Better time axis formatting for plots

requake/plot/plot_slip.py

@@ -12,10 +12,10 @@
 import logging
 import matplotlib as mpl
 import matplotlib.pyplot as plt
-import matplotlib.dates as mdates
 from matplotlib import cm
 from matplotlib import colors
 import numpy as np
+from .plot_utils import format_time_axis
 from ..families.families import FamilyNotFoundError, read_selected_families
 from ..formulas.slip import mag_to_slip_in_cm
 from ..config.rq_setup import rq_exit
@@ -37,13 +37,6 @@ def plot_slip(config):
         logger.error(m)
         rq_exit(1)
     fig, ax = plt.subplots(figsize=(8, 4))
-    years = mdates.YearLocator()   # every year
-    months = mdates.MonthLocator()  # every month
-    yearsFmt = mdates.DateFormatter('%Y')
-    ax.xaxis.set_major_locator(years)
-    ax.xaxis.set_major_formatter(yearsFmt)
-    ax.xaxis.set_minor_locator(months)
-    ax.xaxis.grid(True)
     ax.tick_params(which='both', top=True, labeltop=True)
     ax.tick_params(axis='x', which='both', direction='in')
 
@@ -64,6 +57,8 @@ def plot_slip(config):
             lw=1, marker='o', color=cmap(norm(fn % 10)),
             label=label)
         lines.append(line)
+    # time axis formatting must be done here, before setting limits below
+    format_time_axis(ax, which='xaxis')
     # get limits, that we will re-apply later
     xlim = ax.get_xlim()
     ylim = ax.get_ylim()

requake/plot/plot_timespans.py

@@ -12,10 +12,10 @@
 import logging
 import matplotlib as mpl
 import matplotlib.pyplot as plt
-import matplotlib.dates as mdates
 from matplotlib import cm
 from matplotlib import colors
 import numpy as np
+from .plot_utils import format_time_axis
 from ..families.families import FamilyNotFoundError, read_selected_families
 from ..config.rq_setup import rq_exit
 logger = logging.getLogger(__name__.rsplit('.', maxsplit=1)[-1])
@@ -36,13 +36,6 @@ def plot_timespans(config):
         logger.error(m)
         rq_exit(1)
     fig, ax = plt.subplots(figsize=(8, 8))
-    years = mdates.YearLocator()   # every year
-    months = mdates.MonthLocator()  # every month
-    yearsFmt = mdates.DateFormatter('%Y')
-    ax.xaxis.set_major_locator(years)
-    ax.xaxis.set_major_formatter(yearsFmt)
-    ax.xaxis.set_minor_locator(months)
-    ax.xaxis.grid(True)
     ax.tick_params(which='both', top=True, labeltop=True)
     ax.tick_params(axis='x', which='both', direction='in')
 
@@ -69,13 +62,6 @@ def plot_timespans(config):
             'but "distance_from_lon" and/or "distance_from_lat" '
             'are not specified')
         rq_exit(1)
-    if sort_by == 'time':
-        years = mdates.YearLocator()   # every year
-        months = mdates.MonthLocator()  # every month
-        yearsFmt = mdates.DateFormatter('%Y')
-        ax.yaxis.set_major_locator(years)
-        ax.yaxis.set_major_formatter(yearsFmt)
-        ax.yaxis.set_minor_locator(months)
     for family in families:
         fn = family.number
         label = (
@@ -105,6 +91,9 @@ def plot_timespans(config):
             times, yvals, lw=1, marker='o', color=cmap(norm(fn % 10)),
             label=label)
         lines.append(line)
+    format_time_axis(ax, which='xaxis')
+    if sort_by == 'time':
+        format_time_axis(ax, which='yaxis')
     ax.set_xlabel('Time')
     ax.set_ylabel(ylabel)
     sm = cm.ScalarMappable(cmap=cmap, norm=norm)

requake/plot/plot_utils.py

@@ -0,0 +1,42 @@
+# -*- coding: utf8 -*-
+# SPDX-License-Identifier: GPL-3.0-or-later
+"""
+Plot utils.
+
+:copyright:
+    2021-2024 Claudio Satriano <[email protected]>
+:license:
+    GNU General Public License v3.0 or later
+    (https://www.gnu.org/licenses/gpl-3.0-standalone.html)
+"""
+import matplotlib.dates as mdates
+
+
+def format_time_axis(ax, which='both'):
+    """
+    Format the time axis of a Matplotlib plot.
+    """
+    if which == 'both':
+        axes = [ax.xaxis, ax.yaxis]
+    elif which == 'xaxis':
+        axes = [ax.xaxis]
+    elif which == 'yaxis':
+        axes = [ax.yaxis]
+    else:
+        raise ValueError(f'Invalid value for "which": {which}')
+    for axis in axes:
+        dmin, dmax = axis.get_data_interval()
+        timespan = dmax-dmin
+        if timespan > 365:
+            _major_locator = mdates.YearLocator()   # every year
+            _major_fmt = mdates.DateFormatter('%Y')
+            _minor_locator = mdates.MonthLocator()  # every month
+        else:
+            _major_locator = mdates.AutoDateLocator(minticks=3, maxticks=7)
+            _major_fmt = mdates.ConciseDateFormatter(_major_locator)
+            _minor_locator = mdates.DayLocator()  # every day
+        axis.set_major_locator(_major_locator)
+        axis.set_major_formatter(_major_fmt)
+        axis.set_minor_locator(_minor_locator)
+        axis.grid(True, which='major', linestyle='--', color='0.5')
+        axis.grid(True, which='minor', linestyle=':', color='0.8')