MATLAB: How can assign aliases to column names in a dataset array in the Statistics Toolbox 7.1 (R2009a)

accessaliascolumndatasetdynamicmodifyStatistics and Machine Learning Toolboxstructure

I want to know if there is a way to alias the column names in a dataset array.

For example, if I have a dataset with column names:

 DataSheet.ScoreF
 DataSheet.ScoreK

When addressing these columns it would be nice to compactly address these columns:

for k = 1:NumCols
DataSheet.k = -1
end

rather than

DataSheet.ScoreF = -1;
DataSheet.ScoreK = -1;

This would lead to large savings as I have 100 columns to access and modify.

Best Answer

The example below demonstrates how to achieve the desired functionality. In the example, after the dataset is created, its column names are stored in a variable. The column names can then be used to dynamically access/modify the data in the dataset as follows:

load fisheriris
NumObs = size(meas,1);
NameObs = strcat({'Obs'},num2str((1:NumObs)','%d'));
iris = dataset({meas,'SL','SW','PL','PW'},...
      'ObsNames',NameObs);
h1 = iris.Properties.VarNames; %get column names and assign them to a variable
for i = 1:size(h1,2)
      iris.(h1{i}) = -1*ones(150,1); 
end

Related Solutions

MATLAB: Is it possible to check whether a column exists in a DATASET array

To check whether a column exists in a dataset array, one can query the variable names and use string comparison on the result. For example,

%%Create Dataset Array
load fisheriris
NumObs = size(meas,1);
NameObs = strcat({'Obs'},num2str((1:NumObs)','%-d'));
iris = dataset({nominal(species),'species'},...
                 {meas,'SL','SW','PL','PW'},...
                 'ObsNames',NameObs);
%%Check if column exists
strmatch('SL',get(iris,'VarNames'))

MATLAB: How to change the variable or observation names in the DATASET object in MATLAB 7.9 (R2009b)

DATASET objects have SET and GET methods defined. Please see the documentation for DATASET SET and GET methods for more information on usage.

Please also note that these methods are similar to the SET and GET methods defined for handle graphics, except for one important difference: to make a change on object OBJ, the object output from a SET command on OBJ must be reassigned to OBJ. If this reassignment is not done, the changes will not be made.

An example of changing the variable names of a dataset object for the IRIS object created above is as follows:

iris = set(iris,'VarNames',{'varname1','varname2','varname3','varname4','varname5'})

As per the reassignment discussion above, if we had executed the following, the changes would not have been made:

set(iris,'VarNames',{'varname1','varname2','varname3','varname4','varname5'})

To change only a single variable name, execute:

varnames = get(iris, 'VarNames');
varnames{3} = 'MyVarName';
iris = set(iris, 'VarNames', varnames);

You can also change a single variable name by explicitly setting this property, i.e.:

iris.Properties.VarNames{1}='newName'

Best Answer

Related Solutions

MATLAB: Is it possible to check whether a column exists in a DATASET array

MATLAB: How to change the variable or observation names in the DATASET object in MATLAB 7.9 (R2009b)

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