[example] update

examples/formula/formula.py

@@ -1,13 +1,36 @@
 # coding: utf-8
 # 2021/3/8 @ tongshiwei
+#
+from EduNLP.Formula import Formula, FormulaGroup, link_formulas
+#
+# f1 = Formula(r"x + y", variable_standardization=True)
+# f2 = Formula(r"y + x", variable_standardization=True)
+# f3 = Formula(r"z + y", variable_standardization=True)
+#
+# print(f1.element)
+# print(f2.element)
+# print(f3.element)
+#
+# print("-----------------------")
+#
+# link_formulas(f1, f2, f3)
+#
+# print("------------------------")
+#
+# print(f1.element)
+# print(f2.element)
+# print(f3.element)
+#
+# print("---------------------")
+#
+# fg = FormulaGroup(
+#     [r"x + y", r"y + x", r"y + z"]
+# )
+# for f in fg:
+#     print(f.element)
 
-import matplotlib.pyplot as plt
-from EduNLP.Formula import Formula
-from EduNLP.Formula.viz import ForestPlotter
+# fg = FormulaGroup(["x", "y", "x"])
+# print(fg.elements)
 
-f = Formula(r"\frac{\sqrt{x^2}}{\pi} + 1 = y", variable_standardization=True)
-
-ForestPlotter().export(
-    f.ast, root_list=[node["val"]["id"] for node in f.element if node["structure"]["father"] is None],
-)
-plt.show()
+fg = FormulaGroup(["x", Formula("y"), "x"])
+print(fg.elements)