thr3ads.net - R help - [R] if/else help [Sep 2016]

If this information is useful, please help other people find it:
Share via:

Crombie, Burnette N

2016-Sep-20 19:31 UTC

[R] if/else help

If a data.frame (r4) does not exist in my R environment, I would like to create
it before I move on to the next step in my script. How do I make that happen? 
Here is what I want to do from a code perspective:

if (exists(r4))
{
is.data.frame(get(r4))
}
else
{
a <- 0, b <- 0, c <- 0, d <- "x", r4 <-
data.frame(cbind(a,b,c,d))
}

Thanks for your help,
B

	[[alternative HTML version deleted]]

Jeff Newmiller

2016-Sep-21 06:57 UTC

head link

[R] if/else help

Get rid of the commas? Get rid of the get() function call? Get rid of the
cbind() function call?  Post using plain text format so the HTML doesn't
screw up code? Read the Posting Guide? All of these ideas have merit IMHO...
-- 
Sent from my phone. Please excuse my brevity.

On September 20, 2016 12:31:47 PM PDT, "Crombie, Burnette N"
<bcrombie at utk.edu> wrote:>If a data.frame (r4) does not exist in my R environment, I would like
>to create it before I move on to the next step in my script. How do I
>make that happen?  Here is what I want to do from a code perspective:
>
>if (exists(r4))
>{
>is.data.frame(get(r4))
>}
>else
>{
>a <- 0, b <- 0, c <- 0, d <- "x", r4 <-
data.frame(cbind(a,b,c,d))
>}
>
>Thanks for your help,
>B
>
>	[[alternative HTML version deleted]]
>
>______________________________________________
>R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>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.

David Winsemius

2016-Sep-21 06:58 UTC

head link

[R] if/else help

> On Sep 20, 2016, at 12:31 PM, Crombie, Burnette N <bcrombie at
utk.edu> wrote:
> 
> If a data.frame (r4) does not exist in my R environment, I would like to
create it before I move on to the next step in my script. How do I make that
happen?  Here is what I want to do from a code perspective:
> 
> if (exists(r4))
> {
> is.data.frame(get(r4))
> }
> else
> {
> a <- 0, b <- 0, c <- 0, d <- "x", r4 <-
data.frame(cbind(a,b,c,d))
> }
> 
> Thanks for your help,
> B
> 
> 	[[alternative HTML version deleted]]
Please, please, please, do not encourage people to use the construction:

data.frame(cbind(....

...and learn to distrust whatever misguided example you learned it from. (Yes, I
know there is one in the help pages but that is an exception to the rule.)

There is no reason to use it. It would be much clearer to do this:

r4 <- data.frame(a = 0, b = 0, c = 0, d = "x")    # only one column
is factor-class.

If you did it your way you would have gotten four columns of factors, (first
cbind() creates a character matrix, and then data.frame() creates factors)  ...
which does not appear to be what you expected.

And ... as always has been the case on Rhelp, ... learn to post in plain text.
> 
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
David Winsemius
Alameda, CA, USA

William Dunlap

2016-Sep-21 14:47 UTC

head link

[R] if/else help

If you write your code as functions you can avoid the nasty
'if(exists("x"))x<-...' business this by writing default
values for
arguments to your function.   They will be computed only when
they are used.  E.g.,

analyzeData <- function(a=0, b=0, c=0, d="x", r4 = data.frame(a, b,
c, d)) {
    summary(r4)
}
> analyzeData(c=101:102)       a           b           c         d
 Min.   :0   Min.   :0   Min.   :101.0   x:2
 1st Qu.:0   1st Qu.:0   1st Qu.:101.2
 Median :0   Median :0   Median :101.5
 Mean   :0   Mean   :0   Mean   :101.5
 3rd Qu.:0   3rd Qu.:0   3rd Qu.:101.8
 Max.   :0   Max.   :0   Max.   :102.0>
analyzeData(r4=data.frame(a=10:11,b=20:21,c=30:31,d=c("x","y")))       a               b               c         d
 Min.   :10.00   Min.   :20.00   Min.   :30.00   x:1
 1st Qu.:10.25   1st Qu.:20.25   1st Qu.:30.25   y:1
 Median :10.50   Median :20.50   Median :30.50
 Mean   :10.50   Mean   :20.50   Mean   :30.50
 3rd Qu.:10.75   3rd Qu.:20.75   3rd Qu.:30.75
 Max.   :11.00   Max.   :21.00   Max.   :31.00



