Re: [R] searching for specific row in matrix
This should work for you:
create_bin_string - function(len)
+ {
+ sample(0:1, len, replace=T)
+ }
ROWS = 10
COLS = 5
set.seed(2)
pop = matrix(create_bin_string(ROWS*COLS), ROWS, COLS, byrow=T)
target=c(1, 1, 0, 1, 1)
# my population
print(pop)
[,1] [,2] [,3] [,4] [,5]
[1,]01101
[2,]10101
[3,]10100
[4,]11000
[5,]10100
[6,]00010
[7,]00111
[8,]11010
[9,]10001
[10,]11011
# determine which data matches
matches - t(pop) == target # 't' due to matching in column order
# colSums equal to COLS will indicate matches
which(colSums(matches) == COLS)
[1] 10
On Wed, Jun 11, 2008 at 7:58 AM, Esmail Bonakdarian [EMAIL PROTECTED] wrote:
Hi,
I have matrix of bits and a target vector. Is there an
efficient way to search the rows of the matrix for the target?
I am interested in the first row index where target is found.
Example:
source(lookup.R)
[,1] [,2] [,3] [,4] [,5]
[1,]10110
[2,]11010
[3,]00100
[4,]10011
[5,]10111
[6,]11001
[7,]10011
[8,]00111
[9,]01101
[10,]00010
target: 1 1 0 1 1
Should return -1 (or some other indicator) since the
target was not found in any of the rows.
source(lookup.R)
[,1] [,2] [,3] [,4] [,5]
[1,]00110
[2,]10000
[3,]10000
[4,]11000
[5,]11100
[6,]00110
[7,]01110
[8,]00110
[9,]11011
[10,]10100
target: 1 1 0 1 1
Should return 9 since the target was found in row 9
If the target is found, it is no longer necessary to keep
searching the rest of the matrix (which may be quite large)
The data/size etc may change of course, but target will
always have the same number of columns as the matrix.
I tried variations of which, and a for loop
comparing pop[i,] to target without much success, nor
did google yield any results. I am hoping someone here
can provide a suggestion.
Thanks,
EB
-
# Here is the code that generates the above data
create_bin_string - function(len)
{
sample(0:1, len, replace=T)
}
ROWS = 10
COLS = 5
pop = matrix(create_bin_string(ROWS*COLS), ROWS, COLS, byrow=T)
target=c(1, 1, 0, 1, 1)
# my population
print(pop)
# I am looking for the index of this in pop
# if present (else -1?)
cat(\ntarget: , target, \n)
##
## this is NOT working
## plus it would continue to search
## after it found the target
##
for(i in ROWS)
if (pop[i,] == target)
cat(\nfound in row: , i, \n\n)
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
Jim Holtman
Cincinnati, OH
+1 513 646 9390
What is the problem you are trying to solve?
__
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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Re: [R] searching for specific row in matrix
try this:
match.pat - function (mat, target, nomatch = -1) {
f1 - do.call(paste, c(as.data.frame(mat), sep = \r))
f2 - paste(target, collapse = \r)
ind - f1 %in% f2
if (any(ind)) which(ind)[1] else nomatch
}
##
set.seed(1234)
mat - matrix(sample(0:1, 50, TRUE), 10, 5)
targ1 - mat[2, ]
match.pat(mat, targ1)
targ2 - rep(0, 5)
match.pat(mat, targ2)
I hope it helps.
Best,
Dimitris
Dimitris Rizopoulos
Biostatistical Centre
School of Public Health
Catholic University of Leuven
Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
http://www.student.kuleuven.be/~m0390867/dimitris.htm
- Original Message -
From: Esmail Bonakdarian [EMAIL PROTECTED]
To: r-help@r-project.org
Sent: Wednesday, June 11, 2008 1:58 PM
Subject: [R] searching for specific row in matrix
Hi,
I have matrix of bits and a target vector. Is there an
efficient way to search the rows of the matrix for the target?
I am interested in the first row index where target is found.
Example:
source(lookup.R)
[,1] [,2] [,3] [,4] [,5]
[1,]10110
[2,]11010
[3,]00100
[4,]10011
[5,]10111
[6,]11001
[7,]10011
[8,]00111
[9,]01101
[10,]00010
target: 1 1 0 1 1
Should return -1 (or some other indicator) since the
target was not found in any of the rows.
source(lookup.R)
[,1] [,2] [,3] [,4] [,5]
[1,]00110
[2,]10000
[3,]10000
[4,]11000
[5,]11100
[6,]00110
[7,]01110
[8,]00110
[9,]11011
[10,]10100
target: 1 1 0 1 1
Should return 9 since the target was found in row 9
If the target is found, it is no longer necessary to keep
searching the rest of the matrix (which may be quite large)
The data/size etc may change of course, but target will
always have the same number of columns as the matrix.
