Initial commit

python/Math/Parse math formulas and put parentheses around multiplication and division.py

@@ -0,0 +1,47 @@
+#https://gist.github.com/ohaz/ed0b14a487b0569aad2d  
+import ast  
+  
+def recurse(node):  
+    if isinstance(node, ast.BinOp):  
+        if isinstance(node.op, ast.Mult) or isinstance(node.op, ast.Div):  
+            print('(', end='')  
+        recurse(node.left)  
+        recurse(node.op)  
+        recurse(node.right)  
+        if isinstance(node.op, ast.Mult) or isinstance(node.op, ast.Div):  
+            print(')', end='')  
+    elif isinstance(node, ast.Add):  
+        print('+', end='')  
+    elif isinstance(node, ast.Sub):  
+        print('-', end='')  
+    elif isinstance(node, ast.Mult):  
+        print('*', end='')  
+    elif isinstance(node, ast.Div):  
+        print('/', end='')  
+    elif isinstance(node, ast.Num):  
+        print(node.n, end='')  
+    else:  
+        for child in ast.iter_child_nodes(node):  
+            recurse(child)  
+  
+  
+def search_expr(node):  
+    returns = []  
+    for child in ast.iter_child_nodes(node):  
+        if isinstance(child, ast.Expr):  
+            return child  
+        returns.append(search_expr(child))  
+    for ret in returns:  
+        if isinstance(ret, ast.Expr):  
+            return ret  
+    return None  
+  
+  
+formula = '4+5*7/2'  
+  
+a = ast.parse(formula)  
+  
+expr = search_expr(a)  
+if expr is not None:  
+    recurse(expr)  
+print()