Multidimensional Array Multiple Sort

[djkilgus]

I have a multidimensional array that I want to sort by "price" then by "date".  Here is an example of the array:

$productArray   = array ( array ("Bus", "1/1/2010", 15.99),
                                        array ("Train", "2/1/2010", 14.99),
                                        array ("Car", "3/1/2010", 18.00),
                                        array ("Plane", "3/1/2010", 15.99),
                                        array ("Bike", "3/1/2010", 9.99),
                                        array ("Truck", "1/1/2010", 19.99)
);
//sort by date
function sortElement1Asc($x, $y)
{
if ( $x[1] == $y[1] )
		return 0;
        else if ( $x[1] < $y[1] )
		return -1;
        else
		return 1;
}
//sort by price
function sortElement2Asc($x, $y)
{
if ( strtotime($x[2]) == strtotime($y[2]) )
		return 0;
else if ( strtotime($x[2]) < strtotime($y[2]) )
		return -1;
else
		return 1;
}
usort($productArray, 'sortElement1Asc');
usort($productArray, 'sortElement2Asc');

 

Unfortunately this is just sorting by price (or whatever i sort last).

 

Any ideas?

[PFMaBiSmAd]

The comment above each function doesn't match what the code is doing in each function, which also results in the wrong array element number being accessed by the code in each function.

[djkilgus]

PFMaBiSmAd, thanks for the response.  The individual sort functions are working fine.  If I comment out usort($productArray, 'sortElement1Asc'); and run the code it sorts by price ascending and vice versa with the other usort line.  I just can't get a sort by date, sort by price to work.

[PFMaBiSmAd]

I recommend that you play computer and proofread your code and comments in your code to see if it is logically doing what you expect.

[kicken]

 

Your two sorting functions are completely separate and have no relation to each other.

 

When you call usort($productArray, 'sortElement1Asc'); your sorting the array by the date.

 

Next, when you call usort($productArray, 'sortElement2Asc'); your sorting the array by the price, but in the process you completely overwrite the previous sorting.  This second call is a completely separate process with no relation to the previous sort.

 

What you need to do to sort by both is create one single function which will do the sorting you need.  First, compare the price.  If they differ, return -1 or 1 accordingly.  If they are equal, move on to your second condition on the date.  Compare the dates and return -1, 0, or 1 as appropriate.

 

[djkilgus]

kicken,

 

Thank you for the constructive reply.  Thanks to you I figured it out.  For anyone who is interested here is the correct (single) sort function:

 

function sortByDateThenByPrice($x, $y)
{
if ( $x[1] == $y[1] )
     if ( $x[2] == $y[2] )
          return 0;
     else if ( $x[2] < $y[2] )
          return -1;
     else
          return 1;
else if ( $x[1] < $y[1] )
     return -1;
else
     return 1;
}
usort($productArray, 'sortByDateThenByPrice');