How do I convert table data to double to manipulate them?

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Fernando De Ita
Fernando De Ita 2017-12-2
编辑： Stephen23 2024-6-6
I extract data from a table. When I retrieve an element, it is in table format, but I encounter an error when attempting to perform operations like multiplication. Is there a direct command or a series of steps to address this issue?
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Stephen23
Stephen23 2021-8-25
编辑：Stephen23 2021-8-25
"I extracted data from a table, when I get an element it comes as table format but when trying to make some operations like multiplication there is an error, is there any direct command or a series of steps?"
You could use TABLE2ARRAY, but by far the simplest and most efficient approach is to just use the correct indexing using curly braces to access the table content (not parentheses which returns another table, which is what you did).
The different types of indexing are clearly explained in the documentation:
https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-table.html
Peter Perkins
Peter Perkins 2021-11-8
This new example goes even further into indexing and the topic of "doing math on data stored in a MATLAB table":
https://www.mathworks.com/help/matlab/matlab_prog/computations-with-numeric-data-in-table-or-timetable.html
It's a new-for-R2021b example, but doesn't require the latest MATLAB for anything (most anything?) it covers.

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采纳的回答

Star Strider
Star Strider 2024-9-4
编辑：MathWorks Support Team 2024-6-5
There are several ways you can convert or extract table data to an array. 
You can use dot notation or curly brace indexing, as described in the following documentation:
Access Data in Tables
https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-table.html
A = T.Variables% All table data concatenated into an array A = T{:,:}% All table data concatenated into an array A = T{rows,vars}% Specified rows and variables into an array
You can also use the "table2array" function. 
A = table2array(T)
And finally, there are many operations you can perform on table data without converting it at all. For examples, see the following documentation:
Direct Calculations on Tables and Timetables
https://www.mathworks.com/help/matlab/matlab_prog/direct-calculations-on-tables-and-timetables.html
Calculations When Tables Have Both Numeric and Nonnumeric Data
https://www.mathworks.com/help/matlab/matlab_prog/calculations-when-tables-have-both-numeric-and-nonnumeric-data.html
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Peter Perkins
Peter Perkins 2023-9-28
Ran in:
In recent versions of MATLAB, tables and timetables support many element+wise and reduction math operations:
t1 = table([1;2;3],[4;5;6]);
sum(t1,1)
ans = 1×2 table
Var1 Var2 ____ ____ 6 15
t2 = table([7;8;9],[10;11;12]);
t1 + t2
ans = 3×2 table
Var1 Var2 ____ ____ 8 14 10 16 12 18
For many other operations, see https://www.mathworks.com/help/matlab/matlab_prog/computations-with-numeric-data-in-table-or-timetable.html.

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更多回答（3 个）

Peter Perkins
Peter Perkins 2017-12-19
The answer might be as simple as something like T.Z = T.x .* T.y. Without more information, hard to tell.
Roger Breton
Roger Breton 2021-3-8
编辑：Roger Breton 2021-3-8
It does not work for me : all I want is to be able to import a range from Excel, and all I get is a "Table" on which I can't do any operation?
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Roger Breton
Roger Breton 2021-3-9
Thank you so much for extending your kind help, Peter.
Yes, all my data is numieric, doubles, in fact. It's just that I'm totally "green" with regards to MatLab data types. I think I used the table2array function to "convert" the data. Once converted, I was able to carry my "normal" arithmetic operation. I really have to give myself the time to learn Matlab...
Stephen23
Stephen23 2021-8-25
编辑：Stephen23 2024-6-6
If you just need a numeric matrix, why are you importing the data as a table? Use READMATRIX instead.

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Arshey Dhangekar
Arshey Dhangekar 2021-7-7
Hello I have csv data of 18 columns and want to convert into double
so instead of writing 18 str2double code how can I convert all the 18 columns in short line of code
Temp.x310_Ambient__C_ = str2double (Temp.x310_Ambient__C_);
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Mohsin Munir
Mohsin Munir 2021-8-25
I have data in excel. there are some coulmns having inputs. I want if i multiply two columns in matlab then the next column to be added in the same sheet rather than a new file in workspace. can anybody help me in this problem
Peter Perkins
Peter Perkins 2021-11-8
1) Post a new question, don't ask a question in a reply to someone else's question.
2) This example may be of help for the topic of "doing math on data stored in a MATLAB table":
https://www.mathworks.com/help/matlab/matlab_prog/computations-with-numeric-data-in-table-or-timetable.html
It's a new-for-R2021b example, but doesn't require the latest MATLAB for anything (most anything?) it covers.

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