R help - Sep 2009 - How to calculate min of a dataset that contains empty column

Hi all,

I have got a dataset like the following:

a  b  c
1      5
2
3      7

I am taking the minimum of each column and use it as the minimum of the
y-axis of my graphs. My scripts (simplified version) are like the following:

f<-array
f[1]=a
f[2]=b
f[3]=c
for i in 1:3
name=f[i]
ymin<-min(dataset$f[i])
plot(x,y,ylim=c(ymin,100))

The script stops at b, because the min function returns inf value. What can
I do to overcome it?

Many thanks,
Chris
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Presumably there is no reason to attempt plotting an empty column, so best
approach is probably to remove the columns that contain no values.  

Try
> f.temp<-f[,-which(apply(f,2,function(x)all(is.na(x))))]
and then run your script for f.temp instead of the original f.  

Also, you may find you have to use
> min(x, na.rm=T) 
instead of just
> min(x)
for any other columns that contain NA values as well as real values.  





Chris Li wrote:
> 
> Hi all,
> 
> I have got a dataset like the following:
> 
> a  b  c
> 1      5
> 2
> 3      7
> 
> I am taking the minimum of each column and use it as the minimum of the
> y-axis of my graphs. My scripts (simplified version) are like the
> following:
> 
> f<-array
> f[1]=a
> f[2]=b
> f[3]=c
> for i in 1:3
> name=f[i]
> ymin<-min(dataset$f[i])
> plot(x,y,ylim=c(ymin,100))
> 
> The script stops at b, because the min function returns inf value. What
> can I do to overcome it?
> 
> Many thanks,
> Chris
> 
-- 
View this message in context:
http://www.nabble.com/How-to-calculate-min-of-a-dataset-that-contains-empty-column-tp25463449p25466916.html
Sent from the R help mailing list archive at Nabble.com.

Let's say your data.frame is called xx

Then try:
apply(xx,2, function(x) {min(na.omit(x))}  )

Does it work ?





On Wed, Sep 16, 2009 at 2:24 AM, Chris Li
<chrisli@austwaterenv.com.au>wrote:
>
> Hi all,
>
> I have got a dataset like the following:
>
> a  b  c
> 1      5
> 2
> 3      7
>
> I am taking the minimum of each column and use it as the minimum of the
> y-axis of my graphs. My scripts (simplified version) are like the
> following:
>
> f<-array
> f[1]=a
> f[2]=b
> f[3]=c
> for i in 1:3
> name=f[i]
> ymin<-min(dataset$f[i])
> plot(x,y,ylim=c(ymin,100))
>
> The script stops at b, because the min function returns inf value. What can
> I do to overcome it?
>
> Many thanks,
> Chris
> --
> View this message in context:
>
http://www.nabble.com/How-to-calculate-min-of-a-dataset-that-contains-empty-column-tp25463449p25463449.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


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