>>> approach.info['columns']
['z piezo (m)', 'deflection (m)', 'flattened deflection (m)']
>>> approach[:5,-1] # doctest: +ELLIPSIS
-Data([ 9.094...e-08, 9.130...e-08, 9.157...e-08,
- 9.189...e-08, 9.221...e-08])
+Data([ -3.603...e-08, -3.566...e-08, -3.539...e-08,
+ -3.508...e-08, -3.476...e-08])
>>> approach[-5:,-1] # doctest: +ELLIPSIS
Data([ 3.624...e-10, 5.884...e-10, 2.257...e-10,
-9.157...e-11, -9.027...e-13])