Add data download info to README and set to gait cycle 0.

Author: moorepants

README.rst

@@ -34,6 +34,19 @@ Change back into the project repository::
 
    cd ../gait-closed-loop-id
 
+Data
+====
+
+There is sample data in the ``data/`` directory for tracking but you can use
+data we collected by downloading this `sample file
+<https://drive.google.com/file/d/1rsBbDih0fqa8v14fmY7__Ss01eaY7Ol9/view?usp=sharing>`_
+[16Mb], unzipping it, and placing the CSV file into the ``data/`` directory.
+This is sample data from trial 20 from:
+
+Moore JK, Hnat SK, van den Bogert AJ. 2015. An elaborate data set on human gait
+and the effect of mechanical perturbations. PeerJ 3:e918
+https://doi.org/10.7717/peerj.918
+
 Run
 ===
 

src/solve.py

@@ -37,7 +37,7 @@
 if os.path.exists(DATAPATH):
     # load a gait cycle from our data (trial 20)
     duration, walking_speed, num_angles, ang_data = load_sample_data(
-        num_nodes, gait_cycle_number=2)
+        num_nodes, gait_cycle_number=0)
 else:
     # load normal gait data from Winter's book
     duration, walking_speed, num_angles, ang_data = load_winter_data(num_nodes)