<?php
 
// Array de objetos como fornecido no exemplo.
$produtos = [
    (object)[
        'produto' => '000001', 'var1' => 'LR', 'var2' => 'G', 'estoque' => 4.0000
    ],
    (object)[
        'produto' => '000001', 'var1' => 'AZ', 'var2' => 'G', 'estoque' => -4.0000
    ],
    (object)[
        'produto' => '000001', 'var1' => 'VD', 'var2' => 'G', 'estoque' => 0.0000
    ],
    (object)[
        'produto' => '000001', 'var1' => 'BR', 'var2' => 'G', 'estoque' => 17.0000
    ],
    (object)[
        'produto' => '000001', 'var1' => 'VR', 'var2' => 'G', 'estoque' => 0.0000
    ],
    // ... resto dos objetos
];
 
$resultado = [];
 
foreach ($produtos as $produto) {
    // Obtendo o tamanho (último caracter de var2)
    $tamanho = substr($produto->var2, -1);
 
    // Utilizando o operador de coalescência nula (??) para simplificar a inicialização dos arrays.
    $resultado[$produto->produto][$produto->var1][$tamanho] = ($resultado[$produto->produto][$produto->var1][$tamanho] ?? 0) + $produto->estoque;
}
 
// Para visualizar o resultado
echo "<pre>";
print_r($resultado);
echo "</pre>";
 

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