Displaying 20 results from an estimated 10000 matches similar to: "when use which()"
2009 Nov 22
3
Define return values of a function
I have created a function to do something:
i <- factor(sample(c("A", "B", "C", NA), 793, rep=T, prob=c(8, 7, 5,
1)))
k <- factor(sample(c("X", "Y", "Z", NA), 793, rep=T, prob=c(12, 7, 9,
1)))
mytable <- function(x){
xtb <- x
btx <- x
# do more with x, not relevant here
cat("The table has been created,
2009 Mar 06
4
Summary grouped by factor
### example:start
v <- sample(rnorm(200), 100, replace=T)
k <- rep.int(c("locA", "locB", "locC", "locD"), 25)
tapply(v, k, summary)
### example:end
... (hopefully) produces 4 summaries of v according to k group
membership. How can I transform the output into a nice table with the
croups as columns and the interesting statistics as lines?
Thx,
2009 Mar 11
3
chisq.test: decreasing p-value
A Likert scale may have produced counts of answers per category.
According to theory I may expect equality over the categories. A
statistical test shall reveal the actual equality in my sample.
When applying a chi square test with increasing number of repetitions
(simulate.p.value) over a fixed sample, the p-value decreases
dramatically (looks as if converge to zero).
(1) Why?
(2) (If
2009 Mar 07
2
Recode factor into binary factor-level vars
How to I "recode" a factor into a binary data frame according to the
factor levels:
### example:start
set.seed(20)
l <- sample(rep.int(c("locA", "locB", "locC", "locD"), 100), 10,
replace=T)
# [1] "locD" "locD" "locD" "locD" "locB" "locA" "locA" "locA"
2010 Nov 17
2
slicing list with matrices
A list contains several matrices. Over all matrices (list elements) I'd like to access one matrix cell:
m <- matrix(1:9, nrow=3, dimnames=list(LETTERS[1:3], letters[1:3]))
l <- list(m1=m, m2=m*2, m3=m*3)
l[[3]] # works
l[[3]][1:2, ] # works
l[[1:3]][1, 1] # does not work
How can I slice all C-c combinations in the list?
S?ren
--
S?ren Vogel, Dipl.-Psych. (Univ.), PhD-Student, Eawag,
2009 Mar 08
1
Summary of data.frame according to colnames and grouping factor
A dataframe holds 3 vars, each checked true or false (1, 0). Another
var holds the grouping, r and s:
### start:example
set.seed(20)
d <- data.frame(sample(c(0, 1), 20, replace=T), sample(c(0, 1), 20,
replace=T), sample(c(0, 1), 20, replace=T))
names(d) <- c("A", "B", "C")
e <- rep(c("r", "s"), 10)
### end:example
How do I get the
2008 Sep 07
2
Regression with nominal data
Hi,
y is nominal (3 categories), x1 to 3 is scale. What I want is a
regression, showing the probability to fall in one of the three
categories of y according to the x. How can I perform such a
regression in R?
Thanks for your help
S?ren
2010 Jan 29
2
cbind, row names
Hello,
I read the help as well as the examples, but I can not figure out why
the following code does not produce the *given* row names, "x" and "y":
x <- 1:20
y <- 21:40
rbind(
x=cbind(N=length(x), M=mean(x), SD=sd(x)),
y=cbind(N=length(y), M=mean(y), SD=sd(y))
)
Could you please help?
Thank you
S?ren
2010 Apr 16
2
Return a variable name
Hello,
how can I return the name of a variable, say "a$b", from a function?
fun <- function(x){
return(substitute(x));
}
a <- data.frame(b=1:10);
fun(a$b)
... returns a$b, but this is a type language, thus I can't use it as a
character string, can I? How?
Thanks for help,
S?ren
2010 May 08
2
Adding NAs to data.frame
Hello, after the creation of a data.frame I like to add NAs as follows:
n <- 743;
x <- runif(n, 1, 7);
Y <- runif(n, 1, 7);
Ag6 <- runif(n, 1, 7);
df <- data.frame(x, Y, Ag6);
# a list with positions:
v <- apply(df, 2, function(x) sample(n, sample(1:ceiling(5*n/100), 1), repl=F));
# a loop too much?
for (i in 1:length(df)){
df[unlist(v[i]), i] <- NA;
}
summary(df);
This
2009 Feb 27
2
add absolute value to bars in barplot
Hello,
r-help at r-project.orgbarplot(twcons.area,
beside=T, col=c("green4", "blue", "red3", "gray"),
xlab="estate",
ylab="number of persons", ylim=c(0, 110),
legend.text=c("treated", "mix", "untreated", "NA"))
produces a barplot very fine. In addition, I'd like to get the
2008 Oct 09
2
Plot grouped histograms
r11 -- r16 are variables showing a reason for usage of a product in 6
different situations. Each variable is a factor with 4 levels imported
from a SPSS sav file with labels ranging from "not important" to "very
important", and NA's for a sample of N = 276.
(1) I need a chi square test of independence showing that the reason
does not differ depending on the
2009 Nov 13
1
shrink list by mathed entries
Hello
a <- c("Mama", "Papa", "Papa; Mama", "", "Sammy; Mama; Papa")
a <- strsplit(a, "; ")
mama <- rep(F, length(a))
mama[sapply(a, function(x) { sum(x=="Mama") }, simplify=T) > 0] <- T
papa <- rep(F, length(a))
papa[sapply(a, function(x) { sum(x=="Papa") }, simplify=T) > 0] <- T
# ... more
2010 Dec 03
1
Linear separation
In https://stat.ethz.ch/pipermail/r-help/2008-March/156868.html I found what linear separability means. But what can I do if I find such a situation in my data? Field (2005) suggest to reduce the number of predictors or increase the number of cases. But I am not sure whether I can, as an alternative, take the findings from my analysis and report them. And if so, how can I find the linear
2009 Mar 25
2
pca vs. pfa: dimension reduction
Can't make sense of calculated results and hope I'll find help here.
I've collected answers from about 600 persons concerning three
variables. I hypothesise those three variables to be components (or
indicators) of one latent factor. In order to reduce data (vars), I
had the following idea: Calculate the factor underlying these three
vars. Use the loadings and the original var
2008 Oct 07
1
read.spss: variable.labels
Hi,
how can I attach variable labels originally read by read.spss() to the
resulting variables?
<pre>
X <- read.spss('data.sav', use.value.labels = TRUE, to.data.frame =
TRUE, trim.factor.names = TRUE, trim_values = TRUE, reencode = "UTF-8")
names(X) <- tolower(names(X))
attach(X)
</pre>
Thank you
S?ren
2009 Feb 27
1
cross tabulation: convert frequencies to percentages
Hello,
might be rather easy for R pros, but I've been searching to the dead
end to ...
twsource.area <- table(twsource, area, useNA="ifany")
gives me a nice cross tabulation of frequencies of two factors, but
now I want to convert to pecentages of those absolute values. In
addition I'd like an extra column and an extra row with absolute sums.
I know, Excel or the
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
2015 May 04
1
Define replacement functions
No. I fixed that, the NAMESPACE file now contains:
S3method("[[<-", mylist)
S3method("$<-", mylist)
It still does not work. I also created a print method (print.mylist) which did work out of the box, regardless of being in the NAMESPACE file or not. Could it be somehow in here (also in my NAMESPACE file):
exportPattern("^[[:alpha:]]+")
Or could it be that
2011 Sep 10
1
Get previous R digest volumes/issues
Hello, (how) can I download/re-retrieve/order previous R-** digest volumes/issues to my mailbox for local browsing? Thank you, S?ren