Time-height displays.

pyart/core/radar.py

@@ -1026,6 +1026,7 @@ def join_radar(radar1, radar2):
     r2num = date2num(r2dt, estring)
     new_radar.time['data'] = np.append(r1num, r2num)
     new_radar.time['units'] = estring
+    ### TODO Use new updated datetime_utils if accepted
 
     for var in new_radar.fields.keys():
         sh1 = radar1.fields[var]['data'].shape

pyart/graph/radardisplay.py

@@ -17,11 +17,15 @@
 import matplotlib.pyplot as plt
 import numpy as np
 import netCDF4
+from matplotlib.dates import (
+    DateFormatter, SecondLocator, MinuteLocator,
+    HourLocator, DayLocator)
 
 from . import common
 from ..core.transforms import antenna_to_cartesian
 from ..core.transforms import antenna_vectors_to_cartesian
 from ..core.transforms import corner_to_point
+from ..util.datetime_utils import datetimes_from_radar
 
 
 class RadarDisplay(object):
@@ -486,7 +490,10 @@ def plot_vpt(self, field, mask_tuple=None, vmin=None, vmax=None,
                  axislabels=(None, None), axislabels_flag=True,
                  colorbar_flag=True, colorbar_label=None,
                  colorbar_orient='vertical', edges=True,
-                 filter_transitions=True, ax=None, fig=None):
+                 filter_transitions=True,
+                 time_axis_flag=False,
+                 date_time_form=None, tz=None,
+                 ax=None, fig=None):
         """
         Plot a VPT scan.
 
@@ -542,6 +549,15 @@ def plot_vpt(self, field, mask_tuple=None, vmin=None, vmax=None,
             sweeps from the plot.  False will include these rays in the plot.
             No rays are filtered when the antenna_transition attribute of the
             underlying radar is not present.
+        time_axis_flag : bool
+            True to plot the x-axis as time. False uses the index number.
+            Default is False - index-based.
+        date_time_form : str, optional
+            Format of the time string for x-axis labels. Parameter is
+            ignored if time_axis_flag is set to False.
+        tz : str, optional
+            Time zone info to use when creating axis labels (see datetime).
+            Parameter is ignored if time_axis_flag is set to False.
         ax : Axis
             Axis to plot on. None will use the current axis.
         fig : Figure
@@ -567,6 +583,11 @@ def plot_vpt(self, field, mask_tuple=None, vmin=None, vmax=None,
             x = np.arange(data.shape[1])
             y = self.ranges / 1000.
 
+        # set up the time axis
+        if time_axis_flag:
+            self._set_vpt_time_axis(ax, date_time_form=date_time_form, tz=tz)
+            x = datetimes_from_radar(radar)
+
         # mask the data where outside the limits
         if mask_outside:
             data = np.ma.masked_invalid(data)
@@ -579,7 +600,7 @@ def plot_vpt(self, field, mask_tuple=None, vmin=None, vmax=None,
             self._set_vpt_title(field, title, ax)
 
         if axislabels_flag:
-            self._label_axes_vpt(axislabels, ax)
+            self._label_axes_vpt(axislabels, time_axis_flag, ax)
 
         # add plot and field to lists
         self.plots.append(pm)
@@ -933,6 +954,11 @@ def label_xaxis_rays(self, ax=None):
         ax = common.parse_ax(ax)
         ax.set_xlabel('Ray number (unitless)')
 
+    def label_xaxis_time(self, ax=None):
+        """ Label the yaxis with the default label for rays. """
+        ax = common.parse_ax(ax)
+        ax.set_xlabel('Time (HH:MM)')
+
     def label_yaxis_field(self, field, ax=None):
         """ Label the yaxis with the default label for a field units. """
         ax = common.parse_ax(ax)
@@ -1007,18 +1033,42 @@ def _label_axes_ray(self, axis_labels, field, ax):
         else:
             ax.set_ylabel(y_label)
 
-    def _label_axes_vpt(self, axis_labels, ax):
+    def _label_axes_vpt(self, axis_labels, time_axis_flag, ax):
         """ Set the x and y axis labels for a PPI plot. """
         x_label, y_label = axis_labels
         if x_label is None:
-            self.label_xaxis_rays(ax)
+            if time_axis_flag:
+                self.label_xaxis_time(ax)
+            else:
+                self.label_xaxis_rays(ax)
         else:
             ax.set_xlabel(x_label)
         if y_label is None:
             self.label_yaxis_z(ax)
         else:
             ax.set_ylabel(y_label)
 
