similar to: Sampling from a Data Frame

Displaying 20 results from an estimated 4000 matches similar to: "Sampling from a Data Frame"

2003 Mar 26
2
ifelse()
Hi, I'm not sure if this can be done but.. I know that with ifelse() I can do something like: ifelse(x <= 3, 1, 2) to go through each element in my vector x, and if x_i <= 3 substitute the number with 1 else with 2. Essentially I'll get a vector with 2 levels. Can I tweak it so I can get 3-levels? For example: if(x <= 3) then 1 elseif(3 < x <= 4) then 2
2003 Jun 01
1
Wording of "R Installation and Administration"
Hi, I hope I haven't got this wrong, but I don't think one needs Perl installed if they install the "precompiled" packages for Windows right? I'm just wondering if the first sentence in the "R Installation and Administration" can be re-worded a bit so newbies won't get confused.... ---------- Forwarded message ---------- Date: Mon, 2 Jun 2003 08:56:37 +1200
2003 May 25
1
Example Data Set(s) for nnet, rpart
Hi, I'm doing a presentation on Neural Networks and Tree-Based Models in two weeks, at the moment I'm looking for a data set to use in the presentation. What I would like to use is a good old data, like the Iris data, that is already known by every statisticians. MASS4 uses the cpus data in Chapter 8.10 and the Cushing's syndrome in Chapter 12.4. These two data sets plus the
2003 Mar 26
2
Plotting K-M Curve when have several strata
Hi, If I have: foo <- survfit(y ~ x) where y is a survival object and x is a n-level factor. The documentation says when I plot(foo), the confidence intervals will not be plotted (which I guess is understandable as otherwise the plot will get really messy). I tried to plot with confidence intervals by using: plot(foo, conf.int = TRUE) and indeed the resulting plot is messy. However
2003 Nov 26
4
strptime Usage
Hi, I have a column in a dataframe in the form of: > as.vector(SLDATX[1:20]) [1] "1/6/1986" "1/17/1986" "2/2/1986" "2/4/1986" "2/4/1986" [6] "2/21/1986" "3/6/1986" "3/25/1986" "4/6/1986" "4/10/1986" [11] "4/23/1986" "4/30/1986" "5/8/1986"
2003 May 19
2
To update() or not to update()?
Hi, Suppose I have: # Fit a base model d1.ph <- coxph(Surv(start, stop, event)~ ejec + diavol + score + smoking + beta + surg.done, data = data.frame(foo)) summary(update(d1.ph, . ~ . + td1)) summary(update(d1.ph, . ~ . + td2)) As I have many columns in my data frame, foo, called td's. e.g. td1, td2, td3, .... And I'd like to
2003 Apr 06
1
Change cex.axis in biplot()
Hi, If I do something like: biplot(x, cex.axis = .7) then it will only change the font size for axis 1 and 2, but not 3 and 4. Is there a way to change the fonts on axis 3 and 4? -- Cheers, Kevin ------------------------------------------------------------------------------ /* Time is the greatest teacher, unfortunately it kills its students */ -- Ko-Kang Kevin Wang Master of Science
2003 Apr 23
1
Plotting Factors -- Sorting x-axis
Hi, Say I have a factor with 20-levels: 1, 2, 3, ..., 20, called foo. If I do plot(foo) it will draw a barplot. But the x-axis is sorted alphanumerically, i.e. 1, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 2, 3, ..., 9, which is not what I want. I'd like to x-axis to be in the order of 1 ~ 20 numerically. So, the question is, how do I change the order on the x-axis in this case? --
2003 May 22
1
Getting the Bootstrap Error Rate of QDA
Hi, What does this mean when I have something like: > qda.boot <- boot(train, qda.bootstrap, R = 500) Error in qda.default(structure(data.matrix(x), class = "matrix"), ...) : Rank deficiency in group M with my qda.bootstrap() looks something like: > qda.bootstrap <- function(data, index) { + boot.qda <- qda(x = data[index, 2:9], group = data[index, 1]) + qda.pred
2003 Jun 07
1
Extracting Numbers from MANOVA output
Hi, Suppose I have: > summary(manova(plank.man)) Df Pillai approx F num Df den Df Pr(>F) plankton.new[, 1] 1 0.5267 9.8316 6 53 2.849e-07 *** Residuals 58 --- Signif. codes: 0 `***' 0.001 `**' 0.01 `*' 0.05 `.' 0.1 ` ' 1 My understanding is the MANOVA summary returns a list.
