Constructs the term doc matrix.

		Returns
		-------
		scattertext.ParsedCorpus.ParsedCorpus

def build(self):
		'''Constructs the term doc matrix.

		Returns
		-------
		scattertext.ParsedCorpus.ParsedCorpus
		'''
		self._y = self._get_y_and_populate_category_idx_store()
		self._df.apply(self._add_to_x_factory, axis=1)
		self._X = self._X_factory.set_last_row_idx(len(self._y)-1).get_csr_matrix()
		self._mX = self._mX_factory.set_last_row_idx(len(self._y)-1).get_csr_matrix()
		return ParsedCorpus(self._df,
		                    self._X,
		                    self._mX,
		                    self._y,
		                    self._term_idx_store,
		                    self._category_idx_store,
		                    self._metadata_idx_store,
		                    self._parsed_col,
		                    self._category_col)