remove print from tree use __str__

Author: Licini

src/compas/datastructures/tree/tree.py

@@ -244,12 +244,11 @@ class Tree(Datastructure):
     >>> branch.add(leaf1)
     >>> branch.add(leaf2)
     >>> print(tree)
-    <Tree with 4 nodes, 1 branches, and 2 leaves>
-    >>> tree.print()
-    <TreeNode root>
-        <TreeNode branch>
-            <TreeNode leaf2>
-            <TreeNode leaf1>
+    <Tree with 4 nodes>
+    |--<TreeNode: root>
+        |-- <TreeNode: branch>
+            |-- <TreeNode: leaf1>
+            |-- <TreeNode: leaf2>
 
     """
 
@@ -281,6 +280,9 @@ def __init__(self, name=None, **kwargs):
         super(Tree, self).__init__(kwargs, name=name)
         self._root = None
 
+    def __str__(self):
+        return "<Tree with {} nodes>\n{}".format(len(list(self.nodes)), self.hierarchy(max_depth=3))
+
     @property
     def root(self):
         return self._root
@@ -435,12 +437,9 @@ def get_nodes_by_name(self, name):
                 nodes.append(node)
         return nodes
 
-    def __repr__(self):
-        return "<Tree with {} nodes>".format(len(list(self.nodes)))
-
-    def print_hierarchy(self, max_depth=None):
+    def hierarchy(self, max_depth=None):
         """
-        Print the spatial hierarchy of the tree.
+        Return string for the spatial hierarchy of the tree.
 
         Parameters
         ----------
@@ -450,22 +449,27 @@ def print_hierarchy(self, max_depth=None):
 
         Returns
         -------
-        None
+        str
+            The spatial hierarchy of the tree.
 
         """
 
-        def _print(node, prefix="", last=True, depth=0):
+        hierarchy = {"string": ""}
+
+        def traverse(node, hierarchy, prefix="", last=True, depth=0):
 
             if max_depth is not None and depth > max_depth:
                 return
 
             connector = "└── " if last else "├── "
-            print("{}{}{}".format(prefix, connector, node))
+            hierarchy["string"] += "{}{}{}\n".format(prefix, connector, node)
             prefix += "    " if last else "│   "
             for i, child in enumerate(node.children):
-                _print(child, prefix, i == len(node.children) - 1, depth + 1)
+                traverse(child, hierarchy, prefix, i == len(node.children) - 1, depth + 1)
+
+        traverse(self.root, hierarchy)
 
-        _print(self.root)
+        return hierarchy["string"]
 
     def to_graph(self, key_mapper=None):
         """Convert the tree to a graph.