order and rm() - R-help | R Mailing Lists

Peter Wolf · 2002-11-19T08:08:08Z

Jess Balint wrote: >Hello all. I have two small questions in one post, for the sake of brevity. > >1. I have some objects that I want to delete. I have the line: >rm (c (channelheader, paste ("channel", 1:3, sep=""))) > >I have tried a few variations, including list=, but cannot figure it out. In >SAS, I can use a ':' as a wildcard. Is there any equivalent in R? > >2. Is there any possible was to order data by the second to last character? > >TIA. 1. # to remove all objects whose names starts

Peter Wolf

Tue, Nov 19, 2002 12:08 AM #

Jess Balint wrote:

brevity.

out. In

character?

1. # to remove all objects whose names starts by "xyz" followed by a
digit use:

See: ->  help(ls) -> use of argument "pattern" -> regular expressions
Take care: wild characters / regular expressions are dangerous in
removal processes

2. # to sort a vector of strings by the last and the last but one
characters

Peter Wolf

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Andrew Beckerman

Wed, Nov 20, 2002 6:17 AM #

R1.61, WinNT

Dear listers - I am trying to implement the SPLUS example for boostrapping 
coefficients from a linear model -

boot(data.frame, coef(eval(model$call)))

I get errors saying that my statistic is not defined and that the 
replicates are not defined.  Changing this to -

boot(recTTM, statisitic=coef(eval(mod$call)),R=999)

still gives the error about the statistic.  Clearly I do not understand 
what the statisitic is and how to make the coefficients a function as in 
the examples in the help... can someone guide me on syntax?

cheers
andrew
----------------------------------------------------------
Dr. Andrew Beckerman
Institute of Biological Science
University of Stirling
Stirling FK9 4LA
+44 (0)1786 then wk-467808 fx-464994
(APB is not responsible for anything below this)

The University of Stirling is a university established in Scotland by
charter at Stirling, FK9 4LA.  Privileged/Confidential Information may
be contained in this message.  If you are not the addressee indicated
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Vaidotas Zemlys

Wed, Nov 20, 2002 7:19 AM #

Hi,

Try ?boot. There are some examples and good explanation of arguments
boot function needs. 

As for a simple explanation, in your case (with default parameters)
statistic must be a function of two arguments, first argument the data,
and second the vector of indices which define the bootstrap sample.  For
example let us say that our data is my.data, and we want to bootstrap
linear regression coefficients, where dependent variable is the first
column of my.data, and independent variables are the rest columns of
my.data. Then the call to boot function would be

boot(my.data,statistic=boot.fun,R=999),

where

boot.fun <-
function(data,ind) {
    coef(lsfit(data[ind,-1],data[ind,1],intercept=TRUE))
    #Note: we could use the lm, but if we only need the regression
    #coefficients, lsfit is faster
}

Hope it helps

Vaidotas Zemlys

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John Fox

Wed, Nov 20, 2002 7:26 AM #

Dear Andrew,

My R and S-PLUS Companion has an on-line appendix on bootstrapping 
regression models that might be of help. You can find it (and other 
appendices) at 
<http://www.socsci.mcmaster.ca/jfox/Books/Companion/appendix.html>.

I hope that this answers your questions.
  John

At 02:17 PM 11/20/2002 +0000, Andrew Beckerman wrote:

R1.61, WinNT

Dear listers - I am trying to implement the SPLUS example for boostrapping 
coefficients from a linear model -

boot(data.frame, coef(eval(model$call)))

I get errors saying that my statistic is not defined and that the 
replicates are not defined.  Changing this to -

boot(recTTM, statisitic=coef(eval(mod$call)),R=999)

still gives the error about the statistic.  Clearly I do not understand 
what the statisitic is and how to make the coefficients a function as in 
the examples in the help... can someone guide me on syntax?

cheers
andrew
----------------------------------------------------------
Dr. Andrew Beckerman
Institute of Biological Science
University of Stirling
Stirling FK9 4LA
+44 (0)1786 then wk-467808 fx-464994
(APB is not responsible for anything below this)

--
The University of Stirling is a university established in Scotland by
charter at Stirling, FK9 4LA.  Privileged/Confidential Information may
be contained in this message.  If you are not the addressee indicated
in this message (or responsible for delivery of the message to such
person), you may not disclose, copy or deliver this message to anyone
and any action taken or omitted to be taken in reliance on it, is
prohibited and may be unlawful.  In such case, you should destroy this
message and kindly notify the sender by reply email.  Please advise
immediately if you or your employer do not consent to Internet email
for messages of this kind.  Opinions, conclusions and other
information in this message that do not relate to the official
business of the University of Stirling shall be understood as neither
given nor endorsed by it.

