[R] mean on a plot

[Joshua Wiley]

Hi Romzero,

This gets the job done, though it is not the most elegant solution
ever (for those I'd take a look at the ggplot2 or lattice packages).


## Read in data
la <- read.table(textConnection("
Days    Weight
0       178.00
0       250.00
0       242.00
0       239.00
0       223.00
0       188.00
0       237.00
0       212.00
0       273.00
0       191.00
0       173.00
0       233.00
0       227.00
0       253.00
0       232.00
4       177.00
4       249.00
4       241.00
4       238.00
4       222.00
4       188.00
4       236.00
4       211.00
4       272.00
4       190.00
4       172.00
4       232.00
4       226.00
4       252.00
4       231.00"), header = TRUE)
closeAllConnections()

## calculate mean by day
tmp <- c(with(la, by(Weight, Days, mean)))
## your plot
plot(Weight ~ Days, data = la)
## add in the daily means
points(x = as.numeric(names(tmp)), y = tmp, col = "blue", cex = 2, pch = 16)

Cheers,

Josh

On Sun, Nov 7, 2010 at 10:53 AM, romzero <romzero at yahoo.it> wrote:
>
> Hi, i need to draw a plot with means of values, reading a table from
> datafile.
>
> Example of datafile:
>
> Days    Weight
> 0       178.00
> 0       250.00
> 0       242.00
> 0       239.00
> 0       223.00
> 0       188.00
> 0       237.00
> 0       212.00
> 0       273.00
> 0       191.00
> 0       173.00
> 0       233.00
> 0       227.00
> 0       253.00
> 0       232.00
> 4       177.00
> 4       249.00
> 4       241.00
> 4       238.00
> 4       222.00
> 4       188.00
> 4       236.00
> 4       211.00
> 4       272.00
> 4       190.00
> 4       172.00
> 4       232.00
> 4       226.00
> 4       252.00
> 4       231.00
>
> if i use "plot(Weight~Days, data=la)" the result is this
> http://r.789695.n4.nabble.com/file/n3031068/weightm.jpg
>
> how can i draw a plot with means for each days?
>
> tnx for help :)
>
> --
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> Sent from the R help mailing list archive at Nabble.com.
>
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>



-- 
Joshua Wiley
Ph.D. Student, Health Psychology
University of California, Los Angeles
http://www.joshuawiley.com/