Lattice, combine histogram and line graph

Hi Jim,

Some example data would help us.  I typically think of a histogram as
the frequency of values falling within a certain range (determined by
bins).  Since they are univariate plots, I'm not sure how you are
planning on adding a line graph to that.  If you just want bars of the
average gasoline price at different years, perhaps something along
these lines would work for you:

## Load required packages
require(lattice)
require(latticeExtra)

## Sample Data
dat <- data.frame(year = 1996:2010,
  x1 = rnorm(15, 3, .2), x2 = rnorm(15, 200, 1))

## Base xyplot (not a histogram) adding a layer with different y axis
xyplot(x1 ~ year, data = dat, type = "h") +
  as.layer(xyplot(x2 ~ year, data = dat, type = "l", col = "black"),
  y.same = FALSE)

## See
?xyplot
?as.layer
?hist # for info about histograms

HTH,

Josh

On Sun, Jan 9, 2011 at 5:13 PM, Jim Burke <j.burke at earthlink.net> wrote:
  

Hello everyone,

I have a simple histogram of gasoline prices going back a few years that I
want to insert a line graph of consumer price index (cpi) over the
histogram.  I have looked through the "Lattice" book by Deepayan Sarkar but
don't see anything there. How might this be done? An example would be
wonderful.

Current code snippet follows. For example additional field to add as a line
graph would be a cpi calculation like "gas_data$regular * (2010_cpi /
gas_data$year )".

xyplot( regular ~ as.Date(gas_data$dates,"%b %d, %Y") , data = gas_data,
      type = c("g", "h" ))

Thanks,
Jim Burke