How to select random elements from row sequentially from matrix but if the all elements in row selected don't select the same row again - matlab

Question

let say i have this matrix
m =
3 1 2 4 6 5
2 3 5 6 1 4
3 4 6 1 2 5
2 1 3 4 5 6
3 2 5 6 1 4
2 4 6 1 5 3
which have 6 raw's and 6 column
i want to select randomly froms raw sequentially the first selection will choose the first
element in that raw
so if by random after covering all the elements in raw 5 i don't want the program to come
to select from it again
example if random iteration 1 select raw1 it will go to the first element in raw1 which is
in column 1
if by random in iteration 2 it select the same raw1 again it will select the the second
element in raw1 which is in column 2
so if i reached column 6 in raw1 and after it the iteration selected raw1 again but my
matrix is 6 column so i want to select by random another raw which is not reached till the
sixth column
let say if each time a raw is selected i will make a value in that column which equal to
one
so if i run 20 iterations
JM =
1 1 1 1 1 0
1 1 0 0 0 0
1 1 1 1 0 0
1 1 0 0 0 0
1 1 1 0 0 0
1 1 1 1 0 0
by luck i didn't reach the sixth column in any of the raws
but if
JM =
1 1 1 1 1 0
1 1 1 1 0 0
1 1 0 0 0 0
1 1 1 1 1 1
1 0 0 0 0 0
1 1 0 0 0 0
Attempted to access m(5,7); index out of bounds because size(m)=[6,6].
how to continue random selection without coming to that raw which already full filled like
that raw 4 is already full filled
i hope it is easy to understand
iam using this method to create chromosome
which is in the form
m raw colmun =machine job operation
thanks
iam using matlab

Answer 1

I can see three slightly different methods to achieve this.
You should create an array of integers to store the information containing amount of elements you already took from each raw. Lets assume your matrix is [n*n] so the array will be [n]. Lets call it a[n]
first method:
Generate random raw number rNumber.
Check if you can take elements from this raw ( if(rNumber] < n) ). If you can't take an element then go to (1). Otherwise continue to (3)
Take an element m[rNumber][a[rNumber]] and increment a[rNumber]
second method:
Generate random raw number rNumber.
Check if you can take elements from this raw ( if(rNumber] < n) )
If you can't take an element then go to increment rNumber and go to (2). Otherwise continue to (4)
Take an element m[rNumber][a[rNumber]] and increment a[rNumber]
The last method also need to store the amount of raws where you took all the elements rawCount.
Generate random raw number rNumber between 0 and n-rawCount-1
Enumerate through all raws while currentRaw < rNumber. If a[currentRaw] < n then increment currentRaw
Take an element m[currentRaw][a[currentRaw]] and increment a[currentRaw]
If a[currentRaw] = n then increment rawCount

Answer 2

here is something that i wrote in c++. hope this is what were you looking for. don't hesitate to ask if you don't understand something
#include "stdafx.h"
#include<fstream>
#include<ctime>
#include<iostream>
using namespace std;
ifstream f("stack2.in");
ofstream g("stack2.out");
int a[10][10];
int solution[100],n,m,index =0;
void build(int n,int m)//create a MxN matrix, and fill it with values
{
int zz = 1;
for(int i=0;i<n;i++)
for(int j=0;j<m;j++)
{
a[i][j]= zz;
zz++;
}
}
void solve()
{
srand((unsigned)time(0));
int i,j;//column and line
while(index<m*n)
{
i = (rand()%10);//get random values for column and line
j = (rand()%10);
if(a[i][j]!=0) //if the value of matrix[i][j] is not 0, means that this value is new, so we add it to the solution list
{
solution[index]=a[i][j];
index++;
a[i][j]=0; //set the value from matrix[i][j] to 0 so we don't 'visit' again
}
else if(i<=n) //if the value from the matrix[i][j] is equal to 0, we start searching on the line of of i for values that are not 0
{
while(j<m)
{
if(a[i][j+1]!=0) //if matrix[i][j+1] has not been visited before, we add it to the solution, set it to zero and exit the while
{
solution[index]= a[i][j+1];
a[i][j+1]=0;
index++;
j=m; //exit the while
}
else
j++; //keep searching for a value on that line
}
}
}
for(int i=1;i<=m*n;i++)//print the list with random values
g<<solution[i]<<" ";
}
int main()
{
n=10;//or read the values from stack2.in using f>>n>>m
m=10;//in the file should be written on the same line, number of lines and columens of the matrix eg.: 5 7
build(n,m);
solve();
return 0;
}