Matlab turns char into double on cluster.

Question

Michael Stollenwerk 2022-3-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1684084-matlab-turns-char-into-double-on-cluster

评论： Stephen23 2022-4-5

采纳的回答： Voss

在 MATLAB Online 中打开

On the cluster I run

matlab -nodesktop -r "program 1" > program_1.out 2>&1

where the first lines of code in "program" look like this

function program(dtaset_id)
addpath(genpath('../..'))
if isempty(gcp('nocreate'))
    parpool(maxNumCompThreads,'IdleTimeout', 300)
end
whos
load(strcat('dataset_', dtaset_id, '.mat'))
whos
dtaset_id = str2num(dtaset_id);

The strange thing is that the first "whos" reports "dtaset_id" to be a char, and the second whos reports it to be a double, causing an error in the last line.

How and why does this happen?

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Answer 1

Voss 2022-3-30

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1684084-matlab-turns-char-into-double-on-cluster#answer_930599

在 MATLAB Online 中打开

dataset_0.mat

It may be that the mat file you load contains a variable called dtaset_id, which is a double. When you load the mat file that value overwrites the previous value of dtaset_id in your workspace.

Here I've attached a mat file with a double dtaset_id to demonstrate.

dtaset_id = '0';
whos('dtaset_id') % char
  Name           Size            Bytes  Class    Attributes

  dtaset_id      1x1                 2  char               
load(strcat('dataset_', dtaset_id, '.mat')) % overwrites dtaset_id with value from mat file
whos('dtaset_id') % now double
  Name           Size            Bytes  Class     Attributes

  dtaset_id      1x1                 8  double              