A line chart uses points connected by line segments to show information that changes over time.

1. Plot a line chart

1.1 plt.plot

This module contains all the 2D line class which can draw with a variety of line styles, markers and colors.

plt.plot(*args, **kwargs)

import matplotlib.pyplot as plt

plt.plot(*args, **kwargs)

# The kwargs are Line2D properties
(xdata, ydata, linewidth=None, linestyle=None, color=None, marker=None, markersize=None, markeredgewidth=None, markeredgecolor=None, markerfacecolor=None, markerfacecoloralt='none', fillstyle=None, antialiased=None, dash_capstyle=None, solid_capstyle=None, dash_joinstyle=None, solid_joinstyle=None, pickradius=5, drawstyle=None, markevery=None, **kwargs)

Valid kwargs are listed on Line2D properties. All of the line properties can be controlled by keyword arguments,

• xdata
• ydate
• linewidth or lw, float value in points

• linestyle or ls

  • '-' or 'solid' solid line
  • '--' or 'dashed' dashed line
  • '-.' or 'dash_dot' dash-dotted line
  • ':' or 'dotted' dotted line
  • 'None' or ' ' or '' draw nothing

• color or c any matplotlib color, refer to plt.colors()

  • b: blue
  • g: green
  • r: red
  • c: cyan
  • m: magenta
  • y: yellow
  • k: black
  • w: white

• marker The module matplotlib.markers is used by plot and scatter to handle markers.

• label Set the label to s (string or anything printable with ‘%s’ conversion) for auto legend.

1.2 Save to file

savefig(*args, **kwargs) is used to save the current figure.

plt.savefig(fname, dpi=None, facecolor='w', edgecolor='w',
        orientation='portrait', papertype=None, format=None,
        transparent=False, bbox_inches=None, pad_inches=0.1,
        frameon=None)

1.3 Others

plt.subplot(*args, **kwargs)

Return a subplot axes positioned by the given grid definition.

Typical call signature:

plt.subplot(nrows, ncols, plot_number)

# for instance
fig, ax = plt.subplots()

plt.gca(**kwargs)

Get the current Axes instance on the current figure matching the given keyword args, or create one.

plt.clf() Clear the current figure.

2. Decoration

(1) Legend

plt.legend(args, *kwargs),

Other parameters, such as loc, the location of the legend,

'best'         : 0, (only implemented for axes legends)
'upper right'  : 1,
'upper left'   : 2,
'lower left'   : 3,
'lower right'  : 4,
'right'        : 5,
'center left'  : 6,
'center right' : 7,
'lower center' : 8,
'upper center' : 9,
'center'       : 10,

(2) ticks

plt.xticks(*args, **kwargs) and plt.yticks(*args, **kwargs)

Get or set the x-limits of the current tick locations and labels.

# set the locations and labels of the xticks/yticks
locs, labels = plt.xticks(arange(5), ('Tom', 'Dick', 'Harry', 'Sally', 'Sue'))
locs, labels = plt.yticks(arange(5), ('Tom', 'Dick', 'Harry', 'Sally', 'Sue'))

(3) labels

plt.xlabel(s, *args, **kwargs) and plt.ylabel(s, *args, **kwargs) is to set the x/y axis label of the current axis. kwargs is Text properties, listed here.

# plt.xlabel(s, *args, **kwargs)
override = {
        'fontsize'            : 'small',
        'verticalalignment'   : 'top',
        'horizontalalignment' : 'center'
    }

# plt.ylabel(s, *args, **kwargs)
override = {
        'fontsize'            : 'small',
        'verticalalignment'   : 'center',
        'horizontalalignment' : 'right',
        'rotation'            : 'vertical' 
    }

(4) limits of axes

plt.xlim(*args, **kwargs) and plt.ylim(*args, **kwargs) get or set the x/y limits of the current axes.

xmin, xmax = plt.xlim()   # return the current xlim, a length 2 tuple

xmin, xmax = plt.xlim(xmin, xmax)   # OR plt.xlim((xmin, xmax)), set the xlim to xmin, xmax
xmin, xmax = plt.xlim(xmax=3)       # adjust the max leaving min unchanged

Decormation

http://darksair.org/wiki/matplotlib.html