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____________________________
John Fox
Department of Sociology
McMaster University
email: jfox at mcmaster.ca
web: http://www.socsci.mcmaster.ca/jfox
____________________________

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Brian Ripley

Wed, Nov 20, 2002 7:53 AM #

Let's see?  boot is not part of R, but there is one in package boot.
However, S-PLUS does not come with boot at all.  I think you are
trying to use an example from the wrong package, perhaps for a
function called `bootstrap'?

The boot package and the book it supports (and MASS and the book it
supports) have plenty of examples of this, so why not follow them?
You do need to be aware of the difference beween bootstrapping
cases and bootstrapping residuals.  There's an example of the latter in
?boot.

On Wed, 20 Nov 2002, Andrew Beckerman wrote:

R1.61, WinNT

Dear listers - I am trying to implement the SPLUS example for boostrapping
coefficients from a linear model -

boot(data.frame, coef(eval(model$call)))

I get errors saying that my statistic is not defined and that the
replicates are not defined.  Changing this to -

boot(recTTM, statisitic=coef(eval(mod$call)),R=999)

still gives the error about the statistic.  Clearly I do not understand
what the statisitic is and how to make the coefficients a function as in
the examples in the help... can someone guide me on syntax?

cheers
andrew
----------------------------------------------------------
Dr. Andrew Beckerman
Institute of Biological Science
University of Stirling
Stirling FK9 4LA
+44 (0)1786 then wk-467808 fx-464994
(APB is not responsible for anything below this)

--
The University of Stirling is a university established in Scotland by
charter at Stirling, FK9 4LA.  Privileged/Confidential Information may
be contained in this message.  If you are not the addressee indicated
in this message (or responsible for delivery of the message to such
person), you may not disclose, copy or deliver this message to anyone
and any action taken or omitted to be taken in reliance on it, is
prohibited and may be unlawful.  In such case, you should destroy this
message and kindly notify the sender by reply email.  Please advise
immediately if you or your employer do not consent to Internet email
for messages of this kind.  Opinions, conclusions and other
information in this message that do not relate to the official
business of the University of Stirling shall be understood as neither
given nor endorsed by it.

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Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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Roger D. Peng

Wed, Nov 20, 2002 10:23 AM #

Your error is based on a misunderstanding of what the 'statistic' should
look like for the boot() function.  The statistic needs to take the data
as an argument and a vector of indices -- it is the indicies which get
resampled.  

I wrote a very simple package for bootstrapping in a few classical
situations, including linear models.  You can resample rows and residuals.
It's available at http://department.stat.ucla.edu/~rpeng/uclaboot.  The
interface is (in my opinion, of course!) a little easier to use than the
boot library.  

-roger
_______________________________
UCLA Department of Statistics
rpeng at stat.ucla.edu
http://www.stat.ucla.edu/~rpeng

On Wed, 20 Nov 2002, Andrew Beckerman wrote:

R1.61, WinNT

Dear listers - I am trying to implement the SPLUS example for boostrapping 
coefficients from a linear model -

boot(data.frame, coef(eval(model$call)))

I get errors saying that my statistic is not defined and that the 
replicates are not defined.  Changing this to -

boot(recTTM, statisitic=coef(eval(mod$call)),R=999)

still gives the error about the statistic.  Clearly I do not understand 
what the statisitic is and how to make the coefficients a function as in 
the examples in the help... can someone guide me on syntax?

cheers
andrew
----------------------------------------------------------
Dr. Andrew Beckerman
Institute of Biological Science
University of Stirling
Stirling FK9 4LA
+44 (0)1786 then wk-467808 fx-464994
(APB is not responsible for anything below this)

-- 
The University of Stirling is a university established in Scotland by
charter at Stirling, FK9 4LA.  Privileged/Confidential Information may
be contained in this message.  If you are not the addressee indicated
in this message (or responsible for delivery of the message to such
person), you may not disclose, copy or deliver this message to anyone
and any action taken or omitted to be taken in reliance on it, is
prohibited and may be unlawful.  In such case, you should destroy this
message and kindly notify the sender by reply email.  Please advise
immediately if you or your employer do not consent to Internet email
for messages of this kind.  Opinions, conclusions and other
information in this message that do not relate to the official
business of the University of Stirling shall be understood as neither
given nor endorsed by it.

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