2003 Jun 10
1
Bootstraping with MANOVA
Hi, Does anyone know what the error message mean? > Boot2.Pillai <- function(x, ind) { + x <- as.matrix(x[,2:ncol(x)]) + boot.x <- as.factor(x[ind, 1]) + boot.man <- manova(x ~ boot.x) + summary(manova(boot.man))[[4]][[3]] + } > > man.res <- manova(as.matrix(pl.nosite) ~ + as.factor(plankton.new[,1]))$residuals > boot2.plank <-
2003 Apr 11
4
Can I improve the efficiency of my scan() command?
Hi, Suppose I use the following codes to read in a data set. ############################################### > rating <- scan("../Data/Rating.csv", + what = list( + usage = "", + mileage = 0, + sex = "", + excess = "", + ncd = "", +
2003 Mar 10
1
rpart returning only 1 node
Hi, This may actually be a theoretical question. When I tried to do the following: ########################################################## > colnames(rating.adclms) [1] "usage" "mileage" "sex" "excess" "ncd" [6] "primage" "minage" "drivers" "district" "cargroup" [11]
2003 Dec 15
3
Julian Dates
Hi, I'm a bit confused how julian() works. If I understand right, it returns the number of days since the origin. I have a vector: > SLDATX[1:10] [1] "1986-01-06" "1986-01-17" "1986-02-02" "1986-02-04" [5] "1986-02-04" "1986-02-21" "1986-03-06" "1986-03-25" [9] "1986-04-06"
2002 Apr 15
1
Re: Writting R Function
Hi, I think I found the problem. It lies in my Fortran program. Is there a way, after a DO loop, to make sure it does NOT return anything? Cheers, Kevin On Mon, 15 Apr 2002, Ko-Kang Kevin Wang wrote: > Date: Mon, 15 Apr 2002 17:27:20 +1200 (NZST) > From: Ko-Kang Kevin Wang <kwan022 at stat1.stat.auckland.ac.nz> > To: R Help <r-help at stat.math.ethz.ch> > Subject:
2003 Jun 08
6
Basic question on applying a function to each row of a dataframe
Hi, I have a function foo(x,y) and a dataframe, DF, comprised of two vectors, x & w, as follows : x w 1 1 1 2 2 1 3 3 1 4 4 1 etc I would like to apply the function foo to each 'pair' within DF e.g foo(1,1), foo(2,1), foo(3,1) etc I have tried >apply(DF,foo) >apply(DF[,],foo) >apply(DF[DF$x,DF$w],foo) However, none of the above worked. Can anyone help ?
2002 Sep 18
2
More on list to data frame (was: Re: List to Data Frame
Hi, Now suppose I have just one list called FOO, which has 25 objects, e.g.: [[1]] 1 2 3 4 5 [[2]] 6 7 8 9 10 . . . And I want to do something like: FRED <- data.frame(cbind(unlist(FOO[[1]]), unlist(FOO[[2]]), # ... for all 25 subsets )) Is it possible to do this, without doing unlist(FOO[[i]]) 25
2002 Jun 08
2
More on for() Loop...
Hi, Say I want to do something like fitting 10 different sized trees with rpart() function. The only modification I need to do is to set 10 different cp's, which I have in a vector called foo. Can I do something like: for(i in 1:10) { rpart(y ~ ., cp = foo[i], data = mydata) } My problem is, I wish to save the 10 rpart objects into 10 different names, my.rpart1 ~ my.rpart10, for
2003 Apr 08
5
Help on smooth.spline?
Hey, R-listers I was recommended to try using smooth.spline function for estimating 2-Dimensinal curve given a data set. So will you please tell me where to get this R function? Or which package provides this function? Thanks for your point. Fred
2002 Oct 01
1
Cleveland's Cut-and-Stack Plot
Hi, Is there a function in R that does Cleveland's Cut-and-Stack plot (Page 190 -- 191, The Elements of Graphing Data, William S. Cleveland)? Or do I need to do it the hard way, i.e. set par(mfrow = c(m, n)) then do it one-by-one? (I have a time series data set that is almost identical to the description in Cleveland's book, hence I'm interested in trying the Cut-and-Stack plot)