gistfile1.py

import matplotlib.pyplot as plt
import numpy as np

calls = np.random.random_integers(100, 5000, 31)
days = np.arange(1, 32)

fig, ax = plt.subplots()

# Default width is already 0.8 but you can adjust it if you so wish
width = 0.8

# Need to align center to make sure the ticks are directly below the bars
bar = ax.bar(days, calls, color='#4f7094', width=width, align='center')
ax.set_xticks(days)

for rect in bar[1::2]:
    rect.set_color('#1e3046')

# Removes the spines around the border.
for spine in ['top', 'left', 'bottom', 'right']: 
    ax.spines[spine].set_visible(False)

# Removes unwanted ticks and labels
tick_args = dict(which='both', left='off', labelleft='off', right='off',
                 top='off', bottom='off', labelbottom='on')
plt.tick_params(**tick_args)

ax.set_xlim(0,32)

plt.tight_layout() # Sorts out the overlapping objects

plt.show()