NCL_axes_3.py

This script illustrates the following concepts:

• Removing the border, tickmarks, and labels from an XY plot

• Drawing vertical grid lines on an XY plot

• Making an axis logarithmic in an XY plot

• Drawing four XY plots in the same figure using matplotlib.subplots

• Drawing Y axis labels using exponents

See following URLs to see the reproduced NCL plot & script:

• Original NCL script: https://www.ncl.ucar.edu/Applications/Scripts/axes_3.ncl

• Original NCL plots: https://www.ncl.ucar.edu/Applications/Images/axes_3_lg.png

Import packages:

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.ticker import NullFormatter

import geocat.viz as gv

Create dummy data for XY plots

npts = 500

x = 500 + 0.9 * np.arange(0, npts) * np.cos(np.pi / 100 * np.arange(0, npts))
y = 500 + 0.9 * np.arange(0, npts) * np.sin(np.pi / 100 * np.arange(0, npts))

Plot:

# Create subplots
fig, axes = plt.subplots(nrows=2,
                         ncols=2,
                         figsize=(10, 10),
                         gridspec_kw=dict(wspace=0.5, hspace=0.5))

# Subplot(0, 0): Create plot with linear axes and full perimeter
axes[0][0].plot(x, y, color='orange')

# Use geocat.viz.util convenience function to set titles and labels
gv.set_titles_and_labels(axes[0][0],
                         maintitle="Perimeter Background",
                         xlabel="Linear",
                         ylabel="Linear")

# Use geocat.viz.util convenience function to add minor and major tick lines
gv.add_major_minor_ticks(axes[0][0],
                         x_minor_per_major=2,
                         y_minor_per_major=2,
                         labelsize=10)

# Use geocat.viz.util convenience function to set axes limits and tick labels
gv.set_axes_limits_and_ticks(axes[0][0],
                             xlim=(0, 900),
                             ylim=(100, 1000),
                             xticks=range(0, 901, 100),
                             yticks=range(100, 1001, 100))

# Subplot(0, 1): Create plot with log y-axis and gridlines
axes[0][1].set_yscale('log')
axes[0][1].plot(x, y, color='limegreen')

# Use geocat.viz.util convenience function to set titles and labels
gv.set_titles_and_labels(axes[0][1],
                         maintitle="Grid Background",
                         xlabel="Linear",
                         ylabel="Logarithmic")

# Use geocat.viz.util convenience function to add minor and major tick lines
gv.add_major_minor_ticks(axes[0][1],
                         x_minor_per_major=2,
                         y_minor_per_major=2,
                         labelsize=10)

# Use geocat.viz.util convenience function to set axes limits and tick labels
gv.set_axes_limits_and_ticks(axes[0][1],
                             xlim=(0, 900),
                             ylim=(100, 1000),
                             xticks=range(0, 901, 100))

# Remove labels for minor ticks on log scale
axes[0][1].yaxis.set_minor_formatter(NullFormatter())

# Turn on vertical gridlines
axes[0][1].grid(True, which='major', axis='x', color='black')

# Subplot(1, 0): Create plot with log x-axis and half-axis background
axes[1][0].set_xscale('log')
axes[1][0].plot(x, y, color='blueviolet')

# Use geocat.viz.util convenience function to set titles and labels
gv.set_titles_and_labels(axes[1][0],
                         maintitle="Half-Axis Background",
                         xlabel="Logarithmic",
                         ylabel="Linear")

# Use geocat.viz.util convenience function to add minor and major tick lines
gv.add_major_minor_ticks(axes[1][0],
                         x_minor_per_major=2,
                         y_minor_per_major=2,
                         labelsize=10)

# Use geocat.viz.util convenience function to set axes limits and tick labels
gv.set_axes_limits_and_ticks(axes[1][0],
                             xlim=(10, 1000),
                             ylim=(100, 1000),
                             yticks=range(100, 1001, 100))

# Remove labels for minor ticks on log scale
axes[1][0].xaxis.set_minor_formatter(NullFormatter())

# Hide the top and right side borders
axes[1][0].spines['right'].set_visible(False)
axes[1][0].spines['top'].set_visible(False)

# Hide the top and right side tick marks
axes[1][0].yaxis.set_ticks_position('left')
axes[1][0].xaxis.set_ticks_position('bottom')

# Subplot(1, 1) Create plot with log axes and no background
axes[1][1].set_xscale('log')
axes[1][1].set_yscale('log')
axes[1][1].plot(x, y, color='firebrick')

# Use geocat.viz.util convenience function to set titles and labels
gv.set_titles_and_labels(axes[1][1],
                         maintitle="No Background",
                         xlabel="Logarithmic",
                         ylabel="Logarithmic")

# Use geocat.viz.util convenience function to set axes limits and tick labels
gv.set_axes_limits_and_ticks(axes[1][1], xlim=(31.628, 1000), ylim=(100, 1000))

# Remove the border
axes[1][1].set_frame_on(False)

# Remove all tick marks and their labels
axes[1][1].tick_params(which='both',
                       top=False,
                       bottom=False,
                       left=False,
                       right=False,
                       labeltop=False,
                       labelbottom=False,
                       labelleft=False,
                       labelright=False)

# Show plot
plt.show()