Displaying 20 results from an estimated 700 matches similar to: "subset a matrix"
2006 Apr 13
2
a question on subset a dataset
Dear R-users,
I generate a dataset "d", and want to get a subset from it.
**
*z<-rnorm(9)
coords<-cbind(x=c(1,1,1,2,2,2,3,3,3),y=c(1,2,3,1,2,3,1,2,3))
d<-SpatialPointsDataFrame(coords, data.frame (z=z[1:9]))*
The result*/dataset* is
coordinates z
1 (1, 1) 1.41173570
2 (1, 2) 0.18546503
3 (1, 3) -0.04369144
4 (2, 1) -0.21591338
5 (2, 2)
2006 Mar 22
1
How to join "specific Special Interest Group (=: SIG) mailing lists"
there are several specific Special Interest Group (=: SIG) mailing
lists,and i'm interested in the"R-sig-Geo :R Special Interest Group on
using Geographical data and Mapping ",but can't find how to join it,
could anybody tell me how to do that? thank u very much!
--
Kind Regards,Zhi Jie,Zhang ,PHDDepartment of EpidemiologySchool of
Public HealthFudan
2006 Jun 08
1
how to analyze the following data?--anxious for the result
Dear friends,
I have a dataset: response var--y, class var-group, and the third variable-x.
I want to test whether there is statistical significance bewteen
group for y with the controlled x. First, i want to use analysis of
covariance in SAS, but i found that y isn't noramal and can't become
normal through transformation.
Under that condition, what should i do using R / SAS?
Any
2006 Mar 24
1
who can tell me the reason why it is different on calculating Moran's I using ARCGIS, Geoda and R?
The attachment is my dataset:
1.ccc.shp (the original data)
2.ccc.gwt, which is computed by Geoda;
Introduction to the variables in my data:
ID: key variable;
N_LATITUDE: latitude measured by GPS;
E_LONGITUD: longitude measured by GPS;
LIVES: attribute data
I get the different result of Moran's between ARCGIS and Geoda, R, why?
ARCGIS:spatial statistics tools:spatial
2008 Sep 23
3
Generating series of distributions with the same skewness and different kurtosis or with same kurtosis and different skewness?
Dear R users,
I hope to explain the concepts of skewness and kurtosis by generating
series of distributions with same skewness and different kurtosis or with
same kurtosis and different skewness, but it seems that i cannot find the
right functions.
I have searched the mailing list, but no answers were found.
Is it possible to do that in R? Which function could be used?
Thanks a lot.
--
2007 Aug 17
3
Is there any good tools to facilitate us to create R functions?
Dear R users,
We have some programs for the specific task in our research, but they were
very commonly used. We want to make some functions for them, anybody can
recommend any good tools to facilitate us to create R functions even without
going deep into the theories of R functions ?
Any suggestions or help are greatly appreciated.
--
With Kind Regards,
oooO:::::::::
(..):::::::::
2007 Sep 13
2
handle dates in R?
Dear Rusers,
I have some data in .csv file like "2004-8-1" and "2004-10-1", and i need
to convert them into days from the origin (January 1, 1960).
I have tried the function date.mmddyyyy(), but cannot get it. Anybody can
show me how to handle the date data?
Thanks very much!
My dataset like:
time
2004-8-1
2004-10-1
2001-9-1
2002-9-1
--
With Kind Regards,
2007 Oct 02
2
How to add legend for image()?
Dear friends,
The following is an example to explain my question. I want to get a
legend which will show the z-values according to different colors in image()
function.
x<-sort(runif(10)) #x-coordinates
y<-sort(runif(10)) #y-coordinates
z<-matrix(runif(100),nrow=10) #attributes values
image(x,y,z,col=gray((6:3)/6))
# legend(x,y,legend=z,col=gray((6:3)/6)) #error. the colors should
2008 Jan 01
3
Specify a correct formula in R for Piecewise Linear Functions?
Dear all,
I have two variables, y and x. It seems that the relationship between them
is Piecewise Linear Functions. The cutpoint is 20. That is, when x<20, there
is a linear relationship between y and x; while x>=20, there is another
different linear relationship between them.
How can i specify their relationships in R correctly?
# glm(y~I(x<20)+I(x>=20),family = binomial, data =
2007 Oct 12
3
Anybody has ever met the problem to add a legend to a figure generated by image()?
