Displaying 20 results from an estimated 600 matches similar to: "tests for spericity"
2003 Oct 13
1
extracting quoted text from character string
Hello all,
I am trying to solve a problem, and my solution is rather ugly and not very
general. The posts for "[R] help with gsub and grep functions" seemed
relevent
and gave me hope for a more refined and more general solution.
The Problem:
line <- "'this text has spaces' 'thisNot' 3 4 5 6 7 8 9 10"
bad.line <- "'this text has spaces'
2003 Jan 21
1
Modified F-test for heterogeneous error variances
Dear R-help:
Does anyone know of a package in R that will do Welch's modified F-test
for heterogeneous error variances? Are there other statistical techniques
available in R that test the equality of means when homoscedastisity
is violated? 't.test' does this in the pairwise sense when var.equal =
TRUE.
With best wishes and kind regards I am
Sincerely,
Corey A. Moffet
Support
2003 Dec 02
1
Is there a way to use CGIwithR in Windows?
Dear R-Help,
Does anyone know of a way to use CGIwithR in Windows? David Firth the
author of CGIwithR states "It ought to be possible to adapt it for use also
in conjunction with web servers running under Windows NT ... but the author
has no plans for that." I have developed some applications in R that I would
like to make available through a web interface using CGIwithR but at this
2002 Aug 20
1
override ask = TRUE in plot.formula
I am having difficulty with plot.formula.
For example:
-------------------
dat <- data.frame(y = c(1,1,1,2,2,2,3,3,3,4,4,4),
x1 = as.ordered(c(1,1,1,1,1,1,2,2,2,2,2,2)),
x2 = as.ordered(c(1,1,1,2,2,2,1,1,1,2,2,2)))
plot(y ~ x1 + x2, data = dat) # Works fine "interactively" asking:
# "Hit <Return> to see next plot:"
#
2002 Nov 19
5
help reading a variably formatted text file
Dear R-Help,
I have a generated file that looks like the following:
----- Begin file -----
#
# Output File
#
float Version 2002.700000000000
int Numdays 31
int NumOFEs 1
#
# Hillslope-specific variables
#
char HillVarNames[ 3 ]
{Days In Simulation}
{Hillslope: Precipitation (mm)}
2004 Apr 29
1
model.tabels warning refers to wrong function (PR#6839)
Full_Name: Corey A. Moffet
Version: 1.8.1
OS: Windows 2000 and RHL 9
Submission from: (NULL) (199.133.140.156)
The function model.tables.aov and perhaps other model.tables methods refer the
user to use the function se.contrasts when the design is unbalanced. The
function name is se.contrast (singular).
2002 Jan 28
4
Type III Sums of Squares
I am trying to reproduce an analysis done in SAS from which Type III Sums of
squares are used. How can you get Type III sums of squares in an aov similar
to what SAS provides?
With best wishes and kind regards I am
Sincerely,
Corey A. Moffet
Instructor
Department of Range, Wildlife, and Fisheries Management
Mail Stop 2125
Texas Tech University
Lubbock, Texas 79409-2125
(806) 742-2843 Voice
2004 Feb 05
1
What is the correct way of using function C() for factors:
The funciton c() works differently for strings and for factors:
For strings:
> l = c('a', 'b')
> l
[1] "a" "b"
For factors:
> l = c(factor('a'), factor('b'))
> l
[1] 1 1
What should be the right technique for merging factors?
--
Svetlana Eden Biostatistician II School of Medicine
2002 Apr 29
2
Lotos 1-2-3 date to POSIXct
I have some data that was created for import into a Lotus 1-2-3 spreadsheet
and on of the columns is time. The
time is akin to Julian were the value 1 is mapped "01-Jan-00 12:00:00 AM" in
Lotus 1-2-3. Is there a function in an R package that can convert this
numeric vector to a POSIXct vector?
With best wishes and kind regards I am
Sincerely,
Corey A. Moffet
Instructor
Department
2003 Sep 08
3
multiple selection syntax
Hello
This is a very newbie question on R syntax, but I do not find the answer....
