R help - Feb 2008 - ggplot2 & ribbon

I would like to be able to shade between two lines using ggplot2 (with
faceting too).  But, despite reading all the documentation on the website,
cant figure out how to do it  (either because i am a novice or idiot - or,
of course, possibly both)

My data looks is readership of paid & free newspapers in london by age since
1994.  The structure is

reading.melt <-
structure(list(Date = structure(c(9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757, 9100, 11292, 11657, 12022,
12387, 12753, 13118, 13483, 13757), class = "Date"), Geog =
structure(c(1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = "London", class
"factor"),
    Type = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L,
    2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
    1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L,
    1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 1L,
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
    2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L,
    2L, 2L, 2L, 2L, 2L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L,
    2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("Paid",
"Total"
    ), class = "factor"), variable = structure(c(1L, 1L, 1L,
    1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L,
    2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L,
    2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L,
    3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L,
    4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 5L, 5L, 5L,
    5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 6L, 6L, 6L,
    6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L, 6L
    ), .Label = c("Age.15.24", "Age.25.34",
"Age.35.44", "Age.45.54",
    "Age.55.64", "Age.65."), class = "factor"),
value = c(57.6,
    54.7, 44.9, 51.1, 43.5, 44.8, 44, 50, 39.6, 57.6, 54.7, 50.4,
    57.3, 55, 57.5, 52.5, 60.9, 59.7, 60.7, 51.9, 52.8, 53.5,
    43.5, 40.8, 47.5, 42.7, 34.4, 60.7, 51.9, 57.6, 58.7, 50.2,
    51.3, 59, 55.2, 56.5, 65.3, 56.9, 50.5, 54.9, 48.3, 53.3,
    43.7, 50.4, 42.2, 65.3, 56.9, 53.2, 58.1, 52.7, 57.6, 52.1,
    58.2, 55.4, 69.2, 67.2, 52.6, 61.4, 56.1, 49, 54.8, 51.5,
    45.2, 69.2, 67.2, 55.2, 63.6, 57.6, 53.6, 60.5, 57.2, 58.1,
    70.7, 64.5, 58.2, 64.7, 57.6, 62.1, 64.3, 61.8, 59.9, 70.7,
    64.5, 58.7, 66.3, 58.4, 67.2, 66.9, 63.5, 65.3, 67.5, 67.8,
    66.4, 70.2, 60.2, 64, 59.4, 59.7, 57.8, 67.5, 67.8, 66.4,
    70.3, 60.3, 64.7, 60, 61.1, 60.3)), .Names = c("Date",
"Geog",
"Type", "variable", "value"), row.names = c(NA,
-108L), class = "data.frame
")

I then run ...

p<-ggplot(reading.melt,aes(x=Date,y=value))
p+geom_path(aes(colour=Type),size=2)+facet_grid(variable~.)

but can't figure out
(1) How to add a transparent shade between the Paid & Total lines.  I've
tried the ribbon function, but cant seem to get it to shade between the
lines
(2) Add a left justified title to the chart

Any help very grateful received

thanks

simeon

	[[alternative HTML version deleted]]

> p<-ggplot(reading.melt,aes(x=Date,y=value))
> p+geom_path(aes(colour=Type),size=2)+facet_grid(variable~.)
>
> but can't figure out
> (1) How to add a transparent shade between the Paid & Total lines. 
I've
> tried the ribbon function, but cant seem to get it to shade between the
> lines
To do this you'll need the data in a different format

df <- cast(reading.melt, ... ~ Type)

Then add on a ribbon as follows

p <- ggplot(reading.melt,aes(x=Date)) +
 facet_grid(variable ~ .)  +
 geom_ribbon(aes(min = Paid, max=Total), data=df, fill=alpha("black",
0.1), colour=NA) +
 geom_path(aes(colour=Type ,y=value))
> (2) Add a left justified title to the chart
p + opts(title = "My title")

adds a title, and to left justify it, you need to use grid to modify it:

grid.edit("title", x=unit(0, "npc"), hjust=0)

Hadley

-- 
http://had.co.nz/