Displaying 20 results from an estimated 10000 matches similar to: "Accessing elements of a list"
2011 Mar 01
2
Does POSIXlt extract date components properly?
I would like to use POSIX classes to store dates and extract components of
dates. Following the example in Spector ("Data Manipulation in R"), I
create a date
> mydate = as. POSIXlt('2005-4-19 7:01:00')
I then successfully extract the day with the command
> mydate$day
[1] 19
But when I try to extract the month
> mydate$mon
[1] 3
it returns the wrong month. And
2010 Mar 15
1
Eliminate border in wireframe plot
How can I eliminate the border drawn by default around a wireframe plot? I've tried using border=NA and box=FALSE to no avail.
Scott Waichler
Pacific Northwest National Laboratory
scott.waichler at pnl.gov
2009 Dec 29
4
subsetting by groups, with conditions
I have a data set similar to this:
P1id Veg1 Veg2 AreaPoly2 P2ID
1 p p 1 1
1 p p 1.5 2
2 p p 2 3
2 p h 3.5 4
For each group of "Poly1id" records, I wish to output (subset) the record
which has largest "AreaPoly2" value, but only if
2010 Mar 05
4
conditioning variable in panel.xyplot?
I wish to create a multipanel plot (map) from several datasets ("d" and
"q" in the example below). I can condition the main xyplot statement on
the "site" variable, but I don't know how to pass a conditioning variable
to panel.xyplot plot so that the x-y coordinates from dataset q are only
plotted at the appropriate site.
library(lattice)
d <-
2010 Jun 22
2
Lattice legend
I have a moderately complex graph with three panels. There are data points
plotted, and fitted lines are added using a panel function, which includes
"with(alt.data[[which.packet()[1]]]" statements. It all graphs out
beautifully, but none of the usual tricks to get the proper legend to plot
are working, i.e., using auto.key, key, etc.
One message I keep getting is
Error in
2011 May 04
1
adding columns to dataframes contained in a list
hi there,
I have a list of 5 identical dataframes:
mydf <- data.frame(x=c(1:5), y=c(21:25))
mylist <- rep(list(mydf),5)
and a factor variable with 5 levels:
foo <- c(letters[1:5])
foo <- as.factor(foo)
Question:
I'd like to add a new variable to each dataframe in the list, each
containing only one level of the factor variable. So mylist[[1]]
should have a new variable z
2008 Mar 13
3
Splitting a set of vectors in a list
I have a set of character vectors of uneven length
that I have stored in a list. I can easily enough get
any column of them using lapply but what I want is to
be able to create a matrix of them. Other than some
kind of brute force looping approach I have drawn a
blank.
Would somebody please suggest something? Thanks
Example.
mylist <- list(aa=c("cat","peach" ),
2012 Jun 28
3
loop through and modify multiple data frames
Hi
Newbie question:
I have a set of data frames that I want to do the same calculations on each.
I've found out that I can put them in a list and loop through the list
to do the calculation, but not put the results back into each
data.frame..
For example three data frames cats, dogs, birds
where >cats
name eats_kg
1 bob 3
2 garfield 4
3 chuck 6
and dogs and birds are similar but not
2007 Dec 13
2
Overlaying trellis xyplot on contourplot
Friends: I wish to overlay data points on a contour graph. The following
example produces a nice contour plot, but I have not mastered the concept
of using panel functions to modify plots. Can someone show me how to
overlay the data points (given after contour plot statement) on the
contourplot?
--Seth
model <- function(a,b,c,X1,X2) # provide model
function for contour
2009 Sep 18
1
xyplot: Can I identify groups but not use them for regression?
