R help - Mar 2003 - log axis assignment

Hi again,
another problem:

This (below) isn't working and as far as I can see it damn well should. What
I'm trying to acomplish is to run several data sets through the same 
graphing procedure, but for the pH data use a log y axis. using this code 
all graphs are drawn with a linear axis. Surely I should be able to set the 
ylog option to T using another object (logaxis).

for (n in colnames(raw))
{
if(n=="pH"){logaxis<-"T"} else
{logaxis<-"F"}
plot(full.age,raw[,n],type="n",ylog=logaxis)
...
}

Any ideas what I'm doing wrong? I assume its something to do with the ylog 
(and xlog) options being read-only but I'm not sure what that means.
J

>-----Original Message-----
>From: r-help-admin at stat.math.ethz.ch 
>[mailto:r-help-admin at stat.math.ethz.ch] On Behalf Of Jeremy Z Butler
>Sent: Monday, March 03, 2003 10:57 PM
>To: r-help at stat.math.ethz.ch
>Subject: [R] log axis assignment
>
>
>Hi again,
>another problem:
>
>This (below) isn't working and as far as I can see it damn 
>well should. What 
>I'm trying to acomplish is to run several data sets through the same 
>graphing procedure, but for the pH data use a log y axis. 
>using this code 
>all graphs are drawn with a linear axis. Surely I should be 
>able to set the 
>ylog option to T using another object (logaxis).
>
>for (n in colnames(raw))
>{
>if(n=="pH"){logaxis<-"T"} else
{logaxis<-"F"}
>plot(full.age,raw[,n],type="n",ylog=logaxis)
>...
>}
>
>Any ideas what I'm doing wrong? I assume its something to do 
>with the ylog 
>(and xlog) options being read-only but I'm not sure what that means.
J


You cannot set the log scaling in the fashion in which you are trying
by setting par(ylog) as an argument to plot().  Presumably you are
getting the following error message:

"parameter "ylog" couldn't be set in high-level plot()
function"


Try this instead using the proper 'log' argument to plot:

for (n in colnames(raw))
{
  if(n == "pH")
    plot(full.age, raw[,n], type = "n",  log = "y")
  else
    plot(full.age, raw[,n], type = "n")
...
}

See ?plot.default for more information.

Also, "T" and "F" as quoted characters are not the same as
TRUE and
FALSE as logical boolean values.

HTH,

Marc Schwartz

From: Jeremy Z Butler [mailto:jerrytheshrub at
hotmail.com]
> Surely I should be able to set the 
> ylog option to T using another object (logaxis).
>
>for (n in colnames(raw))
>{
>if(n=="pH"){logaxis<-"T"} else
{logaxis<-"F"}
>plot(full.age,raw[,n],type="n",ylog=logaxis)
>...
>}
What (probably) will work is:

if(n=="pH"){logaxis<-"Y"} else {logaxis<-""}
plot(full.age,raw[,n],type="n",log=logaxis)

The plot-argument log takes which axis that shuld be logaritmic. 


Morten