Displaying 20 results from an estimated 10000 matches similar to: "data frame as X in linear model lm() ?"
2012 Mar 26
1
assigning vector or matrix sparsely (for use with mclapply)
Dear R wizards---
I have a wrapper on mclapply() that makes it a little easier for me to
do multiprocessing. (Posting this may make life easier for other
googlers.) I pass a data frame, a vector that tells me what rows
should be recomputed, and the function; and I get back a vector or
matrix of answers.
d <- data.frame( id=1:6, val=11:16 )
loc <- c(TRUE,TRUE,FALSE,TRUE,FALSE,TRUE)
2012 Mar 30
4
list assignment syntax?
Dear R wizards: is there a clean way to assign to elements in a list?
what I would like to do, in pseudo R+perl notation is
f <- function(a,b) list(a+b,a-b)
(c,d) <- f(1,2)
and have c be assigned 1+2 and d be assigned 1-2. right now, I use the clunky
x <- f(1,2)
c <- x[[1]]
d <- x[[2]]
rm(x)
which seems awful. is there a nicer syntax?
regards, /iaw
----
Ivo Welch
2008 Aug 25
8
SQL Primer for R
Dear R wizards:
I decided to take the advice in the R data import/export manual and
want to learn how to work with SQL for large data sets. I am trying
SQLite with the DBI and RSQLite database interfaces. Speed is nice.
Alas, I am struggling to find a tutorial that is geared for the kind
of standard operations that I would want in R. Simple things:
* how to determine the number of rows in a
2010 Jan 08
4
fast lm se?
dear R experts---I am using the coef() function to pick off the coefficients
from an lm() object. alas, I also need the standard errors and I need them
fast. I know I can do a "summary()" on the object and pick them off this
way, but this computes other stuff I do not need. Or, I can compute (X'
X)^(-1) s^2 myself. Has someone written a fast se() function?
incidentally, I think
2010 Jun 11
3
lm without error
this is not an important question, but I wonder why lm returns an
error, and whether this can be shut off. it would seem to me that
returning NA's would make more sense in some cases---after all, the
problem is clearly that coefficients cannot be computed.
I know that I can trap the lm.fit() error---although I have always
found this to be quite inconvenient---and this is easy if I have only
2009 Sep 15
2
why is nrow() so slow?
dear R wizards: here is the strange question for the day. It seems to me
that nrow() is very slow. Let me explain what I mean:
ds= data.frame( NA, x=rnorm(10000) ) ## a sample data set
> system.time( { for (i in 1:10000) NA } ) ## doing nothing takes
virtually no time
user system elapsed
0.000 0.000 0.001
## this is something that should take time; we need to add 10,000
2010 Jan 22
2
sorted reshaping?
dear R wizards:? I am wrestling with reshape.? I have a long data set
that I want to convert into a wide data set, in which rows are firms
and columns are years.
> summary(rin)
firm fyear sim1
Min. :1004.00 Min. :1964.0 Min. : -1.00000
1st Qu.:1010.00 1st Qu.:1979.0 1st Qu.: -0.14334
Median :1016.00 Median :1986.0 Median : 0.00116
Mean
2012 May 09
2
big quasi-fixed effects OLS model
dear R experts---now I have a case where I want to estimate very large
regression models with many fixed effects---not just the mean type, but
cross-fixed effects---years, months, locations, firms. Many millions of
observations, a few thousand variables (most of these variables are
interaction fixed effects). could someone please point me to packages, if
any, that would help me estimate such
2007 Apr 20
2
cat() to STDERR
Dear R wizards---I read Brian Ripley's post from 2004 which said that
it was not possible to print to STDERR. Alas, I have more modest
needs. I was wondering if it was possible to just send a string to
STDERR with cat() while in CMD BATCH mode.
Is it not possible to open STDERR in R? (Or does R use STDERR for
itself and redirect it into the output stream?)
This would be on a standard Unix
2010 May 11
3
Revolution R and the R Community?