I wish to identify groups representing different treatments, but to plot
them and do a regression using a continuous variable ("cover")
ignoring the groupings.
d$year <- NA
d$year <-c(rep(2007,12), rep(2008,12))
d$treatment <- c(rep("A",4),rep("B",4),rep("C",4), rep("A",4), rep("B",4),
rep("C",4))
d$cover <-
2010 Sep 21
1
Doing operations by grouping variable
I'm writing an expression that requires searching a vector according to
group. As an example, I want to find the maximum value in each of 5
groups.
group=rep(1:5, each=5) # create grouping variable
variable=rnorm(25) # generate data
d <- data.frame(group,variable) # make data frame
2012 Mar 23
1
Remove wireframe outer box but keep ticks
I would like to eliminate the outer box around a lattice wireframe graph, but the usual recommended solution, which is to assign a color of 'transparent' to the axis.line parameter,
eliminates ticks if the 'arrows=F' command is used, as shown in the following example:
test = data.frame(expand.grid(c(1:10), c(1:10)))
z = test[,1] + test[,2]
test = cbind(test, z)
names(test) =
2009 Oct 25
3
NULL elements in lists ... a nightmare
I can define a list containing NULL elements:
> myList <- list("aaa",NULL,TRUE)
> names(myList) <- c("first","second","third")
> myList
$first
[1] "aaa"
$second
NULL
$third
[1] TRUE
> length(myList)
[1] 3
However, if I assign NULL to any of the list element then such
element is deleted from the list:
> myList$second <-
2010 Jun 08
3
more dates and data frames
Dear R People:
So thanks to your help, I have the following:
> dog3.df <- read.delim("c:/Users/erin/Documents/dog1.txt",header=FALSE,sep="\t")
> dog3.df
V1 V2
1 1/1/2000 dog
2 1/1/2000 cat
3 1/1/2000 tree
4 1/1/2000 dog
5 1/2/2000 cat
6 1/2/2000 cat
7 1/2/2000 cat
8 1/2/2000 tree
9 1/3/2000 dog
10 1/3/2000 tree
11 1/6/2000 dog
12 1/6/2000
2010 Jul 27
2
Sum list elements
Hi!
I have a list of 24 elements, all of the same type (dataframe, for example).
I am looking for an alternative to mylist[[1]] + mylist[[2]] + ... +
mylist[[24]] to obtain the sum.
Anyone can help me?
Thanks in advance.
Nicola S.
[[alternative HTML version deleted]]
2013 Feb 12
3
grabbing from elements of a list without a loop
Hello!
# I have a list with several data frames:
mylist<-list(data.frame(a=1:2,b=2:3),
data.frame(a=3:4,b=5:6),data.frame(a=7:8,b=9:10))
(mylist)
# I want to grab only one specific column from each list element
neededcolumns<-c(1,2,0) # number of the column I need from each element of
the list
# Below, I am doing it using a loop:
newlist<-NULL
for(i in 1:length(mylist) ) {
2013 Apr 29
3
rbinding some elements from a list and obtain another list
Hi everybody,
I have a list, where every element of this list is a data frame.
An example:
Mylist<-list(A=data.frame, B=data.frame, C=data.frame, D=data.frame)
I want to rbind some elements of this list.
As an example:
Output<-list(AB=data.frame, CD=data.frame)
Where
AB=rbind(A,B)
CD=rbind(C,D)
I’ve tried:
f<-function(x){
for (i in
2010 Apr 05
1
Deleting many list elements in one time
Hi guys, here is a simple thing I want to do but it doesn't work:
I have a vector of the element indexes that I want to delete called index
so when I write myList[[index]] <- NULL to delete these elements here is
what I get:
Error in myList[[index]] <- NULL :
more elements supplied than there are to replace
Isn't it possible to delete multiple elements?
-----
Anna Lippel
--
2015 May 04
2
Define replacement functions
Hello
I tried to define replacement functions for the class "mylist". When I test them in an active R session, they work -- however, when I put them into a package, they don't. Why and how to fix?
make_my_list <- function( x, y ) {
return(structure(list(x, y, class="mylist")))
}
mylist <- make_my_list(1:4, letters[3:7])
mylist
mylist[['x']] <- 4:6
2011 Sep 09
1
Adding groups to regression line panel function in Lattice
I wish to display a single-panel Lattice figure with grouped data and fitted regression lines. I don't seem to be able to get the
individual regression lines to display, e.g.;
d <- data.frame(q = rep(1:6, each=10), cc = rep(seq(10,100, 10),6)) # create data frame with group identifier 'q', independent variable cc
d$ba = d$q*0.1*d$cc + 5*rnorm(nrow(d))