Making a Matplotlib plot look better #1

Before Everest was climbed, the "World summit record" was the highest mountain summit climbed by a particular date. It seems likely that people in South America reached several peaks well in excess of 6000 m before records began, so the following table (adapted from Wikipedia's World altitude record article starts only with the first recorded ascent of Aconcagua in 1897.

Plotting these data using Matplotlib's default settings gives a rather unappealing figure:

Year	Mountain	Height /m
1897	Aconcagua	6962
1907	Trisul	7120
1911	Pauhunri	7128
1928	Kaufman Peak	7134
1930	Nepal Peak	7177
1930	Jongsong Peak	7462
1931	Kamet	7756
1936	Nanda Devi	7816
1950	Annapurna	8091
1953	Everest	8848

import pylab
# year of first ascent, name and height of highest mountains climbed, in order
summits = [
(1897, 'Aconcagua', 6962.),
(1907, 'Trisul', 7120.),
(1911, 'Pauhunri', 7128.),
(1928, 'Kaufman Peak', 7134.),
(1930, 'Nepal Peak', 7177.),
(1930, 'Jongsong Peak', 7462.),
(1931, 'Kamet', 7756.),
(1936, 'Nanda Devi', 7816.),
(1950, 'Annapurna', 8091.),
(1953, 'Everest', 8848.),
]

# Plot height against year
years = [summit[0] for summit in summits]
heights = [summit[2] for summit in summits]
pylab.plot(years, heights)
pylab.show()

A better-looking graph can be produced by customizing the various elements of the plot as in the following listing:

import matplotlib.pyplot as plt

# year of first ascent, name and height of highest mountains climbed, in order
summits = [
(1897, 'Aconcagua', 6962.),
(1907, 'Trisul', 7120.),
(1911, 'Pauhunri', 7128.),
(1928, 'Kaufman Peak', 7134.),
(1930, 'Nepal Peak', 7177.),
(1930, 'Jongsong Peak', 7462.),
(1931, 'Kamet', 7756.),
(1936, 'Nanda Devi', 7816.),
(1950, 'Annapurna', 8091.),
(1953, 'Everest', 8848.),
]

# Colours for the plot
c1, c2 = '#000088', '#ccffcc'

fig, ax = plt.subplots(facecolor='w')

# Plot height against year
years = [summit[0] for summit in summits]
heights = [summit[2] for summit in summits]
ax.plot(years, heights, ls='', marker='^', alpha=0.5, c='k', ms=9)

# The default axis background colour is white anyway, but for reference:
ax.set_axis_bgcolor('#ffffff')

# Turn on major gridlines for the y-axis and style them
ax.yaxis.grid(True, which='major', color=c2, ls='-', lw=1.5)

# Remove all spines except the bottom one (x-axis) and style it
ax.spines['top'].set_visible(False)
ax.spines['right'].set_visible(False)
ax.spines['bottom'].set_linewidth(1.5)
ax.spines['bottom'].set_color(c2)
ax.spines['left'].set_visible(False)

# Remove tick marks from y-axis and style x-axis tick marks
plt.tick_params(axis='y', length=0)
plt.tick_params(axis='x', top='off', length=7, color=c1, direction='out')

# Pad the top a bit so the highest gridline isn't clipped
ax.set_ylim(6500,9050)

# Label the axes
ax.set_xlabel('Year', color=c1, alpha=0.8)
ax.set_ylabel('Height /m', color=c1, alpha=0.8)

# Style the tick labels
for tick_label in ax.yaxis.get_ticklabels():
    tick_label.set_fontsize(12)
    tick_label.set_fontstyle('italic')
    tick_label.set_color(c1)
for tick_label in ax.xaxis.get_ticklabels():
    tick_label.set_fontsize(12)
    tick_label.set_fontstyle('italic')
    tick_label.set_color(c1)

# Annotate the plot with mountain names, offset suitably so they don't overlap
voffsets = [10,-15,10,-15,10,-15,-15,10,10,-15]
for (x, name, y), voffset in zip(summits, voffsets):
    plt.annotate(name, xy=(x,y), xytext=(0,voffset),
        textcoords = 'offset points', ha = 'center', va = 'bottom',
        fontsize=12, alpha=0.8, color=c1,
        )

plt.show()