R help - May 2011 - SAPPLY function XXXX

Hello everyone,

I am attempting to write a function to count the number of non-missing
values of each column in a data frame using the sapply function. I have the
following code which is receiving the error message below.

> n.valid<-sapply(data1,sum(!is.na))
Error in !is.na : invalid argument type

Ultimately, I would like for this to be 1 conponent in a larger function
that will produce PROC CONTENTS style output. Something like...

data1.contents<-data.frame(Variable=names(data1),
 Class=sapply(data1,class),
 n.valid=sapply(data1,sum(!is.na)),
 n.miss=sapply(data1,sum(is.na)))
data1.contents

Any suggestions/assistance are appreciated.

Thank you,

Daniel

	[[alternative HTML version deleted]]

Dan,

> I am attempting to write a function to count the number of non-missing
> values of each column in a data frame using the sapply function. I have the
> following code which is receiving the error message below.
> 
> 
>> n.valid<-sapply(data1,sum(!is.na))
> Error in !is.na : invalid argument type
That's the FUN argument to sapply, which expects a function.  is.na is 
indeed a function, but !is.na is not a function:

 > !is.na
Error in !is.na : invalid argument type

You need to write your own function to do what you want. Luckily this is 
easy. Let's write one to count the number of missing values in a vector.

countNAs <- function(x) {
    sum(!is.na(x))
}

Now you have a function that does what you want, so you can use sapply 
with it.

sapply(data1, countNAs)

You could also do an anonymous (unnamed) function within sapply to the 
same effect.

sapply(data1, function(x) sum(!is.na(x)))

NB: none of this is tested!

--Erik

> 
> Ultimately, I would like for this to be 1 conponent in a larger function
> that will produce PROC CONTENTS style output. Something like...
> 
> data1.contents<-data.frame(Variable=names(data1),
>  Class=sapply(data1,class),
>  n.valid=sapply(data1,sum(!is.na)),
>  n.miss=sapply(data1,sum(is.na)))
> data1.contents
> 
> Any suggestions/assistance are appreciated.
> 
> Thank you,
> 
> Daniel
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at 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.

> Ultimately, I would like for this to be 1 conponent in a larger function
> that will produce PROC CONTENTS style output. Something like...
> 
> data1.contents<-data.frame(Variable=names(data1),
>  Class=sapply(data1,class),
>  n.valid=sapply(data1,sum(!is.na)),
>  n.miss=sapply(data1,sum(is.na)))
> data1.contents
Also meant to mention to see ?describe in the Hmisc package:

E.g.,

 > describe(c(NA, 1:10))

There is also a useful method for data.frame objects.

--Erik

Hi

r-help-bounces at r-project.org napsal dne 04.05.2011 22:26:59:
> Erik Iverson <eriki at ccbr.umn.edu> 
> Odeslal: r-help-bounces at r-project.org
> 
> 04.05.2011 22:26
> 
> Komu
> 
> Dan Abner <dan.abner99 at gmail.com>
> 
> 
> > Ultimately, I would like for this to be 1 conponent in a larger 
function
> > that will produce PROC CONTENTS style output. Something like...
> > 
> > data1.contents<-data.frame(Variable=names(data1),
> >  Class=sapply(data1,class),
> >  n.valid=sapply(data1,sum(!is.na)),
> >  n.miss=sapply(data1,sum(is.na)))
> > data1.contents
> 
> Also meant to mention to see ?describe in the Hmisc package:
> 
> E.g.,
> 
>  > describe(c(NA, 1:10))
> 
> There is also a useful method for data.frame objects.
colSums(is.na(data1))
colSums(!is.na(data1))

may also show number of missing and nonmissing values in data frame.

Regards
Petr
> 
> --Erik
> 
> ______________________________________________
> R-help at 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.