R help - Feb 2003 - Overlaying a moving average curve on top of a barplot

I''m using standard barplot (Windows version 1.6.2 of R) to represent a
certain weekly metric "v" and I would like to properly overlay on top
of it its moving average "mean.8" (window of 8 weeks). I must be doing
something wrong since the moving average (using "lines")
doesn''t overlay properly, i.e., both x-scales do not match!
 
...
barplot(v[8:length(v)], col=7)
lines(mean.8[1:length(mean.8)],   lty=1, lwd=2, col=2)
...
 
How do I make sure that both graphics are in synch as far as the x-scale and
y-scales are concerned?
 
Thanks,

José A. S. Alegria

 

 

 

	[[alternate HTML version deleted]]

Jose Santos Alegria wrote:
>I'm using standard barplot (Windows version 1.6.2 of R) to represent a
certain weekly 
>metric "v" and I would like to properly overlay on top of it its
moving
average "mean.8" 
>(window of 8 weeks). I must be doing something wrong since the moving
average (using >"lines") doesn't overlay properly, i.e., both
x-scales do
not match!

Have you considered using "filter"? I made a somehov similiar plot
this way:
(prec being a data frame with 'columns' date with dates of measurements
and
prec, precipitation at the actual date)

<code>
  plot(prec)
  lines(prec$date,filter(prec$value,c(0.25,0.25,0.25,0.25))) 
</code>

Points showing actual measurements and a four periods moving average  as a
line.


Hope this helps.

Morten

-- 
Morten Sickel
Norwegian Radiation Protection Authority
http://www.nrpa.no

My problem is not with "plot()" but with "barplot()"! I
guess it may have to do with the fact that the barplot's bars have a
non-negligible width and the moving average line not! Is it?

Jos? A. S. Alegria
 
 


-----Original Message-----
From: Morten Sickel [mailto:Morten.Sickel at nrpa.no] 
Sent: segunda-feira, 3 de Fevereiro de 2003 11:43 AM
To: Jos? Santos Alegria; R help (E-post)
Subject: RE: [R] Overlaying a moving average curve on top of a barplot


Jose Santos Alegria wrote:
>I'm using standard barplot (Windows version 1.6.2 of R) to represent a
certain weekly 
>metric "v" and I would like to properly overlay on top of it its
moving
average "mean.8" 
>(window of 8 weeks). I must be doing something wrong since the moving
average (using >"lines") doesn't overlay properly, i.e., both
x-scales do not match!

Have you considered using "filter"? I made a somehov similiar plot
this way: (prec being a data frame with 'columns' date with dates of
measurements and prec, precipitation at the actual date)

<code>
  plot(prec)
  lines(prec$date,filter(prec$value,c(0.25,0.25,0.25,0.25))) 
</code>

Points showing actual measurements and a four periods moving average  as a line.


Hope this helps.

Morten

-- 
Morten Sickel
Norwegian Radiation Protection Authority
http://www.nrpa.no

>-----Original Message-----
>From: r-help-admin at stat.math.ethz.ch 
>[mailto:r-help-admin at stat.math.ethz.ch] On Behalf Of Jos? 
>Santos Alegria
>Sent: Monday, February 03, 2003 5:30 AM
>To: r-help at stat.math.ethz.ch
>Subject: [R] Overlaying a moving average curve on top of a barplot
>
>
>I'm using standard barplot (Windows version 1.6.2 of R) to 
>represent a certain weekly metric "v" and I would like to 
>properly overlay on top of it its moving average "mean.8" 
>(window of 8 weeks). I must be doing something wrong since the 
>moving average (using "lines") doesn't overlay properly, i.e.,
>both x-scales do not match!
> 
>...
>barplot(v[8:length(v)], col=7)
>lines(mean.8[1:length(mean.8)],   lty=1, lwd=2, col=2)
>...
> 
>How do I make sure that both graphics are in synch as far as 
>the x-scale and y-scales are concerned?
> 
>Thanks,
>
>Jos? A. S. Alegria
The problem that you are having is that you need to get the bar
midpoints from barplot() in order to use those values as the x
coordinate values for lines().  barplot() returns the bar midpoints as
an invisible vector (or matrix where appropriate).

Modify your code to:

mp <- barplot(v[8:length(v)], col=7)
lines(mp, mean.8[1:length(mean.8)],   lty=1, lwd=2, col=2)

This puts the bar midpoints (x axis values) in mp, which you can then
use for lines().

HTH,

Marc

It makes sense and it works!

Thanks and best regards,

Jos? A. S. Alegria
 
 


-----Original Message-----
From: Marc Schwartz [mailto:MSchwartz at MedAnalytics.com] 
Sent: segunda-feira, 3 de Fevereiro de 2003 4:18 PM
To: Jos? Santos Alegria; r-help at stat.math.ethz.ch
Subject: RE: [R] Overlaying a moving average curve on top of a barplot

>-----Original Message-----
>From: r-help-admin at stat.math.ethz.ch
>[mailto:r-help-admin at stat.math.ethz.ch] On Behalf Of Jos? 
>Santos Alegria
>Sent: Monday, February 03, 2003 5:30 AM
>To: r-help at stat.math.ethz.ch
>Subject: [R] Overlaying a moving average curve on top of a barplot
>
>
>I'm using standard barplot (Windows version 1.6.2 of R) to
>represent a certain weekly metric "v" and I would like to 
>properly overlay on top of it its moving average "mean.8" 
>(window of 8 weeks). I must be doing something wrong since the 
>moving average (using "lines") doesn't overlay properly, i.e.,
>both x-scales do not match!
> 
>...
>barplot(v[8:length(v)], col=7)
>lines(mean.8[1:length(mean.8)],   lty=1, lwd=2, col=2)
>...
> 
>How do I make sure that both graphics are in synch as far as
>the x-scale and y-scales are concerned?
> 
>Thanks,
>
>Jos? A. S. Alegria
The problem that you are having is that you need to get the bar midpoints from
barplot() in order to use those values as the x coordinate values for lines(). 
barplot() returns the bar midpoints as an invisible vector (or matrix where
appropriate).

Modify your code to:

mp <- barplot(v[8:length(v)], col=7)
lines(mp, mean.8[1:length(mean.8)],   lty=1, lwd=2, col=2)

This puts the bar midpoints (x axis values) in mp, which you can then use for
lines().

HTH,

Marc