I want to make a selection on an interval say choose Xint in the
interval of temperatures 390-399
I tried this syntax
Xint<- X[t>=390 && t< 400]
typing >XintI get the answer numeric(0)
it did not select any object! 'though I verified that there indeed are
occrencies of X in this
2002 Jan 10
4
Test if beta is different from something other than 0
Is there a function/package that will allow you to test the hypothesis beta1
= x in a
simple linear regression, where x is a constant? The AOV tests if beta1 in
different from
0 but what if I want to know if beta1 one is different from 1?
With best wishes and kind regards I am
Sincerely,
Corey A. Moffet
Instructor
Department of Range, Wildlife, and Fisheries Management
Mail Stop 2125
Texas
2003 Oct 13
4
conditional less than
I'm sure this is a total noob question, but half an
hour of searching bore no fruit: How do you select a
subset of a vector by negative value? If I try
> hist(sp$p[sp$r>0.01]) # all is well
> hist(sp$p[sp$r<-0.01]) # this obviously causes
issues
Also, putting -0.01 in parentheses didn't help.
Thanks in advance --
b
2003 Nov 14
6
index of max value ?
Is there a function in R, which would return index of maximum value
in a vector ?
e.g.
> v <- round(10*rnorm(8))
> v
[1] 6 -3 -6 15 7 9 0 -19
> max(v)
[1] 15
??? index.max(v)
??? 4
2002 Apr 17
4
Problem w/ axis and distortion in a plotting function
I have a function for plotting soil texture that I am having a problem with.
The function is:
plot.psd <- function(sand, clay, ...) {
conv.ter <- function(x, y) {
x.con <- 100 - x - y*cos(1/3*pi)
y.con <- y*sin(1/3*pi)
data.frame(x=x.con, y=y.con)
}
plot(conv.ter(sand, clay), xlim = c(0,100), ylim = c(0,100*sin(1/3*pi)),
axes = FALSE, xlab="",
2002 Jul 09
3
Error handling
Hi
I wrote a function implementing an algoritm for simulation of spatial
sampling plans (using geoR).
I'm using a range of parameters to perform several simulation and
sometimes this parameters create function errors wich cause the algoritm
to stop.
How can I avoid this ?
Below there's a small example that I made to study the problem but I was
not able to solve it. I've tried
2002 Sep 27
3
xtable()
Hi,
Does anyone know how to manually configure the number of digits printed
out from xtable()?
For example, I'm exporting a data frame through xtable() into a LaTeX
table, I only have two columns in the data frame so by default I only get
two decimal places. But I'd like at least 5 decimal places.
I had a look at ?xtable() but can't seem to find an example.
Cheers,
Kevin
2003 Oct 20
4
selecting subsets of data from matrix
Probably a stupid question, but I don't seem to be able to find the answer
I'm looking for from any of the R literature. Basically I have a matrix
with several thousand rows and 20 columns(weather stations) of wind
direction data.
I am wanting to extract a matrix which contains data for all columns
conditional on column 20 having a value of _either_ less than 45 or
greater than 315. (ie I
2002 Sep 27
3
Retaining regularly used add-ons
Hi everyone,
How might I go about configuring R to keep
add-on packages loaded from session to session?
Is this undesireable for some reason?
At present, I keep a file called "pckgs.txt" in my
working directory with, e.g.,
library(gnlm)
library(Hmisc)
...
and then type source("add-ons.txt") every time I start
a new session. I suspect there's a more elegant way
to hold
2004 Jul 20
3
regression slope
Hello,
I'm a newcomer to R so please
forgive me if this is a silly question.
It's that I have a linear regression:
fm <- lm (x ~ y)
and I want to test whether the
slope of the regression is significantly
less than 1. How can I do this in R?
I'm also interested in comparing the
slopes of two regressions:
fm1 <- lm (x ~ y)
fm2 <- lm (a ~ b)
and asking if the slope of fm1 is
2004 Sep 15
5
replacing NA's with 0 in a dataframe for specified columns
I know that there must be a cool way of doing this, but I can't think
of it. Let's say I have an dataframe with NA's.
> x <- data.frame(a = c(0,1,2,NA), b = c(0,NA,1,2), c = c(NA, 0, 1, 2))
> x
a b c
1 0 0 NA
2 1 NA 0
3 2 1 1
4 NA 2 2
>
I know it is easy to replace all the NA's with zeroes.
> x[is.na(x)] <- 0
> x
a b c
1 0 0 0
2 1 0 0
3 2 1