update readme

Author: AntSimi

README.md

@@ -6,20 +6,71 @@ To avoid problems with installation, use of the virtualenv Python virtual enviro
 
 Then use pip to install all dependencies (numpy, scipy, matplotlib, netCDF4, cython, pyproj, Shapely, ...), e.g.:
 
-* ** pip install cython numpy matplotlib scipy netCDF4 shapely pyproj**
+```bash
+pip install cython numpy matplotlib scipy netCDF4 shapely pyproj
+```
 
 Then run the following to install the eddy tracker:
 
-* ** python setup.py install**
+```bash
+python setup.py install
+```
 
 Two executables are now available in your PATH: EddyIdentification and EddyTracking
 
 Edit the corresponding yaml files and then run the code, e.g.:
 
-* ** EddyIdentification eddy_identification.yaml**
+```bash
+EddyIdentification eddy_identification.yaml
+```
 
 for identification, followed by:
 
-* ** EddyTracking tracking.yaml**
+```bash
+EddyTracking tracking.yaml
+```
+
+for tracking.
+
+
+# Py Eddy Tracker module #
+
+### Grid manipulation ###
+
+Loading grid
+```python
+from py_eddy_tracker.dataset.grid import RegularGridDataset
+h = RegularGridDataset('share/nrt_global_allsat_phy_l4_20190223_20190226.nc', 'longitude', 'latitude')
+```
+
+Plotting grid
+```python
+fig = plt.figure(figsize=(14, 12))
+ax = fig.add_axes([.02, .51, .9, .45])
+ax.set_title('ADT (m)')
+ax.set_ylim(-75, 75)
+ax.set_aspect('equal')
+m=ax.pcolormesh(h.x_bounds, h.y_bounds, h.grid('adt').T.copy(), vmin=-1, vmax=1, cmap='coolwarm')
+ax.grid(True)
+plt.colorbar(m, cax=fig.add_axes([.94, .51, .01, .45]))
+```
+
+Filtering
+```python
+h.bessel_high_filter('adt', 500, order=3)
+```
+
+Add second plot
+```python
+ax = fig.add_axes([.03, .02, .9, .45])
+ax.set_title('ADT Filtered (m)')
+ax.set_aspect('equal')
+ax.set_ylim(-75, 75)
+m=ax.pcolormesh(h.x_bounds, h.y_bounds, h.grid('adt').T, vmin=-.1, vmax=.1, cmap='coolwarm')
+ax.grid(True)
+plt.colorbar(m, cax=fig.add_axes([.94, .02, .01, .45]))
+fig.savefig('share/png/filter.png')
+```
+
+![signal filtering](share/png/filter.png)
 
-for tracking.