Computes correlation matrix of columns
        :return: Correlation matrix of columns

def get_correlation_matrix_from_columns(self):
        """Computes correlation matrix of columns
        :return: Correlation matrix of columns
        """
        header_to_column = {}  # create index of headers
        for header in self.headers:
            header_to_column[header] = self.headers.index(header)

        data_to_test = []
        for header in self.headers_to_test:
            header_column = Matrix(self.data) \
                .get_column(header_to_column[header])

            for i, value in enumerate(header_column):
                header_column[i] = float(value)  # get float

            data_to_test.append(header_column)

        return self.get_correlation_matrix(data_to_test)