From a250f985e3b9d78f6375febf02ba1c5cc14b50c2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Llu=C3=ADs=20Vilanova?= <vilanova@ac.upc.edu>
Date: Tue, 7 Sep 2010 15:26:05 +0200
Subject: [PATCH] Make 'DataArray.labels' a property calculated on-demand
 (closes fperez/datarray#26).

The current implementation calculates the result on every query, as 'labels' is
not used very often.
---
 datarray/datarray.py | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/datarray/datarray.py b/datarray/datarray.py
index e83971b..4a6aa8c 100644
--- a/datarray/datarray.py
+++ b/datarray/datarray.py
@@ -460,7 +460,6 @@ def _set_axes(dest, in_axes):
 
     - axis: a KeyStruct with each axis as a named attribute.
     - axes: a list of all axis instances.
-    - labels: a list of all the axis labels.
 
     Parameters
     ----------
@@ -470,7 +469,6 @@ def _set_axes(dest, in_axes):
     # XXX: This method is called multiple times during a DataArray's lifetime.
     #      Should rethink exactly when Axis copies need to be made
     axes = []
-    labels = []
     ax_holder = KeyStruct()
     # Create the containers for various axis-related info
     for ax in in_axes:
@@ -481,11 +479,9 @@ def _set_axes(dest, in_axes):
                 'There is another Axis in this group with ' \
                 'the same name'
                 )
-        labels.append(ax.label)
         ax_holder[ax.name] = new_ax
     # Store these containers as attributes of the destination array
     dest.axes = tuple(axes)
-    dest.labels = tuple(labels)
     dest.axis = ax_holder
     
 
@@ -621,6 +617,11 @@ def aix(self):
     def set_label(self, i, label):
         self.axes[i].set_label(label)
 
+    @property
+    def labels (self):
+        """Returns a tuple with all the axis labels."""
+        return tuple((ax.label for ax in self.axes))
+
     def __array_finalize__(self, obj):
         """Called by ndarray on subobject (like views/slices) creation.