R help - Dec 2004 - If it's not a data.frame, matrix or vector, what is it?

Hi

Forgive my ignorance.  I am selecting a column of a data.frame using the
column name, and I want to know what the resulting column "is".  My
data
frame is called "submin" and the column name is held in a variable
called "display.gname" Eg:
> is.data.frame(submin)
[1] TRUE
> is.data.frame(submin[,display.gname])
[1] FALSE
> is.matrix(submin[,display.gname])
[1] FALSE
> is.vector(submin[,display.gname])
[1] FALSE
> length(submin[,display.gname])
[1] 4622

So if it's not a data.frame, a matrix or a vector, what is "it"?

Thanks (and sorry if this is in the FAQ)

Mick

What does str(submin$display.gname) say?

Andy
> From: michael watson (IAH-C)
> 
> Hi
> 
> Forgive my ignorance.  I am selecting a column of a 
> data.frame using the
> column name, and I want to know what the resulting column 
> "is".  My data
> frame is called "submin" and the column name is held in a
variable
> called "display.gname" Eg:
> 
> > is.data.frame(submin)
> [1] TRUE
> > is.data.frame(submin[,display.gname])
> [1] FALSE
> > is.matrix(submin[,display.gname])
> [1] FALSE
> > is.vector(submin[,display.gname])
> [1] FALSE
> > length(submin[,display.gname])
> [1] 4622
> 
> So if it's not a data.frame, a matrix or a vector, what is
"it"?
> 
> Thanks (and sorry if this is in the FAQ)
> 
> Mick
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! 
> http://www.R-project.org/posting-guide.html
> 
>

OK I'm definitely being a bit ignorant (so please accept my apologies)
of R and it's internal data storage.

When I created the data.frame, I did use I() with this column - the
original data being a vector created simply with "vector()".  It's
clear
now that I didn't realise exactly what this was doing (all I wanted was
for it to NOT be converted to a factor).  
> str(submin[,display.gname])
Class 'AsIs'  chr [1:4622] "" "" ""
"" ...
> is.array(submin[,display.gname])
[1] FALSE
> class(submin[,display.gname])
[1] "AsIs"

But I am still confused; I program mainly in perl and java, and this
"thing" - it's not a vector, an array, a matrix or a data.frame -
so
what is "it"? :-S

Thanks 

Mick


-----Original Message-----
From: Liaw, Andy [mailto:andy_liaw at merck.com] 
Sent: 17 December 2004 15:55
To: michael watson (IAH-C); r-help at stat.math.ethz.ch
Subject: RE: [R] If it's not a data.frame, matrix or vector, what is it?


What does str(submin$display.gname) say?

Andy
> From: michael watson (IAH-C)
> 
> Hi
> 
> Forgive my ignorance.  I am selecting a column of a
> data.frame using the
> column name, and I want to know what the resulting column 
> "is".  My data
> frame is called "submin" and the column name is held in a
variable
> called "display.gname" Eg:
> 
> > is.data.frame(submin)
> [1] TRUE
> > is.data.frame(submin[,display.gname])
> [1] FALSE
> > is.matrix(submin[,display.gname])
> [1] FALSE
> > is.vector(submin[,display.gname])
> [1] FALSE
> > length(submin[,display.gname])
> [1] 4622
> 
> So if it's not a data.frame, a matrix or a vector, what is
"it"?
> 
> Thanks (and sorry if this is in the FAQ)
> 
> Mick
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list 
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
> 
> 

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It may be educational to read the help pages of functions that you're using,
namely ?I (or even ?AsIs) and ?as.vector.  ?I says it simply prepend
"AsIs"
to the class attribute of the object.  ?as.vector says it returns FALSE if
the object has any attributes except names (which it does in this case: the
class).  Note that str() does tell you that it's `chr', or character. 
You
can unclass() it to see what it actually is.

HTH,
Andy

> From: michael watson (IAH-C) 
> 
> 
> OK I'm definitely being a bit ignorant (so please accept my apologies)
> of R and it's internal data storage.
> 
> When I created the data.frame, I did use I() with this column - the
> original data being a vector created simply with "vector()".  
> It's clear
> now that I didn't realise exactly what this was doing (all I 
> wanted was
> for it to NOT be converted to a factor).  
> 
> > str(submin[,display.gname])
> Class 'AsIs'  chr [1:4622] "" "" ""
"" ...
> > is.array(submin[,display.gname])
> [1] FALSE
> > class(submin[,display.gname])
> [1] "AsIs"
> 
> But I am still confused; I program mainly in perl and java, and this
> "thing" - it's not a vector, an array, a matrix or a
data.frame - so
> what is "it"? :-S
> 
> Thanks 
> 
> Mick
> 
> 
> -----Original Message-----
> From: Liaw, Andy [mailto:andy_liaw at merck.com] 
> Sent: 17 December 2004 15:55
> To: michael watson (IAH-C); r-help at stat.math.ethz.ch
> Subject: RE: [R] If it's not a data.frame, matrix or vector, 
> what is it?
> 
> 
> What does str(submin$display.gname) say?
> 
> Andy
> 
> > From: michael watson (IAH-C)
> > 
> > Hi
> > 
> > Forgive my ignorance.  I am selecting a column of a
> > data.frame using the
> > column name, and I want to know what the resulting column 
> > "is".  My data
> > frame is called "submin" and the column name is held in a
variable
> > called "display.gname" Eg:
> > 
> > > is.data.frame(submin)
> > [1] TRUE
> > > is.data.frame(submin[,display.gname])
> > [1] FALSE
> > > is.matrix(submin[,display.gname])
> > [1] FALSE
> > > is.vector(submin[,display.gname])
> > [1] FALSE
> > > length(submin[,display.gname])
> > [1] 4622
> > 
> > So if it's not a data.frame, a matrix or a vector, what is
"it"?
> > 
> > Thanks (and sorry if this is in the FAQ)
> > 
> > Mick
> > 
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list 
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide!
> > http://www.R-project.org/posting-guide.html
> > 
> > 
> 
> 
> --------------------------------------------------------------
> ----------
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> Notice:  This e-mail message, together with any attachment...{{dropped}}