.duncan@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
>

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