Dash patterns of lines are designated by the linestyle or ls parameter. It can sometimes be used as a positional argument for convenience. For example, in line plots, we can specify the following:

• 'solid' or '-': Solid line; default
• 'dashed' or '--': Equally spaced dashes
• 'dashdot' or '-.': Alternate dashes and dots
• '.': Loose dotted line
• ':': Packed dotted line
• 'None', ' ', '': No visible line
• (offset, on-off-dash-seq): Customized dashes

The following is an example of lines in different dash patterns:

import matplotlib.pyplot as plt

# Prepare 4 data series of sine curves
y = [np.sin(i) for i in np.arange(0.0, 10.0, 0.1)]

dash_capstyles = ['-','--','-.','.',':']

# Plot each data series in different cap dash styles
for i,x in enumerate(dash_capstyles):
    plt.plot([n*(i+1) for n in y],x,label=x)

plt.legend(fontsize=16,loc='lower left')
plt.show()

We can see the effect of each dash style in the following figure: