transform method
Standardizes the data (zero mean, unit variance).
Implementation
List<List<double>> transform(List<List<double>> data) {
_checkFitted();
validate2DInput(data);
final numFeatures = _mean.length;
return data.map((row) {
return List.generate(numFeatures, (i) {
final std = _std[i];
if (std == 0) return 0.0;
return (row[i] - _mean[i]) / std;
});
}).toList();
}