Dear friends,
Anybody has ever met the problem to add a legend to a figure generated by
image()? I have three variables,x,y and z.
x and y are the coordinates, and z is the third values. we can use image(x,
y, z,...) to generate a figure according to the z-values, but the problem is
the figure legend. How can the legend be added to a figure generated
by image()? Note that filled.contour() can
2006 Nov 19
2
questions on adding reference line?
Dear Ruser,
I use abline() function to add the reference line successfully, but i
can't display the values corresponding to the reference line on the x/y
axis, anybody knows how to display it?
*My simulated programs:*
y<-rnorm(50)
plot(x,y)
abline(v=0.5) *#my question is how to display x=0.5 in the x axis?*
Thanks in advance.
--
With Kind Regards,
oooO:::::::::
(..):::::::::
2006 Jul 02
2
how to recode in my dataset?
Dear Rusers,
My question is about "recode variables". First, i'd like to say
something about the idea of recoding:
My dataset have three variables:type,soiltem and airtem,which means
grass type, soil temperature and air temperature. As we all known, the
change of air temperature is greater than soil temperature,so the
values in those two different temperaturemay represent different
2006 Jun 20
3
how to put the results of loop into a dataframe
Dear friends,
suppose i want to do the following caulation for 100 times, how to put the
results of x , y and z into the same dataframe/dataset?
x<-runif(1)
y<-x+1
z<-x+y
thanks in advance!
--
Kind Regards,
Zhi Jie,Zhang ,PHD
Department of Epidemiology
School of Public Health
Fudan University
Tel:86-21-54237149
[[alternative HTML version deleted]]
2006 Jul 13
3
set the bahavior that R deal with missing values?
Dear Rusers,
The default behavior in R when performing a regression model with missing
values is to exclude any case that contains a
missing value? How could i set the bahavior that R deal with missing values?
e.g.:
exclude cases listwise
exclude cases pairwise
replace with mean
Thanks very much!
--
Kind Regards,
Zhi Jie,Zhang ,PHD
Department of Epidemiology
School of Public Health
Fudan
2007 Dec 31
2
help on ROC analysis
Dear all,
Some functions like 'ROC(Epi)' can be used to perform ROC analyssi, but it
needs us to specify the fitting model in the argument. Now i have got the
predicted p-values (0,1) for the 0/1 response variable using some other
approach, see the following example dataset:
id mark predict.pvalue
1 1 0.927
2 0 0.928
3 1 0.928
..................
2006 Oct 12
2
how to get the variance-covariance matrix/information of alpha and beta after fitting a GLMs?
Dear friends,
After fitting a generalized linear models ,i hope to get the variance of
alpha,variance of beta and their covariance, that is , the
variance-covariance matrix/information of alpha and beta , suppose *B* is
the object of GLMs, i use attributes(B) to look for the options ,but can't
find it, anybody knows how to get it?
> attributes(B)
$names
[1] "coefficients"
2007 Sep 17
2
What's the corresponding function in R for lo() function in S-PLUS?
Dear friends,
In S-PLUS, we can use the following argument, but not in R.
mode12 <- gam(score1 ~ lo(latitude) + lo(longitude))
I searched the help in S-PLUS, it says lo() Allows the user to specify a
Loess fit in a GAM formula, but i didn't find the correponding function in
R.
Anybody knows how to do the similar task in R?
Thanks very much.
--
With Kind Regards,
oooO:::::::::
2006 Jul 01
1
general linear model and generalized linear model
Dear friends,
I searched the R site and found a lot of results on general linear model
and generalized linear model , and i was confused by them. Here, I only want
to get some concise answers on the following questions and i'll study it by
your hints:
1. Which function(package) could be used to fit the general linear model ?
2. Which function(package) could be used to fit the generalized
2006 Jul 03
1
how to get the studentized residuals in lm()
Dear friends,
In s-plus, lm() generates the the studentized residuals
automatically for us, and In R, it seems don't have the results: After
i fitted lm(), i use attibutes() to see the objects and didn't find
studentized residuals .
How to get the the studentized residuals in lm(),have i missed something?
thanks very much!
--
Kind Regards,
Zhi Jie,Zhang ,PHD
Department of Epidemiology
2007 Nov 08
2
question on image() function?
Dear friends,
My dataset is like the following:
x y mcpvalue
0.4603578 0.6247629 1.001
0.4603715 0.6247788 1.001
0.4603852 0.6247948 1.001
0.4110561 0.5664841 0.995
The x and y variables are unsorted.
I use the function image(x,y,mcpvalue) to generate a plot, but the error
is that "increasing 'x' and