:orphan:

.. _trajectories:

Trajectories
************

Data stored in contiguous ragged array format, such as from Kevin Hodges's TRACK program, can be plotted using cf-plot.


Example 39 - basic track plotting
---------------------------------

.. image::  images/fig39.png
   :scale: 52%



::


   import cf
   import cfplot as cfp
   f=cf.read('cfplot_data/ff_trs_pos.nc')[0]
   cfp.traj(f)


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Here a plot of relative vorticity tracks is made in the cylindrical projection.


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Example 40 - tracks in the polar stereographic projection
---------------------------------------------------------

.. image::  images/fig40.png
   :scale: 52%



::


   import cf
   import cfplot as cfp
   f=cf.read('cfplot_data/ff_trs_pos.nc')[0]
   cfp.mapset(proj='npstere')
   cfp.traj(f)


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Example 41 - feature propagation over Europe
--------------------------------------------

.. image::  images/fig41.png
   :scale: 52%



::


   import cf
   import cfplot as cfp
   f=cf.read('cfplot_data/ff_trs_pos.nc')[0]
   cfp.mapset(lonmin=-20, lonmax=20, latmin=30, latmax=70)
   cfp.traj(f, vector=True, markersize=0.0, fc='b', ec='b')


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Data with lots of tracks takes several seconds to plot as the direction vectors have to be plotted individually whether
they are on the plot or not.



Example 42 - intensity legend
-----------------------------

.. image::  images/fig42.png
   :scale: 52%




::


   import cf
   import cfplot as cfp
   f=cf.read('cfplot_data/ff_trs_pos.nc')[0]
   cfp.mapset(lonmin=-50, lonmax=50, latmin=20, latmax=80)
   g=f.subspace(time=cf.wi(cf.dt('1979-12-01'), cf.dt('1979-12-10')))
   g=g*1e5
   cfp.levs(0, 12, 1, extend='max')
   cfp.cscale('scale1', below=0, above=13)
   cfp.traj(g, legend=True,  linewidth=2, colorbar_title='Relative Vorticity (Hz) * 1e5')


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In this plot the tracks between 1979-12-01 and 1979-12-30 are selected and
labelled according intensity with a colorbar.

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Example 42a - intensity legend with lines
-----------------------------------------

.. image::  images/fig42a.png
   :scale: 52%



::


   import cf
   import cfplot as cfp
   f=cf.read('cfplot_data/ff_trs_pos.nc')[0]
   cfp.mapset(lonmin=-50, lonmax=50, latmin=20, latmax=80)
   g=f.subspace(time=cf.wi(cf.dt('1979-12-01'), cf.dt('1979-12-10')))
   g=g*1e5
   cfp.levs(0, 12, 1, extend='max')
   cfp.cscale('scale1', below=0, above=13)
   cfp.traj(g, legend_lines=True,  linewidth=2, colorbar_title='Relative Vorticity (Hz) * 1e5')


Selecting legend_lines=True plots lines only and colours them according to the sum of the start and end point divided by two. This can be a useful option when there are lots of trajectories.