Matplotlib.axes.Axes.errorbar() in Python

Matplotlib is a library in Python and it is numerical – mathematical extension for NumPy library. The Axes Class contains most of the figure elements: Axis, Tick, Line2D, Text, Polygon, etc., and sets the coordinate system. And the instances of Axes supports callbacks through a callbacks attribute. Example:

Python3

# Implementation of matplotlib function

import matplotlib.pyplot as plt
import numpy as np

# make an agg figure
fig, ax = plt.subplots()

ax.plot([1, 2, 3])
ax.set_title('matplotlib.axes.Axes.plot() example 1')
fig.canvas.draw()

plt.show()

Output:

matplotlib.axes.Axes.errorbar() Function

The Axes.errorbar() function in axes module of matplotlib library is used to plot y versus x as lines and/or markers with attached errorbars.

Syntax: Axes.errorbar(self, x, y, yerr=None, xerr=None, fmt=”, ecolor=None, elinewidth=None, capsize=None, barsabove=False, lolims=False, uplims=False, xlolims=False, xuplims=False, errorevery=1, capthick=None, *, data=None, **kwargs)

Parameters: This method accept the following parameters that are described below:

• x, y: These parameter are the horizontal and vertical coordinates of the data points.
• fmt: This parameter is an optional parameter and it contains the string value.
• xerr, yerr: These parameter contains an array.And the error array should have positive values.
• ecolor: This parameter is an optional parameter. And it is the color of the errorbar lines with default value NONE.
• elinewidth: This parameter is also an optional parameter. And it is the linewidth of the errorbar lines with default value NONE.
• capsize: This parameter is also an optional parameter. And it is the length of the error bar caps in points with default value NONE.
• barsabove: This parameter is also an optional parameter. It contains boolean value True for plotting errorbars above the plot symbols.Its default value is False.
• lolims, uplims, xlolims, xuplims: These parameter are also an optional parameter. They contain boolean values which is used to indicate that a value gives only upper/lower limits.
• errorevery: This parameter is also an optional parameter. They contain integer values which is used to draws error bars on a subset of the data.

Returns: This returns the container and it is comprises of the following:

• plotline:This returns the Line2D instance of x, y plot markers and/or line.
• caplines:This returns the tuple of Line2D instances of the error bar caps.
• barlinecols:This returns the tuple of LineCollection with the horizontal and vertical error ranges.

Below examples illustrate the matplotlib.axes.Axes.errorbar() function in matplotlib.axes: Example #1:

Python3

# Implementation of matplotlib function

import numpy as np
import matplotlib.pyplot as plt

# example data
xval = np.arange(0.1, 4, 0.5)
yval = np.exp(-xval)

fig, ax = plt.subplots()
ax.errorbar(xval, yval, xerr = 0.4, yerr = 0.5)
plt.show()

Output: Example #2:

Python3

# Implementation of matplotlib function

import numpy as np
import matplotlib.pyplot as plt


fig = plt.figure()
x = np.arange(10)
y = 3 * np.sin(x / 20 * np.pi)
yerr = np.linspace(0.05, 0.2, 10)

plt.errorbar(x, y + 7, yerr = yerr,
             label ='Line1')

plt.errorbar(x, y + 5, yerr = yerr,
             uplims = True, label ='Line2')

plt.errorbar(x, y + 3, yerr = yerr,
             uplims = True, lolims = True,
             label ='Line3')

upperlimits = [True, False] * 5
lowerlimits = [False, True] * 5

plt.errorbar(x, y, yerr = yerr,
             uplims = upperlimits,
             lolims = lowerlimits,
             label ='Line4')

plt.legend(loc ='upper left')
plt.show()

Output: