%matplotlib inline

from __future__ import print_function, division
import numpy as np
import matplotlib.pyplot as plt

fig, ax = plt.subplots()

ax.text(0.5, 0.5, 'hello world: $\int_0^\infty e^x dx$', size=24, ha='center', va='center');

fig.text(0, 0, 'bottom-left corner')
fig.text(1, 1, 'top-right corner', ha='left', va='top')
fig

fig, ax = plt.subplots()

ax.annotate('0.25 on axes', (0.25, 0.25), textcoords='axes fraction', size=20)
ax.annotate('0.25 on data', (0.25, 0.25), textcoords='data', size=20)
ax.set_ylim(0, 0.5);

fig, ax = plt.subplots()

ax.annotate('origin is here', (0, 0), (0.75, 0.75),
            arrowprops=dict(arrowstyle='->', connectionstyle='arc3, rad=0.5'),
            xycoords='data', textcoords='axes fraction');

fig, ax = plt.subplots()

x = np.linspace(0, 10)
ax.plot(x, np.sin(x))

ax.xaxis.set_major_locator(plt.MultipleLocator(0.8))
ax.yaxis.set_major_locator(plt.MaxNLocator(3))

ax.xaxis.set_minor_locator(plt.MultipleLocator(0.4))
ax.yaxis.set_minor_locator(plt.NullLocator())  # no ticks (default)

ax.xaxis.set_major_formatter(plt.FormatStrFormatter('%.2f'))  # float with two decimals


def tickformat(val, pos):
    if val > 0:
        return "positive"
    elif val < 0:
        return "negative"
    else:
        return "zero"
    
ax.yaxis.set_major_formatter(plt.FuncFormatter(tickformat))
ax.set_ylim(-1.2, 1.2);