fix py2 and update readme

README.md

@@ -4,27 +4,27 @@
 
 ## Sea ice drift from Sentinel-1 SAR data
 
-A computationally efficient, open source feature tracking algorithm, 
+A computationally efficient, open source feature tracking algorithm,
 called ORB, is adopted and tuned for retrieval of the first guess
-sea ice drift from Sentinel-1 SAR images. Pattern matching algorithm 
+sea ice drift from Sentinel-1 SAR images. Pattern matching algorithm
 based on MCC calculation is used further to retrieve sea ice drift on a
 regular grid.
 
 ## References:
  * Korosov A.A. and Rampal P., A Combination of Feature Tracking and Pattern Matching with Optimal Parametrization for Sea Ice Drift Retrieval from SAR Data, Remote Sens. 2017, 9(3), 258; [doi:10.3390/rs9030258](http://www.mdpi.com/2072-4292/9/3/258)
  * Muckenhuber S., Korosov A.A., and Sandven S., Open-source feature-tracking algorithm for sea ice drift retrieval from Sentinel-1 SAR imagery, The Cryosphere, 10, 913-925, [doi:10.5194/tc-10-913-2016](http://www.the-cryosphere.net/10/913/2016/), 2016
- 
+
 ## Requirements:
  * [Nansat](https://github.com/nansencenter/nansat) - scientist friendly open-source Python toolbox for processing 2D satellite earth observation data)
  * [OpenCV](http://opencv.org) - open-source computer vision
 
 ## Installation
- * Install Nansat as described on the [home page](https://github.com/nansencenter/nansat)
- * Install OpenCV (e.g. using [miniconda](http://conda.pydata.org/miniconda.html): `conda install -c conda-forge opencv`
+  * Install Python, OpenCV and other requirements using [miniconda](http://conda.pydata.org/miniconda.html):
+    `conda create -q --yes -n py3drift -c conda-forge python=3.6 numpy scipy matplotlib netcdf4 gdal opencv nose`
+  * Activate the environment:
+    `source activate py3drift`
  * Use pip to install from the repo:
-```
-pip install https://github.com/nansencenter/sea_ice_drift/archive/v0.5.tar.gz
-```
+    `pip install https://github.com/nansencenter/sea_ice_drift/archive/v0.7.tar.gz`
 
 ## Example
 ```

sea_ice_drift/pmlib.py

@@ -12,6 +12,8 @@
 # This program is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+from __future__ import absolute_import, print_function
+
 import time
 from multiprocessing import Pool