+    def _set_vpt_time_axis(self, ax, date_time_form=None, tz=None):
+        """ Set the x axis as a time formatted axis.
+
+        Parameters
+        ----------
+        ax : Matplotlib axis instance
+            Axis to plot. None will use the current axis.
+        date_time_form : str
+            Format of the time string for x-axis labels.
+        tz : str
+            Time zone info to use when creating axis labels (see datetime).
+        """
+        if date_time_form is None:
+            date_time_form = '%H:%M'
+
+        # Set the date format
+        date_Fmt = DateFormatter(date_time_form, tz=tz)
+
+        # Turn the tick marks outward
+        ax.tick_params(which='both', direction='out')
+
     ##########################
     # name generator methods #
     ##########################

pyart/graph/tests/test_radar_display.py

@@ -137,7 +137,7 @@ def test_radardisplay_user_specified_labels():
     assert ax.get_xlabel() == 'baz'
     assert ax.get_ylabel() == 'qux'
 
-    display._label_axes_vpt(('nick', 'nock'), ax)
+    display._label_axes_vpt(('nick', 'nock'), False, ax)
     assert ax.get_xlabel() == 'nick'
     assert ax.get_ylabel() == 'nock'
     plt.close()

pyart/util/datetime_utils.py

@@ -1,30 +1,59 @@
 """ Functions for converting date and time between various forms """
 
-from netCDF4 import num2date
+from netCDF4 import num2date, date2num
 
+EPOCH_UNITS = "seconds since 1970-01-01T00:00:00Z"
 
-def datetime_from_radar(radar):
+
+def datetime_from_radar(radar, epoch=False):
     """ Return a datetime for the first ray in a Radar. """
-    return num2date(radar.time['data'][0], radar.time['units'])
+    if epoch:
+        dtrad = num2date(radar.time['data'][0], radar.time['units'])
+        epnum = date2num(dtrad, EPOCH_UNITS)
+        return num2date(epnum, EPOCH_UNITS)
+    else:
+        return num2date(radar.time['data'][0], radar.time['units'])
 
 
-def datetimes_from_radar(radar):
+def datetimes_from_radar(radar, epoch=False):
     """ Return an array of datetimes for the rays in a Radar. """
-    return num2date(radar.time['data'][:], radar.time['units'])
+    if epoch:
+        dtrad = num2date(radar.time['data'][:], radar.time['units'])
+        epnum = date2num(dtrad, EPOCH_UNITS)
+        return num2date(epnum, EPOCH_UNITS)
+    else:
+        return num2date(radar.time['data'][:], radar.time['units'])
 
 
-def datetime_from_dataset(dataset):
+def datetime_from_dataset(dataset, epoch=False):
     """ Return a datetime for the first time in a netCDF Dataset. """
-    return num2date(dataset.variables['time'][0],
-                    dataset.variables['time'].units)
+    if epoch:
+        dtdata = num2date(dataset.variables['time'][0],
+                          dataset.variables['time'].units)
+        epnum = date2num(dtdata, EPOCH_UNITS)
+        return num2date(epnum, EPOCH_UNITS)
+    else:
+        return num2date(dataset.variables['time'][0],
+                        dataset.variables['time'].units)
 
 
-def datetimes_from_dataset(dataset):
+def datetimes_from_dataset(dataset, epoch=False):
     """ Return an array of datetimes for the times in a netCDF Dataset. """
-    return num2date(dataset.variables['time'][:],
-                    dataset.variables['time'].units)
+    if epoch:
+        dtdata = num2date(dataset.variables['time'][:],
+                          dataset.variables['time'].units)
+        epnum = date2num(dtdata, EPOCH_UNITS)
+        return num2date(epnum, EPOCH_UNITS)
+    else:
+        return num2date(dataset.variables['time'][:],
+                        dataset.variables['time'].units)
 
 
-def datetime_from_grid(grid):
+def datetime_from_grid(grid, epoch=False):
     """ Return a datetime for the volume start in a Grid. """
-    return num2date(grid.time['data'][0], grid.time['units'])
+    if epoch:
+        dtrad = num2date(grid.time['data'][0], grid.time['units'])
+        epnum = date2num(dtrad, EPOCH_UNITS)
+        return num2date(epnum, EPOCH_UNITS)
+    else:
+        return num2date(grid.time['data'][0], grid.time['units'])