Replace array elements with strings

Question

Tim Richter 2021-11-5

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编辑： Jon 2021-11-5

Hello,

I constructed an array out of three column vectors: Col1, Col2, v.

These Vectors are always equal in length, but the overall length can vary. Col1 and Col2 contain positive intergers 1 to 36, v is a double -1 to 1. The complete array displays corrolations between Polynomials, e.g: 1 (Col1 Index 1) and 3 (Col2 Index 1) corrolate with a value of -0.5 (v Index 1).

Since the Integers 1 to 36 identify the "Type" of a Zernike Polynomial, i want to replace them with the actual name of the Polynomial.

1 is called "Piston"

2 is called "Tilt X"

and so on .

In my array, or in the vectors, how can i change an integer element to a string, depending on it's value?

Thanks in advance!

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Answer 1

Jon 2021-11-5

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编辑：Jon 2021-11-5

在 MATLAB Online 中打开

In the example code below I show how to do it with 4 names, but you can expand it to however many names you have.

names = {'Piston','Tilt X', 'someName', 'yetAnotherName'}
Col1 = [1;3;4;2;1;4;3]
Col2 = [2;3;1;4;2;2;3]
v = [-0.9; 0.8; 0.2; -0.8;0.1;0.3;-0.2]
% put columns into a matrix
M = [Col1 Col2 v]
% substitute names based on indices
MwithNames = {names(Col1)' names(Col2)' v}

>> MwithNames{:,1}

ans =

7×1 cell array

{'Piston' }

{'someName' }

{'yetAnotherName'}

{'Tilt X' }

{'Piston' }

{'yetAnotherName'}

{'someName' }

>> MwithNames{:,2}

ans =

7×1 cell array

{'Tilt X' }

{'someName' }

{'Piston' }

{'yetAnotherName'}

{'Tilt X' }

{'someName' }

>> MwithNames{:,3}

ans =

-0.9000

0.8000

0.2000

-0.8000

0.1000

0.3000

-0.2000

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Tim Richter 2021-11-5

Thank you very much! Didn't think it was that easy.

Jon 2021-11-5

编辑：Jon 2021-11-5

I think the data is acually in the array you call Output but it is a little hard to see. You can drill down in the workspace tab in your MATLAB IDE, or by looking at them individually, e.g typing Output{:,1} on the command line.

In any case as @Steven Lord suggested, it is probably nicer to put the mixed data (character and numeric) in a table as Ishow in my second example above

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Answer 2

Steven Lord 2021-11-5

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I recommend using a table array to store your data of mixed types.

load patients
T = table(LastName, Age, Smoker);
head(T) % Display just the first few rows of T
ans = 8×3 table
      LastName      Age    Smoker
    ____________    ___    ______

    {'Smith'   }    38     true  
    {'Johnson' }    43     false 
    {'Williams'}    38     false 
    {'Jones'   }    40     false 
    {'Brown'   }    49     false 
    {'Davis'   }    46     false 
    {'Miller'  }    33     true  
    {'Wilson'  }    40     false 