# [R] Creating a maxtrix from "conditional prints"

Joris Meys jorismeys at gmail.com
Sun Jun 6 00:06:07 CEST 2010

```Use rbind? Not the most optimal solution, but it should get the job done.

# not tested
Code example:

out <- c()
for (x in 1:10) {
for (y in 1:10) {
qui <- ifelse((mac[,1] == x) & (mac[,5] == y) |  (mac[,1] == y) & (mac[,5]
== x), 1, NA)
quo <- cbind(mac,qui)
qua <- subset(quo, qui ==1)
if(nrow(qua) == 2)
print(qua)
out <- rbind(out,qua)
}}

On Fri, Jun 4, 2010 at 9:08 PM, EM <evilmastea at gmail.com> wrote:
> Hi guys :)
>
> I'm dealing with this problem, perhaps conceptually not that complex, but
> still - I'm stuck.
>
> Two columns, values 1<x<10, only integers. I want to check when the first
> column's index is identical to the second's (and vice versa). If that's
> true, I want to add a further column with value 1 (if true) or NA (if
> false).
> Thus, I obtain 100 matrices (for each columns I will have 1-1, 1-2, 1-3
> etc). Now, I want R to  consider only those matrices whose "new" column has
> value = 1 & whose total number of rows is equal to 2. I can get R to "print"
> this result inside the "for" cycle, yet I can't manage to build a single
> matrix, to store all the results altoghether - which is what I really want.
>
>
> Code example:
>
> for (x in 1:10) {
> for (y in 1:10) {
> qui <- ifelse((mac[,1] == x) & (mac[,5] == y) |  (mac[,1] == y) & (mac[,5]
> == x), 1, NA)
> quo <- cbind(mac,qui)
> qua <- subset(quo, qui ==1)
> if(nrow(qua) == 2)
> print(qua)
> }}
>
> result (wrong, now):
>
>     ricevente genere_r abo_r classieta_r donatore genere_d abo_d
> classieta_d    eta_d mismatch pra comp       mum qui
> [1,]         8        0     1           3        9        1     1
> 4 56.17437        2   1    1 -6.645437   1
> [2,]         9        1     1           2        8        0     1
> 3 48.77579        2   1    1 -5.905579   1
>     ricevente genere_r abo_r classieta_r donatore genere_d abo_d
> classieta_d    eta_d mismatch pra comp       mum qui
> [1,]         8        0     1           3       10        0     0
> 3 48.77579        2   1    1 -5.905579   1
> [2,]        10        0     2           5        8        0     1
> 3 48.77579        1   1    1 -5.391579   1
>     ricevente genere_r abo_r classieta_r donatore genere_d abo_d
> classieta_d    eta_d mismatch pra comp       mum qui
> [1,]         8        0     1           3        9        1     1
> 4 56.17437        2   1    1 -6.645437   1
> [2,]         9        1     1           2        8        0     1
> 3 48.77579        2   1    1 -5.905579   1
>     ricevente genere_r abo_r classieta_r donatore genere_d abo_d
> classieta_d    eta_d mismatch pra comp       mum qui
> [1,]         9        1     1           2       10        0     0
> 3 48.77579        0   1    1 -4.877579   1
> [2,]        10        0     2           5        9        1     1
> 4 56.17437        0   1    1 -5.617437   1
>
> what I'd like to get:
>
>     ricevente genere_r abo_r classieta_r donatore genere_d abo_d
> classieta_d    eta_d mismatch pra comp       mum qui
> [1,]         8        0     1           3        9        1     1
> 4 56.17437        2   1    1 -6.645437   1
> [2,]         9        1     1           2        8        0     1
> 3 48.77579        2   1    1 -5.905579   1
> [3,]         8        0     1           3       10        0     0
> 3 48.77579        2   1    1 -5.905579   1
> [4,]        10        0     2           5        8        0     1
> 3 48.77579        1   1    1 -5.391579   1
> [5,]         8        0     1           3        9        1     1
> 4 56.17437        2   1    1 -6.645437   1
> [6,]         9        1     1           2        8        0     1
> 3 48.77579        2   1    1 -5.905579   1
> [7,]         9        1     1           2       10        0     0
> 3 48.77579        0   1    1 -4.877579   1
> [8,]        10        0     2           5        9        1     1
> 4 56.17437        0   1    1 -5.617437   1
>
> (don't mind the values & names, this is just a small part of a longer
> algorithm)
>
>
>        [[alternative HTML version deleted]]
>
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> and provide commented, minimal, self-contained, reproducible code.
>

--
Ghent University
Faculty of Bioscience Engineering
Department of Applied mathematics, biometrics and process control

tel : +32 9 264 59 87
Joris.Meys at Ugent.be
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