plot_ppi(data, r=None, az=None, autoext=True, site=(0, 0, 0), proj=None, elev=0.0, fig=None, ax=111, func='pcolormesh', cg=False, rf=1.0, refrac=False, **kwargs)¶
Plots a Plan Position Indicator (PPI).
The implementation of this plot routine is in cartesian axes and does all coordinate transforms beforehand. This allows zooming into the data as well as making it easier to plot additional data (like gauge locations) without having to convert them to the radar’s polar coordinate system.
cg=Truethe plotting is done in a curvelinear grid axes. Additional data can be plotted in polar coordinates or cartesian coordinates depending which axes object is used.
There is one major caveat concerning the values of
az. Due to the way
rshould give the location of the start of each range bin, while
azshould give the angle also at the begin (i.e. ‘leftmost’) of the beam. This might be in contrast to other conventions, which might define ranges and angles at the center of bin and beam. This affects especially the default values set for
az, but ìt should be possible to accommodate all other conventions by setting
- data (
numpy.ndarray) – The data to be plotted. It is assumed that the first dimension is over the azimuth angles, while the second dimension is over the range bins
- r (
numpy.ndarray) – The ranges. Units may be chosen arbitrarily, unless proj is set. In that case the units must be meters. If None, a default is calculated from the dimensions of
- rf (float) – If present, factor for scaling range axes, defaults to 1.
- az (
numpy.ndarray) – The azimuth angles in degrees. If None, a default is calculated from the dimensions of
- autoext (bool) – This routine uses
matplotlib.pyplot.pcolormeshto draw the bins. As this function needs one set of coordinates more than would usually be provided by
autoextto True automatically extends
azso that all of
datawill be plotted.
- refrac (bool) – If True, the effect of refractivity of the earth’s atmosphere on the
beam propagation will be taken into account. If False, simple
trigonometry will be used to calculate beam propagation.
Functionality for this will be provided by function
wradlib.georef.misc.bin_distance. Therefore, if
rmust be given in meters.
- site (tuple) – Tuple of coordinates of the radar site.
projis not used, this simply becomes the offset for the origin of the coordinate system. If
projis used, values must be given as (longitude, latitude) tuple of geographical coordinates.
- proj (osr spatial reference object) – GDAL OSR Spatial Reference Object describing projection
If this parameter is not None,
sitemust be set. Then the function will attempt to georeference the radar bins and display the PPI in the coordinate system defined by the projection string.
- elev (float or array of same shape as
az) – Elevation angle of the scan or individual azimuths. May improve georeferencing coordinates for larger elevation angles.
- fig (
matplotlib.figure.Figure) – If given, the RHI will be plotted into this figure object. Axes are created as needed. If None, a new figure object will be created or current figure will be used, depending on
- ax (
matplotlib.axes.Axes| matplotlib grid definition) – If matplotlib Axes object is given, the PPI will be plotted into this axes object. If matplotlib grid definition is given (nrows/ncols/plotnumber), axis are created in the specified place. Defaults to ‘111’, only one subplot/axis.
- func (str) – Name of plotting function to be used under the hood. Defaults to ‘pcolormesh’. ‘contour’ and ‘contourf’ can be selected too.
- cg (bool) – If True, the data will be plotted on curvelinear axes.
cgis True, the
cgax- curvelinear Axes (r-theta-grid) is returned.
caax- Cartesian Axes (x-y-grid) and
paax- parasite axes object for plotting polar data can be derived like this:
caax = cgax.parasites paax = cgax.parasites
- data (