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This is some interesting: > -8^(1/3) [1] -2 > x=(-8:8) > y=x^(1/3) > y [1] NaN NaN NaN NaN NaN NaN NaN NaN 0.000000 1.000000 [11] 1.259921 1.442250 1.587401 1.709976 1.817121 1.912931 2.000000 So, can anybody explain this?! (Why is x[1]^(1/3)=y[1]=NaN, but -8^(1/3)=-2?) Thx!!! [[alternative HTML version deleted]]

deaRs, I want to build a covariance matrix out of the data from a binary file, that I can read in chunk by chunk, with each chunk containing a single observation vector X. I wonder how to do that most efficiently, avoiding the calculation of the full symmetric matrices XX'. The trivial non-optimal approach boils down to something like: Q <- matrix(rnorm(100000),ncol=200) M <-

I am pretty new to R. So this may be an easy question for most of you. ? I would like to calculate the squared distances of a large set (let's say 20000) of vectors (let's say dimension of 5) to a fixed vector. ? Say I have a data frame MY_VECTORS with 20000 rows and 5 columns, and one 5x1 vector y. I would like to efficiently calculate the squared distances?between each of the 20000

Hi, I am trying to plot several columns in different graphs in columns and rows. The first column of my data file is the time, and the third is the 'elevation angle' with 19 different numbers. I would like to plot the rest of the columns with the x axis as time and the individual angles in different colours. Here is the code I am using right now. It plots the different columns with time,

Dear R-helpers, I know how to use unique to select unique rows, e.g. unique.rows<-unique(dataframe) but I would like to select those rows that are unique only only TWO of my dataframe's columns (so, two rows with the same value on these two columns would not be kept, even if they had different values in other columns). For example, I have a dataframe with 10 columns, two of which are

Hi, I'm trying to set the minimum and maximum in a parallel plot, but trying xlim=c(-1,1) gives strange results. Am I missing something? The call I give is: parallel(~X[,c(6,9,12,15,18)]|X$ff,X,panel=panel.parallel.new,groups=X$protein,layout=c(3,1),xlim=c(-1,1)) Besides, I would like to add a reference line to the plot, but can't find how to do that. I hope someone can give me a

Dear all, I have a large matrix with about 2500 variables, and 100 rows. I would like to calculate the means of the every 10 variables starting from 1:2500 and saving the results as a vector or matrix. How can I do that? Alternatively, How can I create 250 subset matrices in the order of variables 1:2500 in groups of 10 from the single matrix which had initially 2500 variables ? I guess I have

Dear R-users, I would like to apply a function (more precisely sd()) over the third dimension of a three-dimension array. The function apply would be interesting but the chosen function can only be applied on the rows and columns of the array according to the help file. I can use a loop to cut the array in matrices and then use apply for each replication, but it's not very nice. A small

Hello, Recently, the following problem started happening with a particular samba server: If i have a file open for reading (say, a pdf in xpdf) and then try to write to it (say, through recompiling a latex document) it complains that it cannot open the file for writing. this seems like a file lock issue but I am unsure where it is happening. My previous usage should be perfectly safe since

Hello, I am a newcomer to R and therefore apologize for posting such a basic question. I am trying to multiply 2 matrices t(X1)%*%X1, where t(X1) is: 1 2 3 4 5 8 12 13 20 24 26 27 31 33 34 36 37 40 41 42 45 46 47 48 49 ones 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Shadow 0 1 1 1 1 1 1 1 0 1 1 1 1 0 1 0

Hello! I'm trying to build a lower triangular matrix (with zeros in the diagonal) from a particular dataframe. The matrix I have to construct has 203 rows and 203 columns and that makes 20503 values to be included within (that's why I can't do it manually). To illustrate the dataframe I have, I'll give you an example of a dataframe and matrix with dimensions 6x6 (to make it

Dear all, I admit this is not anything to do R and even with Statistics perhaps. Strictly speaking this is a math related question. However I have some reasonable feeling that experts here would come up with some elegant suggestion to my question. Here my question is: What is sum of all Integers? I somewhere heard that it is Zero as positive and negative integers will just cancel each other out.

Dear R experts, How to find out the index of minimum or maxmum number in a vetor or data.frame? For example, a= n price 1 50 -2 100 0 200 -1 300 ...... I want to find out the row which the n is the smallest or largestest and extract the price. Thanks Ted -- View this message in context:

I've been wondering what L means in the R computing context, and was wondering if someone could point me to a reference where I could read about it, or tell me what it's called so that I can search for it myself. (L by itself is a little too general for a search term). I encounter it in strange places, most recently in the "save" documentation. save(..., list = character(0L),

Hi, i am using spatstat package for spatial data analysis and now i have a problem to create a point pattern. The points are in file "points.txt" (first column for Latitude and second column for Longitude ) and I imported them and separated each columns in two arrays x and y. If I plots x and y ( e.g plot(x,y) ) the result appears in square area without problems and the scale is

I'm trying to create a graph where different cells of a grid (a shapefile) will be painted with a color share scale, where the most easy way is to use gray(). Can I somehow get a vector (gradient) of colors, a vector of colors with other methods but gray()? I'm doing this until now quad_N_sp <-

Dear all, I have been trying to convert coordinates from longitude/latitude to utm but I got an error. As soon as the longitude coordinate is greater than 90, I get the folloowing error message: "error in pj_transform: latitude or longitude exceeded limits" Here is what I did: SP<-SpatialPoints(cbind(126.59,-14.30),proj4string=CRS("+proj=longlat"))

Hi all, I need a little help for construct an state's map on R. The first problem is to get the data. I have a datafile of longitude and latitude in the follow format: trajectory latitude longtude T -22.045618 -51.287056 T -22.067078 -51.265888 T -22.067039 -51.207249 T -22.059690 -48.089695 T -22.075529 -48.074608 T -22.072460 -48.044472 T -22.062767 -48.298473 T -22.077349

I have 100 data files, which contains very huge data sets of location details ( e.g latitude, longitude, time, temp) Now I would like to save the all data of these 100 files in r object, so I can reload data any time. * Every file has different length of data latitude <- NULL longitude <- NULL time <- NULL temp <- NULL for ( i in 1:100) { data<-

Dear all, I have a grid of 720 columns by 360 rows of global population density values, and hope to convert this to column format using the 'melt' command in the 'reshape' package. I'm not receiving any errors as such, but when the code has finished running, my output looks like this: > head(PopDens.long) Latitude Longitude PopDensity 1 -84.75 V1 0 2