Can I pass table as an argument to a function.?
34 views (last 30 days)
Show older comments
Hi,
Currently I am working on migration of MATLAB scripts to C++ code.
I encountered a problem with the datastucture table. Basically I am reading a CSV file using readtable and stored it in a table DataTable. I want to send this table to a function which uses the DataTable for some calculations. But when I tried to access the members of the DataTable this is where the problem starts, The coder app is not allowing me to access the parameters in the DataTable and is showing the error "When indexing a table using variable names, the names of the table variables must be constant.". Example code is below
mycsv.csv is a simple csv file with feilds as X and Y
X,Y
1011,203
1026,210
DataTable = readtable("mycsv.csv");
MyCalulations(DataTable);
function MyCalulations(DataTable)
Xmean=mean(DataTable.X);
Ymean=mean(DataTable.Y)
end
0 Comments
Accepted Answer
Ameer Hamza
on 22 Sep 2020
Edited: Ameer Hamza
on 22 Sep 2020
See this answer here: https://www.mathworks.com/matlabcentral/answers/572815-matlab-coder-table-variables-must-be-constant. It will be easier if you index the table using numeric values. For example
function MyCalulations(DataTable)
Xmean=mean(DataTable{:,1});
Ymean=mean(DataTable{:,2})
end
The C++ code is generated correctly.
These are some useful links:
0 Comments
More Answers (1)
Image Analyst
on 22 Sep 2020
Can you attach "mycsv.csv" so we can try it? It might call the fields "Var1" and "Var2" instead of X and Y since you didn't specify field names for the table.
4 Comments
Image Analyst
on 22 Sep 2020
Edited: Image Analyst
on 22 Sep 2020
I don't have the Coder Toolbox like you do, so I can't help. Sorry. Contact tech support.
By the way, this works if you set ReadVariableNames to true:
DataTable = readtable("mycsv.csv", 'ReadVariableNames', true)
MyCalculations(DataTable)
function [Xmean, Ymean] = MyCalculations(DataTable)
Xmean = mean(DataTable.X)
Ymean = mean(DataTable.Y)
end
Ameer Hamza
on 22 Sep 2020
For me, even this works fine
DataTable = readtable("mycsv.csv")
MATLAB automatically read the variable name. I am using R2020a. Maybe this behaviour was changed in some recent release.
See Also
Categories
Find more on Logical in Help Center and File Exchange
Products
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!