[R] abline with zoo series

[Erin Hodgess]

Hello!  Happy Thanksgiving to those who are celebrating.

I have a zoo series that I am plotting, and I would like to have some
vertical lines at certain points, to indicate US business cycles.  Here is
an example:

app1 <- get.hist.quote(instrument="appl",
start="1985-01-01",end="2016-08-31", quote="AdjClose", compression="m")
#Fine
plot(app1,main="Historical Stock Prices: Apple Corporation")
#Still Fine
#Now I want to use abline at July 1990 and March 1991 (as a start) for
business cycles.  I tried v=67 and v="1990-07", no good.

I have a feeling that it's really simple and I'm just not seeing it.

Any help much appreciated.

Thanks,
Erin


-- 
Erin Hodgess
Associate Professor
Department of Mathematical and Statistics
University of Houston - Downtown
mailto: erinm.hodgess at gmail.com

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