I tried variations of which, and a for loop
comparing pop[i,] to target without much success, nor
did google yield any results. I am hoping someone here
can provide a suggestion.
Thanks,
EB
-
# Here is the code that generates the above data
create_bin_string - function(len)
{
sample(0:1, len, replace=T)
}
ROWS = 10
COLS = 5
pop = matrix(create_bin_string(ROWS*COLS), ROWS, COLS, byrow=T)
target=c(1, 1, 0, 1, 1)
# my population
print(pop)
# I am looking for the index of this in pop
# if present (else -1?)
cat(\ntarget: , target, \n)
##
## this is NOT working
## plus it would continue to search
## after it found the target
##
for(i in ROWS)
if (pop[i,] == target)
cat(\nfound in row: , i, \n\n)
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Disclaimer: http://www.kuleuven.be/cwis/email_disclaimer.htm
__
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] searching for specific row in matrix
Try this:
which(apply(t(m) == target, 2, all))
On Wed, Jun 11, 2008 at 8:58 AM, Esmail Bonakdarian [EMAIL PROTECTED]
wrote:
Hi,
I have matrix of bits and a target vector. Is there an
efficient way to search the rows of the matrix for the target?
I am interested in the first row index where target is found.
Example:
source(lookup.R)
[,1] [,2] [,3] [,4] [,5]
[1,]10110
[2,]11010
[3,]00100
[4,]10011
[5,]10111
[6,]11001
[7,]10011
[8,]00111
[9,]01101
[10,]00010
target: 1 1 0 1 1
Should return -1 (or some other indicator) since the
target was not found in any of the rows.
source(lookup.R)
[,1] [,2] [,3] [,4] [,5]
[1,]00110
[2,]10000
[3,]10000
[4,]11000
[5,]11100
[6,]00110
[7,]01110
[8,]00110
[9,]11011
[10,]10100
target: 1 1 0 1 1
Should return 9 since the target was found in row 9
If the target is found, it is no longer necessary to keep
searching the rest of the matrix (which may be quite large)
The data/size etc may change of course, but target will
always have the same number of columns as the matrix.
I tried variations of which, and a for loop
comparing pop[i,] to target without much success, nor
did google yield any results. I am hoping someone here
can provide a suggestion.
Thanks,
EB
-
# Here is the code that generates the above data
create_bin_string - function(len)
{
sample(0:1, len, replace=T)
}
ROWS = 10
COLS = 5
pop = matrix(create_bin_string(ROWS*COLS), ROWS, COLS, byrow=T)
target=c(1, 1, 0, 1, 1)
# my population
print(pop)
# I am looking for the index of this in pop
# if present (else -1?)
cat(\ntarget: , target, \n)
##
## this is NOT working
## plus it would continue to search
## after it found the target
##
for(i in ROWS)
if (pop[i,] == target)
cat(\nfound in row: , i, \n\n)
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40 S 49° 16' 22 O
[[alternative HTML version deleted]]
__
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] searching for specific row in matrix
Henrique Dallazuanna wrote:
Try this:
which(apply(t(m) == target, 2, all))
Wow! .. talk about concise! Neat! Thanks.
This will return all matches correct? So if I only wanted
the first I'd simply subscript [1] into it.
Do you think the fact that it searches the whole matrix instead
of stopping when it finds a match may slow it down?
This is my own solution I came up with in the meantime,
looks rather pedestrian compared to your one line, but it will
drop out immediately once if finds the target. Yours looks (based
simply on appearance :-) faster. Having no feel for the language
I may just have to time them.
I would assume that your solution would be faster simple since it's
using built-in language constructs which are optimized (and implemented
in C?) instead of my own interpreted way.
# return index of target in pop, else -1
searchPop - function(pop, target)
{
rows = length(pop[1,])
for(i in 1:rows)
{
result = (pop[i,] == target)
if (sum(which(result==FALSE)) == 0)
return(i)
}
return (-1)
}
idx=searchPop(pop, target)
if (idx 0)
{
cat(NOT found\n)
} else
cat(Found at position , idx, \n)
Esmail
--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40 S 49° 16' 22 O
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] searching for specific row in matrix
Dimitris Rizopoulos wrote:
try this:
match.pat - function (mat, target, nomatch = -1) {
f1 - do.call(paste, c(as.data.frame(mat), sep = \r))
f2 - paste(target, collapse = \r)
ind - f1 %in% f2
if (any(ind)) which(ind)[1] else nomatch
}
Thanks! More R for me to sink my teeth in :-) My own solution
doesn't seem to work quite correctly as I found out from some
further testing .. so the solutions posted here are much appreciated!
Esmail
__
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] searching for specific row in matrix
# determine which data matches matches - t(pop) == target # 't' due to matching in column order # colSums equal to COLS will indicate matches which(colSums(matches) == COLS) Neat! .. somewhat similar to the solution I came up with in the meantime, only yours works :-) Thanks Jim. Esmail __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