Bill Dunlap
TIBCO Software
wdunlap tibco.com

On Tue, Sep 20, 2016 at 12:31 PM, Crombie, Burnette N <bcrombie at
utk.edu>
wrote:
> If a data.frame (r4) does not exist in my R environment, I would like to
> create it before I move on to the next step in my script. How do I make
> that happen?  Here is what I want to do from a code perspective:
>
> if (exists(r4))
> {
> is.data.frame(get(r4))
> }
> else
> {
> a <- 0, b <- 0, c <- 0, d <- "x", r4 <-
data.frame(cbind(a,b,c,d))
> }
>
> Thanks for your help,
> B
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>
	[[alternative HTML version deleted]]

Crombie, Burnette N

2016-Sep-21 14:59 UTC

head link

[R] if/else help

Thanks very much for your detailed reply to my post.  Very helpful/useful
tool(s) you?ve provide me.  Best wishes, B.

From: William Dunlap [mailto:wdunlap at tibco.com]
Sent: Wednesday, September 21, 2016 10:48 AM
To: Crombie, Burnette N <bcrombie at utk.edu>
Cc: r-help at r-project.org
Subject: Re: [R] if/else help

If you write your code as functions you can avoid the nasty
'if(exists("x"))x<-...' business this by writing default
values for
arguments to your function.   They will be computed only when
they are used.  E.g.,
analyzeData <- function(a=0, b=0, c=0, d="x", r4 = data.frame(a, b,
c, d)) {
    summary(r4)
}> analyzeData(c=101:102)       a           b           c         d
 Min.   :0   Min.   :0   Min.   :101.0   x:2
 1st Qu.:0   1st Qu.:0   1st Qu.:101.2
 Median :0   Median :0   Median :101.5
 Mean   :0   Mean   :0   Mean   :101.5
 3rd Qu.:0   3rd Qu.:0   3rd Qu.:101.8
 Max.   :0   Max.   :0   Max.   :102.0>
analyzeData(r4=data.frame(a=10:11,b=20:21,c=30:31,d=c("x","y")))       a               b               c         d
 Min.   :10.00   Min.   :20.00   Min.   :30.00   x:1
 1st Qu.:10.25   1st Qu.:20.25   1st Qu.:30.25   y:1
 Median :10.50   Median :20.50   Median :30.50
 Mean   :10.50   Mean   :20.50   Mean   :30.50
 3rd Qu.:10.75   3rd Qu.:20.75   3rd Qu.:30.75
 Max.   :11.00   Max.   :21.00   Max.   :31.00

Bill Dunlap
TIBCO Software
wdunlap tibco.com<http://tibco.com>

On Tue, Sep 20, 2016 at 12:31 PM, Crombie, Burnette N <bcrombie at
utk.edu<mailto:bcrombie at utk.edu>> wrote:
If a data.frame (r4) does not exist in my R environment, I would like to create
it before I move on to the next step in my script. How do I make that happen? 
Here is what I want to do from a code perspective:

if (exists(r4))
{
is.data.frame(get(r4))
}
else
{
a <- 0, b <- 0, c <- 0, d <- "x", r4 <-
data.frame(cbind(a,b,c,d))
}

Thanks for your help,
B

        [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org<mailto:R-help at r-project.org> mailing list -- To
UNSUBSCRIBE and more, see
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.

	[[alternative HTML version deleted]]

R help - Sep 2016 - if/else help

[R] if/else help

[R] if/else help

[R] if/else help

[R] if/else help

[R] if/else help