age-
From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
Behalf Of Dimitris Rizopoulos
Sent: Thursday, October 08, 2009 6:28 AM
To: joris meys
Cc: r-help@r-project.org; Rama Ramakrishnan
Subject: Re: [R] Need a vectorized way to avoid two nested FOR loops
Another approach is:
rg [mailto:r-help-boun...@r-
project.org] On
Behalf Of Dimitris Rizopoulos
Sent: Thursday, October 08, 2009 6:28 AM
To: joris meys
Cc: r-help@r-project.org; Rama Ramakrishnan
Subject: Re: [R] Need a vectorized way to avoid two nested FOR loops
Another approach is:
n <- 20
set.seed(2)
x &l
.@r-project.org] On
Behalf Of Dimitris Rizopoulos
Sent: Thursday, October 08, 2009 6:28 AM
To: joris meys
Cc: r-help@r-project.org; Rama Ramakrishnan
Subject: Re: [R] Need a vectorized way to avoid two nested FOR loops
Another approach is:
n <- 20
set.seed(2)
x <- as.data.frame(matrix(sample(1
Another approach is:
n <- 20
set.seed(2)
x <- as.data.frame(matrix(sample(1:2, n*6, TRUE), nrow = n))
x.col <- c(1, 3, 5)
values <- do.call(paste, c(x[x.col], sep = "\r"))
out <- lapply(seq_along(ind), function (i) {
ind <- which(values == values[i])
ind[!ind %in% i]
})
out
Best,
Dimit
Neat piece of code, Jim, but it still uses a nested loop. If you order
the matrix first, you only need one passage through the whole matrix
to find the information you need.
Off course I don't take into account the ordering. If the ordering
algorithm doesn't work in linear time, then it doesn't re
I answered the wrong question. Here is the code to find all the
matches for each row:
n <- 20
set.seed(2)
# create test dataframe
x <- as.data.frame(matrix(sample(1:2,n*6, TRUE), nrow=n))
x
x.col <- c(1,3,5)
# match against all the other rows
x.match1 <- apply(x[, x.col], 1, function(a){
.ma
Here is one way of doing it:
> n <- 20
> set.seed(2)
> # create test dataframe
> x <- as.data.frame(matrix(sample(1:2,n*6, TRUE), nrow=n))
> x
V1 V2 V3 V4 V5 V6
1 1 2 2 2 1 1
2 2 1 1 2 2 1
3 2 2 1 2 1 2
4 1 1 1 1 1 2
5 2 1 2 2 1 1
6 2 1 2 1 2 2
7 1 1
7 matches
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