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    <h2>Your specific error (probably)</h2> <p>You do not test against nil values. Any non-initialized table (= array in this case) members are <code>nil</code> by definition. And comparing <code>nil</code> with a number will generate an error:</p> <pre><code>lua: attempt to compare nil with number </code></pre> <p>However, as you seem unable to provide the <em>actual</em> error message, this is only a guess. Do not take me wrong these are errors in your code, but there could be <em>something else</em> wrong that I overlooked. Anyway here are some comments along with your code to show you what happens</p> <pre><code>if #blocks &lt;= height then -- say #blocks is 3, height is 4 if #blocks[h] &lt;= length then -- E: in iteration 4 blocks[h] is nil if #blocks[h][y] &lt;= width then -- E: in it. 3,4 blocks[h][y] is nil num = blocks[h][y][x] end end end </code></pre> <p>You would have to test against nil on every level first, like</p> <pre><code>if blocks[h] and blocks[h][y] and blocks[h][y][x] and #blocks[h]&lt;=height and #blocks[h][y]&lt;=height and #blocks[h][y][x]&lt;=height num = blocks[h][y][x] end </code></pre> <h2>General programming mistakes</h2> <p><strong><code>blocks</code></strong>, <strong><code>length</code></strong>, <strong><code>width</code></strong> and <strong><code>height</code></strong> seem to be parameters for your function but are not in its header, so I suppose you set them externally before calling the function? This is certainly not good practice.</p> <p><strong><code>temp</code></strong> and <strong><code>num</code></strong> should be declared <code>local</code>.</p> <h2>Alternative</h2> <p>You can make the data-structure more intelligent, for example, if you put your 3D array in a flattened table and add a <code>__call</code> metamethod like this</p> <pre><code>function newMdArray(X, Y, Z) local MT = { __call = function(t, x, y, z, v) if x&gt;X or y&gt;Y or z&gt;Z or x&lt;1 or y&lt;1 or z&lt;1 then return nil end local k = x + X*(y-1) + X*Y*(z-1); if v ~= nil then t[k] = v; end return t[k] end }; return setmetatable({}, MT); end </code></pre> <p>Then this is all you have to do to make a resized copy of it:</p> <pre><code>function resizeMdArray(array, X, Y, Z) local r = newMdArray(X, Y, Z); for x=1, X do for y=1, Y do for z=1, Z do r(x, y, z, array(x, y, z) or 16); end end end return r; end </code></pre> <p>A nice bonus is, since this data structure flattens the 3D array into a 1D array, if you only want to <em>copy</em> the data, you can do so by simply accessing it as a table and copying each element:</p> <pre><code>for i=1, X*Y*Z do new[i] = old[i] end </code></pre> <p>Of course you could do the very same with a "real" (hidden) 3-D array in the background saving you the arithmetic calculations, however then you would have to test for empty values all the time to prevent nil errors.</p>
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    1. COMmm, this is a little bit more in depth than I expected to get... I get what your doing with it, it works but I got a fix which is a lot less complicated. Thanks tho
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    2. COOh, this was a while ago... But I don't think I saw your answer. Though I think this solution is a lot less complicated *to use*, as you don't have to "manually" test for `nil` whenever you want to access the data. But it's your decision of course.
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