'polymer peak 0 (N)', 'polymer peak 1 (N)', 'polymer peak 2 (N)',
'polymer peak 3 (N)', 'polymer peak 4 (N)', 'polymer peak 5 (N)']
>>> retract[:5,-2:]
-Data([[ NaN, NaN],
- [ NaN, NaN],
- [ NaN, NaN],
- [ NaN, NaN],
- [ NaN, NaN]])
+Data([[ nan, nan],
+ [ nan, nan],
+ [ nan, nan],
+ [ nan, nan],
+ [ nan, nan]])
>>> retract[1097:1103,-2:] # doctest: +ELLIPSIS
-Data([[ NaN, 5.2...e-10],
- [ NaN, 5...e-10],
- [ NaN, 6.1...e-10],
- [ NaN, 6.2...e-10],
- [ NaN, 7...e-10],
- [ NaN, NaN]])
+Data([[ nan, 5.2...e-10],
+ [ nan, 5...e-10],
+ [ nan, 6.1...e-10],
+ [ nan, 6.2...e-10],
+ [ nan, 7...e-10],
+ [ nan, nan]])
>>> retract[-5:,-2:]
-Data([[ NaN, NaN],
- [ NaN, NaN],
- [ NaN, NaN],
- [ NaN, NaN],
- [ NaN, NaN]])
+Data([[ nan, nan],
+ [ nan, nan],
+ [ nan, nan],
+ [ nan, nan],
+ [ nan, nan]])
"""