Is it possible to swap two elements of an array? for example like swap
rows in the matrix:
[1 5 7 3]
[2 6 2 5]
[6 5 1 7]
where I make a matrix as an array of arrays. where the inner arrays are
the rows of the matrix. so the above could be coded as:
A = [
[1,5,7,3],
[2,6,2,6],
[6,5,1,7]
]; 5 1096
greenflame wrote: Is it possible to swap two elements of an array? for example like swap rows in the matrix:
[1 5 7 3] [2 6 2 5] [6 5 1 7]
where I make a matrix as an array of arrays. where the inner arrays are the rows of the matrix. so the above could be coded as:
A = [ [1,5,7,3], [2,6,2,6], [6,5,1,7] ];
Below is some commented code with alerts to show what is happening
- you can safely remove the alerts.
You may want to check that A, A[r1] and A[r2] actually exist before
trying to swap them.
function swapRows( A, r1, r2 ){
var i = A.length;
alert(A.join('\n'));
A[i] = A[r1]; // Copy r1 to an extra element
alert(A.join('\n'));
A[r1] = A[r2]; // Copy r2 into r1
alert(A.join('\n'));
A[r2] = A[i]; // Put remembered r1 into r2
alert(A.join('\n'));
delete A[i]; // Remove copy of r1
alert(A.join('\n'));
}
B = [
[ 1, 2, 3 ],
[ 4, 5, 6 ],
[ 7, 8, 9 ]
];
swapRows( B, 0, 2 );
--
Rob
RobG wrote:
[...] function swapRows( A, r1, r2 ){ var i = A.length; alert(A.join('\n')); A[i] = A[r1]; // Copy r1 to an extra element alert(A.join('\n')); A[r1] = A[r2]; // Copy r2 into r1 alert(A.join('\n')); A[r2] = A[i]; // Put remembered r1 into r2 alert(A.join('\n')); delete A[i]; // Remove copy of r1 alert(A.join('\n'));
Forgot to mention that as A is just a reference to B, whatever we do
to A also happens to B, so:
alert(B.join('\n'));
shows that B now has its rows swapped.
[...]
--
Rob
greenflame wrote: Is it possible to swap two elements of an array?
Sure, array's are read/write, so just use a temporary var while
swapping so you don't lose one of the array items.
Example:
<script>
var a1 = [1,2,3];
var a2 = [4,5,6];
var aMatrix = [a1, a2];
alert("before swap:\n"+aMatrix.join("\n"));
var aTemp = aMatrix[0];
aMatrix[0] = aMatrix[1];
aMatrix[1] = aTemp;
alert("after swap:\n"+aMatrix.join("\n"));
</script>
greenflame said: Is it possible to swap two elements of an array? for example like swap rows in the matrix:
[1 5 7 3] [2 6 2 5] [6 5 1 7]
where I make a matrix as an array of arrays. where the inner arrays are the rows of the matrix. so the above could be coded as:
A = [ [1,5,7,3], [2,6,2,6], [6,5,1,7] ];
Certainly.
But I can't be more specific without more than a "for example".
I had a problem with the part where you remove the last row. It didnt
remove it, well yes but no. Anyway I fixed it by using the pop command.
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