[whpalmer4]

It isn't too difficult to do manually, though it would be a bit tedious if you had a large number of graphs to do. Click on the first point to the left of your axis rectangle, then go to the inspector, scroll to the top and shift click at the beginning of the data. Press the delete key. That kills everything to the left. Similarly, for the unwanted data to the right, click on the first point outside the bounding box, bring up the inspector, scroll to the bottom, shift click on the end of the data, then press delete. No need to delete all those unwanted points one by one!