similar to: subset by multiple columns satisfying the same condition

I have a huge matrix and need to delete certain rows. What I need to do is: 1.In each row, calculate the sum of jth column and (J+2)th column 2. If the sum is greater than 2 then that row needs to be deleted. I have a sample matrix and my codes here. It does remove some rows but when it does, it skips the next row and each time it deletes a row, the dimension changes so it gets out of bound. I

Dear All, I have a data frame with n columns: X1, X2, ., Xn. Now I want to create a new column: if X1 = X2 = . = Xn, the value is 1; Otherwise, the value is 0. How to do that in a quick way instead of doing (n choose 2) comparisons? Thank you, Frank [[alternative HTML version deleted]]

Hello, I have a question that is not directly related to R ... but I try to do it in R ;-) : I would like to generate a matrix Q satisfying (for a given Z, X and W) the two following conditions: t(Q)%*%Q=Z (1) XQ=W (2) where: Q is m rows and r columns X is p rows and m columns D is p rows and r columns C is r rows and r columns with m>p,r e.g: m=6, p=2 r=3

Hi, I wonder whether similarly to the very quick rowSums and colSums functions in the base package, one could add quick functions that calculate the min or max over rows / cols in a matrix. While apply(x,1,min) works, I found out by profiling a program of mine that it is rather slow for matrices with a very large number of rows. A quick functionality seems to be already there in the

Dear R people, I have a simple question to ask. Suppose I have a data.frame with two variables: one factor (x) and one numeric (y), I want to calculate the mean of y for each value of x. Although it's easy to do it within a for a loop, I believe there may be a concise way by using some kinds of "apply" functions. Could anyone tell me how to do that? Thank you. Frank

Hi, Please consider the following : x = c(1,3,NA,5) y = c(2,NA,4,1) min(x,y,na.rm=TRUE) # ok [1] 1 max(x,y,na.rm=TRUE) # ok [1] 5 sum(x,y,na.rm=TRUE) # ok [1] 16 pmin(x,y,na.rm=TRUE) # ok [1] 1 3 4 1 pmax(x,y,na.rm=TRUE) # ok [1] 2 3 4 5 psum(x,y,na.rm=TRUE) [1] 3 3 4 6 # expected result Error: could not find function "psum" # actual result

Dear R users: Is there a built-in and simple way to insert new columns after other columns in a dataframe? I.e. currently I have: V1 V2 V3 V4 [1,] [2,] Etc. But I want V1 V5 V2 V3 V4 [1,] [2,] Etc. Can this be done in one line? Jon Minton [[alternative HTML version deleted]]

In Mathematica there is a neat feature, where you can change the head of a list from "list" to say "+" and obtain a sum of the list elements. I can't find a way to sum a list of vectors of same length or list of matrices of the same dimension and was curious if something like that exists in R. do.call("+",list) doesn't work because "+" accepts only

Hi All, I have a data with a variable like this: Column 1 "123abc" "12cd34" "1e23" ... Now I want to do an operation that can split it into two variables: Column 1 Column 2 Column 3 "123abc" 123 "abc" "12cd34" 12 "cd34" "1e23" 1

Hello, all, I have a dataframe of three rows and umpteen columns. I want to show the maximum, minimum, and median with a vertical line and a central dot (I'd use a boxplot, but with only three data points, that's overkill; I can't just use points, because of overlap and some of the other data plotted on the graph). This works: > boxplot(data_frame,

I'm having trouble with something that looks easy. (And I'm sure it will be easier within about 1 minute of receiving my first response.) Thanks in advance. I have a collection of data frames that I need to add columns, do some calculations and then fill in the new columns. Since I have a large number of similar data frames I want to do this with functions to make the code more readable

Hi, I have a data.frame that is date ordered by row number - earliest date first and most current last. I want to create a couple of new columns that show the max and min values from other columns *so far* - not for the whole data.frame. It seems this sort of question is really coming from my lack of understanding about how R intends me to limit myself to portions of a data.frame. I get the

Hi, I need to keep a running count of events that have happened in my data.frame. I found a document called usingR that had an example of doing this for random coin flips and I tried to modify it. It seems to sort of work in the beginning, but then it stops and I don't understand why. I'm trying to duplicate essentially the Excel capability of =SUM($A$1:$A(Row number)) The example

Hi, Why doesn't R include a full Lapack but only a subset? My cda package (now archived) relying on RcppArmadillo has broken multiple times on CRAN over the past few years following updates in the underlying Armadillo library, Every time it follows the same pattern: Armadillo adds a function to solve a specialised linear system more efficiently, and the corresponding Lapack routine is not

Hi Folks, I want to export a dataframe's column classes to a list so that I can reinstantiate the dataframe from a CSV file in the future. (I know about save(), which I'm using in addition to this). what I want to do is the following: write.csv(myframe); col_classes = get_col_classes(myframe); write.csv(col_classes, "column_classes") ... time passes, R gets

I have a data frame somewhat like this: myframe <- data.frame (ID=c(2,3,4,5), Hunger =c(415,452,550,318 )) myframe Now I would like to add a column to the right which summarizes the values for Hunger somewhat to reduce the number of values: If the values for Hunger are between 300-400 I would like to insert the number 350, between 400-500 insert 450 between 500-600 insert 550 Does

Hello, I tried for about three hours now to solve this problem but I can't figure it out. I am sure someone knows how do it. At least I hope so. I have a data frame somewhat like this: myframe <- data.frame (ID=c("Ernie", "Ernie", "Bert", "Bert"), Timestamp=c("24.09.2012 09:00", "24.09.2012 09:00", "24.09.2012 10:00",

Dear R people, I have a very big tab-delim txt file with header and I only want to import several columns into R. I checked the options for "read.table" and only found "nrows" which lets you specify the maximum number of rows to read in. Although I can use some text editors (e.g., wordpad) to edit the txt file first before running R, I feel it?s not very convenient. The

The data set consists of two sets of matrices, as labelled by the columns, T's and C's. > xy x T1 T2 T3 T4 T5 C1 C2 C3 C4 C5 [1,] 50 0.00 0.00 33.75 0.00 0.00 0.00 36.76 0.00 35.26 0.00 [2,] 13 34.41 0.00 0.00 36.64 32.86 34.11 35.80 37.74 0.00 0.00 [3,] 14 35.85 0.00 33.88 36.68 34.88 34.58 0.00 32.75 37.45 0.00 [4,] 33 34.56

Hi everyone, I have another fairly simple question. I want to take the earliest of two dates from these two date columns. I've tried converting the dates to numbers and just get a vector full of NA's. I've also tried using the chron function to compare the two and have been unsuccessful. I then tried to use:temp.2 <- as.POSIXct(strptime(temp, '%d/%m/%Y')) where temp is