preallocating大阵在MATLAB matfile比其他零东西 [英] Preallocating a large array in a MATLAB matfile with something other than zeroes

问题描述

我需要编写一个数组，它是太大，无法到内存到.MAT二进制文件。这可以通过 matfile 命令，该命令允许在光盘上。

I need to write an array that is too large to fit into memory to a .mat binary file. This can be accomplished with the matfile command, which allows random access to a .mat file on disc.

我试图preallocate阵列中的这个文件，并通过的 MathWorks公司博客是

I am trying to preallocate the array in this file, and the approach recommended by a MathWorks blog is

matObj = matfile('myBigData.mat','Writable',true); 
matObj.X(10000,10000) = 0;

这工作，但给我留下了一个大阵零 - 这是有风险的，因为一些我将与填充它真正的价值也可能是零。对于较小的阵列，我通常会做的。

This works, but leaves me with a large array of zeroes - which is risky, as some of the genuine values that I will be populating it with may also be zero. For smaller arrays, I would typically do

smallarray = nan(20,20);

但是，如果我尝试这种方法的大阵，我得到一个内存不足的错误; presumably的楠（）功能是生产大阵 NaN的 S IN内存首。

But if I try this approach for the large array I get an "out of memory" error; presumably the nan() function is producing the large array of NaNs in memory first.

如何preallocate大阵比其他零东西？

推荐答案

这方法对我的作品。请注意，您必须指定矩阵索引的范围内（ X（1：10000,1：） 10000），否则你刚才设置的单一元素在 10000,10000 到 NaN的。

This method works for me. Note that you have to specify the range for the matrix index (X(1:10000,1:10000)), otherwise you just set the single element at 10000,10000 to NaN.

matObj = matfile('myBigData.mat','Writable',true); 
matObj.X(1:10000,1:10000) = NaN;

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