Errorbars¶

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Title: ErrorBars Element
Dependencies: Plotly
Backends: Plotly; Matplotlib; Bokeh

In [1]:

import numpy as np
import holoviews as hv
hv.extension('plotly')

ErrorBars provide a visual indicator for the variability of the plotted data on a graph. They are usually applied on top of other plots such as scatter, curve or bar plots to indicate the variability in each sample.

ErrorBars may be used to represent symmetric error or asymmetric error. An ErrorBars Element must have one key dimensions representing the samples along the x-axis and two or three value dimensions representing the value of the sample and positive and negative error values associated with that sample or x-axis. See the Tabular Datasets user guide for supported data formats, which include arrays, pandas dataframes and dictionaries of arrays.

Symmetric error¶

By default the ErrorBars Element accepts x- and y-coordinates along with a symmetric error value along y-axis:

In [2]:

np.random.seed(7)
errors = [(0.1*i, np.sin(0.1*i), np.random.rand()/2) for i in np.linspace(0, 100, 11)]
hv.Curve(errors) * hv.ErrorBars(errors)

Out[2]:

Assymetric error¶

ErrorBars is a set of x-/y-coordinates with associated error values along y-axis. Error values may be either symmetric or asymmetric, and thus can be supplied as an Nx3 or Nx4 array (or any of the alternative constructors Chart Elements allow).

In [3]:

errors = [(0.1*i, np.sin(0.1*i), np.random.rand()/2, np.random.rand()/4) for i in np.linspace(0, 100, 11)]
hv.Curve(errors) * hv.ErrorBars(errors, vdims=['y', 'yerrneg', 'yerrpos'])

Out[3]:

Errors along x-axis¶

ErrorBars can be a set of a set of x-/y-coordinates with associated error values along x-axis. The parameter horizontal, when set to True, will set supplied errors along x-axis instead of y-axis.

In [4]:

errors = [(0.1*i, np.sin(0.1*i), np.random.rand()/2) for i in np.linspace(0, 100, 11)]
hv.Curve(errors) * hv.ErrorBars(errors, horizontal=True)

Out[4]:

Errors along x and y axes¶

Two ErrorBars with orthogonal errors can be composed together to give x and y errorbars

In [5]:

yerrors = [(0.1*i, np.sin(0.1*i), np.random.rand()/2, np.random.rand()/4) for i in np.linspace(0, 100, 11)]
xerrors = [(0.1*i, np.sin(0.1*i), np.random.rand()/2, np.random.rand()/4) for i in np.linspace(0, 100, 11)]

(hv.Curve(yerrors)
 * hv.ErrorBars(yerrors, vdims=['y', 'yerrneg', 'yerrpos'])
 * hv.ErrorBars(xerrors, vdims=['y', 'xerrneg', 'xerrpos'], horizontal=True)
)

Out[5]:

For full documentation and the available style and plot options, use hv.help(hv.ErrorBars).

Download this notebook from GitHub (right-click to download).