As an end-user, I wonder about Revolution R. Is the relationship
between Revolution R and the R community at-large a positive one? Do
the former contribute to the development efforts of the latter? Is
there a competitive aspect? is their forum competitive with r-help?
any other thoughts? (most of all, I simply hope that they help some
of the many helpful experts on this forum, who have
2013 Feb 26
1
Light Libraries
Dear R-Help group:
I have been tinkering with how I want my personal standard library
functions to look like. They are not designed to be professional and
heavyweight, but lightweight. There are probably dozens of little bugs,
because I don't know or have not properly taken care of a variety of
internal R code issues. still, I like how this ended up, and there is no
learning curve, so I
2010 Apr 29
1
lm() with non-linear coefficients constraints? --- nls?
dear R experts---quick question. I need to estimate a model that looks like
y = (b*T+d*T^3) + (1-b-3*d*T^2)*x + (3*d*T)*x^2 + (-d)*x^3
I only have three parameters. Is nls() the right tool for the job, or is
there something faster/better?
/iaw
----
Ivo Welch (ivo.welch@brown.edu, ivo.welch@gmail.com)
[[alternative HTML version deleted]]
2006 Apr 03
4
argv[0] --- again
dear R group: I have the probably fairly common problem that I would
like to have one code.R file do different things if it is invoked from
a symbolic link, which should be easy to uncover.
$ ln -s code.R code-0.R
$ ln -s code.R code-1.R
$ R CMD BATCH code-1.R
what needs to be in code-1.R to put code-1.r into a character vector?
help appreciated.
regards, /ivo welch
PS : I read
2011 Jul 24
2
split data frame temporary and work with only part of it?
dear R wizards: I have a large data frame, a million rows, 40
columns. In this data frame, there are some (about 100,000) rows
which I want to recompute (update), while I want to leave others just
as is. this is based on a condition that I need to compute, based on
what is in a few of the columns. what is the right R way to do this?
I could subset out the rows that I want to recompute into a
2010 May 24
1
Fixed Effects Estimations (in Panel Data)
dear readers---I struggled with how to do nice fixed-effects
regressions in large economic samples for a while. Eventually, I
realized that nlme is not really what I needed (too complex), and all
I really wanted is the plm package. so, I thought I would share a
quick example.
################ sample code to show fixed-effects models? in R
# create a sample panel data set with firms and years
2010 Aug 30
4
different interface to by (tapply)?
dear R experts:
has someone written a function that returns the results of by() as a
data frame? ??of course, this can work only if the output of the
function that is an argument to by() is a numerical vector.
presumably, what is now names(byobject) would become a column in the
data frame, and the by object's list elements would become columns.
it's a little bit like flattening the by()
2006 Jun 04
1
text bubble (rectangle)?
Dear R wizards: sorry to bug everyone twice in one day.
I would like to annotate my graph by putting text strings into
rectangle boxes with a little cartoon-like bubble with a lid pointing
to a specific location. I can draw some sort of bubble-with-lid using
the R primitives. (has anyone done something like this already?)
the problem where I am stuck is that the width of the rectangle must
2010 Aug 22
2
on abort error, always show call stack?
Dear R Wizards---is it possible to get R to show its current call
stack (sys.calls()) upon an error abort? I don't use ESS for
execution, and it is often not obvious how to locate how I triggered
an error in an R internal function. Seeing the call stack would make
this easier. (right now, I sprinkle "cat" statements everywhere, just
to locate the line where the error appears.) Of
2004 Jul 07
3
fast NA elimination ?
dear R wizards: an operation I execute often is the deletion of all
observations (in a matrix or data set) that have at least one NA. (I
now need this operation for kde2d, because its internal quantile call
complains; could this be considered a buglet?) usually, my data sets
are small enough for speed not to matter, and there I do not care
whether my method is pretty inefficient (ok, I
2011 Mar 01
3
inefficient ifelse() ?
dear R experts---
t <- 1:30
f <- function(t) { cat("f for", t, "\n"); return(2*t) }
g <- function(t) { cat("g for", t, "\n"); return(3*t) }
s <- ifelse( t%%2==0, g(t), f(t))
shows that the ifelse function actually evaluates both f() and g() for
all values first, and presumably then just picks left or right results
based on t%%2.