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### Micro Note No. I on S-Plus Graphics
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# There are some tools in S-Plus that are so called "High Level" graphics.
# These just do some concrete job, like plot a histogram.

z<-rnorm(1000)
histogram(z)

# This gives you a picture. It's OK this time, but in general 
# histograms are pretty lame --- they often conceal more than they reveal.

# The reason for mentioning this function is to underscore that 
# behind the sceens, lives a more fundamental function named "plot".

# Here is a plain-vanilla example of the plot function:

x<-1:10
y<-x^2
plot(x,y)

# Plot has lots of options you can explore.
# Plot also lets you "keep doing stuff to it."
# For example, lets put a vertical line at 5 and a hoizonal  line at 25

abline(v=5)
abline(h=10)

# Or now, add some text a little to the upper right of (6,36)

text(6.2, 36.3, "HERE")

# Using more primatives like these you can bulid all sorts of plots, but this is more of
# a presentation issue than an analysis issue.

#Some more examples?

xs=c(6,10)
ys=c(36,100)
lines(xs,ys)

# Now you have almost everyting you need to know to draw the Mona Lisa in S-Plus
# The only extra thing you need is a way to put down dots of varrying intensities or colors.

# You should use help(plot) to explore some of the very many options.

# Final point --- what stops one plot and starts another?
# When you start a new plot  --- or something call calls plot()  --- you get a new plot.
# Note, histogram and qqplot are "high level" tools that call plot --- and wipe out what you have in
# your old plot.

# You should also check out "devices" using help(devices).
# This will show you how to save your plots to pdf or other kinds of files. 
# In windows we usually side step this just by doing cut-and-paste.