MATLAB: How to create and store a matrix from a dataset comprising of certain rows from the dataset.

datasetMATLABmatrix

Need to create a matrix from a dataset that selects certain rows depending on whether a given condition is fulfilled. For eg, from the IRIS dataset, create a matrix comprising of first 30 samples for each class.

Best Answer

load iris.dat               
setosa = iris((iris(:,5)==1),:);        % data for setosa
versicolor = iris((iris(:,5)==2),:);    % data for versicolor
virginica = iris((iris(:,5)==3),:);     % data for virginica
obsv_n = size(iris, 1);                 % total number of observations

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MATLAB: How to compare non numerical values or character strings element-wise between a table and a one dimensional array

https://in.mathworks.com/matlabcentral/answers/450866-how-to-compare-non-numerical-values-or-character-strings-element-wise-between-a-table-and-a-one-dime#comment_682761

MATLAB: Unrecognized function or variable ‘carsmall’

This is not a question of you updating your version. I can see what you did, but not what you were hoping to do. Suppose I try this:

load randomstuff.mat
Error using load
Unable to read file 'randomstuff.mat'. No such file or directory.

So, if I try loading a file that does not exist, it gives me an error, telling me the file does not exist, but NOT what you got.

What did you get?

Unrecognized function or variable 'carsmall'.
Error in Exercise_3_1 (line 8)
gplotmatrix(carsmall);

That tells me the load did work, but there is no variable named carsmall in that .mat file.

I would suggest you try this:

load carsmall.mat;
whos
  Name                Size            Bytes  Class     Attributes
  Acceleration      100x1               800  double              
  Cylinders         100x1               800  double              
  Displacement      100x1               800  double              
  Horsepower        100x1               800  double              
  MPG               100x1               800  double              
  Mfg               100x13             2600  char                
  Model             100x33             6600  char                
  Model_Year        100x1               800  double              
  Origin            100x7              1400  char                
  Weight            100x1               800  double

So there is indeed no variable by that name in the .mat file. Lots of other stuff, but not carsmall. What you want to do next is up to you.

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MATLAB: How to compare non numerical values or character strings element-wise between a table and a one dimensional array

MATLAB: Unrecognized function or variable ‘carsmall’

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