NCL_bar_14.py

This script illustrates the following concepts:

• Drawing an XY curve on top of filled bars

• Filling the bars in a bar plot with different colors

• Setting the minimum/maximum value of the X and Y axis in a bar plot

• Rotating the Y axis string 270 degrees

• Drawing a Y reference line in an XY plot

• Changing the color and thickness of a Y reference line

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

• Original NCL script: https://www.ncl.ucar.edu/Applications/Scripts/bar_14.ncl

• Original NCL plots: https://www.ncl.ucar.edu/Applications/Images/bar_14_lg.png

Import packages

import numpy as np
import matplotlib.pyplot as plt
import geocat.viz as gv

Generate data:

# Generate 12 numbers from 0 to 100 in a uniform distribution
y1 = np.random.uniform(0, 100, 12)

# Generate 12 numbers with an average of 30 and a standard deviation of 10
y2 = np.random.normal(30, 10, 12)

# Create an array from 1 to 12 with 12 numbers
months = np.linspace(1, 12, 12)

Plot:

# Create figure with figure size (width, height) in inches and create axes
fig = plt.figure(figsize=(6, 5.25))
ax = plt.axes()

# Plot the bar chart, line chart, and a horizontal line with varying colors and linewidths
plt.bar(months, y1, color="yellow", edgecolor="k", linewidth=.5)
plt.plot(months, y2, color="b", linewidth=1)
plt.hlines(40, 0, 13, color="b", linewidth=1)

# Use geocat.viz.util convenience function to add titles and set their size
gv.set_titles_and_labels(ax,
                         maintitle="XY curve over a bar chart",
                         maintitlefontsize=16,
                         ylabel="mm",
                         labelfontsize=14)

# Use geocat.viz.util convenience function to set axes tick values and labels
gv.set_axes_limits_and_ticks(ax,
                             xticks=np.linspace(0, 12, 5),
                             xticklabels=np.linspace(0, 12, 5),
                             xlim=(0, 13),
                             yticks=np.linspace(0, 100, 6),
                             ylim=(0, 100))

# Create the right axis
axRHS = ax.twinx()

# Set the right axis title and size while rotating it 270 degrees and adding a whitespace padding
axRHS.set_ylabel((u"\u00b0" + "C"), size=14, rotation=270, labelpad=25)

# Use geocat.viz.util convenience function to set axes tick values and labels for the right axis
gv.set_axes_limits_and_ticks(axRHS,
                             yticks=np.linspace(0, 100, 6),
                             yticklabels=np.linspace(0, 50, 6, dtype=int))

# Use geocat.viz.util convenience function to add major and minor tick lines
gv.add_major_minor_ticks(ax, x_minor_per_major=3, y_minor_per_major=4)

# Adjust tick and ticklabel sizes for each axis
ax.tick_params(axis="x", size=12, labelsize=12)
ax.tick_params(axis="y", size=12, labelsize=12)
axRHS.tick_params(axis="y", size=12, labelsize=12)

# Display plot
plt.tight_layout()
plt.show()