PHP: combine arrays

PHP: combine arrays

What is the easiest/best way in PHP to combine arrays like this:
From:
Array A:
idA,valueA1,valueA2,...
idB,valueB1,valueB2,...
idC,valueC1,valueC2,...
Array B:
idA,valueAx,valueA2y,...
idC,valueCx,valueC2y,...
idD,valueDx,valueD2y,...
To:
idA,valueA1,valueA2,...,valueAx,valueA2y,...
idB,valueB1,valueB2,...,,,...
idC,valueC1,valueC2,...,valueCx,valueC2y,...
idD,,,...,valueDx,valueD2y,...
Thanks for your help!