How do I generate executable code from imported data?

2023 11 27
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更新时间：2023 11 29
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I have an xlsx file with various data for the calculation I'd like to conduct with my Matlab code. This file also contains the relevant formulas. Is there a way to import those formulas from xlsx (having them as a string) and convert them to normal code thats executable?

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Dyuman Joshi
Dyuman Joshi 2023-11-27
编辑：Dyuman Joshi 2023-11-28
Can it be done? Yes. Is it recommended? No.
Though, you could define the formulae in the syntax of function handles and utilize str2func to convert them to anonymous functions, and use accordingly.
Johannes
Johannes 2023-11-27
That is a good approach, thank you. However, the str2func command does not accept variables from outside the function. As I have pre-defined variables, there is an issue with the function
Dyuman Joshi
Dyuman Joshi 2023-11-27
Can you show what the formulas look like? It will even better if you could attach the excel file.
Johannes
Johannes 2023-11-27
编辑：Johannes 2023-11-27
I made a test script for the function. My minimum code example looks like this:
clear all
close all
clc
Flushmatrix = readtable('Spülmatrix2.xlsx','PreserveVariableNames',true);
%%
psat = 1.5;
p_fmin = psat+1;
v = 330;
%%
a = Flushmatrix(1,9);
a = string(table2cell(a));
%%
fh = str2func(a)
fh(v, psat, p_fmin)
The xlsx file contains the variables and functions. I attached it to this comment. The problem is that the function is not callable like this. If I try to run it with my preset variables, it gives this error:
Undefined function
'((table2array(Flushmatrix(1,3))*(v/1000)+table2array(Flushmatrix(1,4)))*log(psat)+(table2array(Flushmatrix(1,5))*v+table2array(Flushmatrix(1,6))))/1000'
for input arguments of type 'double'.
Error in str2func_Test (line 16)
fh(v, psat, p_fmin)
Dyuman Joshi
Dyuman Joshi 2023-11-27
Sorry, I was away from my PC due to some other work. Please check my answer below.

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Dyuman Joshi
Dyuman Joshi 2023-11-27
Ran in:

1 个投票

Ran in:
You need to add the @(list_of_independent_variables) before the formulae.
Flushmatrix = readtable('Spülmatrix2.xlsx','PreserveVariableNames',true)
Flushmatrix = 3×9 table
Spülen Produkt K1 [s/mL] K2 [s] K3 [s/mL] K4 [s] K5 K6 Funktion ____________ ________ _________ _________ _________ ________ _____ ____ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ {'standard'} {'Bier'} -0.23643 -0.040387 0.7205 0.039548 NaN NaN {'@(Flushmatrix, v, psat) ((table2array(Flushmatrix(1,3))*(v/1000)+table2array(Flushmatrix(1,4)))*log(psat)+(table2array(Flushmatrix(1,5))*v+table2array(Flushmatrix(1,6))))/1000'' } {'standard'} {'CSD' } -0.17236 -0.038639 0.47643 0.037187 NaN NaN {'@(Flushmatrix, v, psat) ((table2array(Flushmatrix(2,3))*(v/1000)+table2array(Flushmatrix(2,4)))*log(psat)+(table2array(Flushmatrix(2,5))*v+table2array(Flushmatrix(2,6))))/1000'' } {'sanft' } {'Bier'} 175.4 -1666 -345.6 3823 3.032 -305 {'@(Flushmatrix, v, psat, p_fmin) ((table2array(Flushmatrix(3,3))*p_fmin+table2array(Flushmatrix(3,4)))*(v/1000)^2+(table2array(Flushmatrix(3,5))*p_fmin+table2array(Flushmatrix(3,6)))*(v/1000)+(table2array(Flushmatrix(3,7))*p_fmin+table2array(Flushmatrix(3,8))))/1000'}
%values for variables
psat = 1.5;
p_fmin = psat+1;
v = 330;
%Value from the formula copied and pasted
((table2array(Flushmatrix(1,3))*(v/1000)+table2array(Flushmatrix(1,4)))*log(psat)+(table2array(Flushmatrix(1,5))*v+table2array(Flushmatrix(1,6))))/1000
ans = 0.2378
%formula from the table read
a = Flushmatrix(1,9);
a = string(table2cell(a))
a = "@(Flushmatrix, v, psat) ((table2array(Flushmatrix(1,3))*(v/1000)+table2array(Flushmatrix(1,4)))*log(psat)+(table2array(Flushmatrix(1,5))*v+table2array(Flushmatrix(1,6))))/1000'"
%convert the string to a function handle
fh = str2func(a)
fh = function_handle with value:
@(Flushmatrix,v,psat)((table2array(Flushmatrix(1,3))*(v/1000)+table2array(Flushmatrix(1,4)))*log(psat)+(table2array(Flushmatrix(1,5))*v+table2array(Flushmatrix(1,6))))/1000'
%corresponding value
fh(Flushmatrix, v, psat)
ans = 0.2378

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Dyuman Joshi
Dyuman Joshi 2023-11-27
Though, I am wondering, can't you just copy and paste the formulas from the excel file to MATLAB?
Johannes
Johannes 2023-11-28
Thank you so much for the help. We are working with the Matlab App Designer, so in the long term this could maybe be implemented in an app. There might be users with no Matlab license, so it`s more convenient to just change the xlsx file when one needs to change the formulae or coefficients.
Dyuman Joshi
Dyuman Joshi 2023-11-29
I see.
Also, you can modify this lines -
a = Flushmatrix(1,9);
a = string(table2cell(a));
fh = str2func(a);
to
fh = str2func(Flushmatrix{1,9})
For more info - Access Data in Tables

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