Plots

pymc3.plots.traceplot(trace, varnames=None, transform=<function identity_transform>, figsize=None, lines=None, combined=False, plot_transformed=False, grid=False, alpha=0.35, priors=None, prior_alpha=1, prior_style='--', ax=None, live_plot=False, skip_first=0, refresh_every=100, roll_over=1000)

Plot samples histograms and values.

Parameters:
  • trace (result of MCMC run) –
  • varnames (list of variable names) – Variables to be plotted, if None all variable are plotted
  • transform (callable) – Function to transform data (defaults to identity)
  • figsize (figure size tuple) – If None, size is (12, num of variables * 2) inch
  • lines (dict) – Dictionary of variable name / value to be overplotted as vertical lines to the posteriors and horizontal lines on sample values e.g. mean of posteriors, true values of a simulation. If an array of values, line colors are matched to posterior colors. Otherwise, a default red line
  • combined (bool) – Flag for combining multiple chains into a single chain. If False (default), chains will be plotted separately.
  • plot_transformed (bool) – Flag for plotting automatically transformed variables in addition to original variables (defaults to False).
  • grid (bool) – Flag for adding gridlines to histogram. Defaults to True.
  • alpha (float) – Alpha value for plot line. Defaults to 0.35.
  • priors (iterable of PyMC distributions) – PyMC prior distribution(s) to be plotted alongside posterior. Defaults to None (no prior plots).
  • prior_alpha (float) – Alpha value for prior plot. Defaults to 1.
  • prior_style (str) – Line style for prior plot. Defaults to ‘–’ (dashed line).
  • ax (axes) – Matplotlib axes. Accepts an array of axes, e.g.:
  • live_plot (bool) – Flag for updating the current figure while sampling
  • skip_first (int) – Number of first samples not shown in plots (burn-in). This affects frequency and stream plots.
  • refresh_every (int) – Period of plot updates (in sample number)
  • roll_over (int) –

    Width of the sliding window for the sample stream plots: last roll_over samples are shown (no effect on frequency plots).

    >>> fig, axs = plt.subplots(3, 2) # 3 RVs
>>> pymc3.traceplot(trace, ax=axs)

    Creates own axes by default.
Returns:

ax (matplotlib axes)
pymc3.plots.plot_posterior(trace, varnames=None, transform=<function identity_transform>, figsize=None, text_size=16, alpha_level=0.05, round_to=3, point_estimate='mean', rope=None, ref_val=None, kde_plot=False, plot_transformed=False, ax=None, **kwargs)

Plot Posterior densities in style of John K. Kruschke book.

Parameters:
  • trace (result of MCMC run) –
  • varnames (list of variable names) – Variables to be plotted, if None all variable are plotted
  • transform (callable) – Function to transform data (defaults to identity)
  • figsize (figure size tuple) – If None, size is (12, num of variables * 2) inch
  • text_size (int) – Text size of the point_estimates, axis ticks, and HPD (Default:16)
  • alpha_level (float) – Defines range for High Posterior Density
  • round_to (int) – Controls formatting for floating point numbers
  • point_estimate (str) – Must be in (‘mode’, ‘mean’, ‘median’)
  • rope (list or numpy array) – Lower and upper values of the Region Of Practical Equivalence
  • ref_val (bool) – display the percentage below and above ref_val
  • kde_plot (bool) – if True plot a KDE instead of a histogram. For discrete variables this argument is ignored.
  • plot_transformed (bool) – Flag for plotting automatically transformed variables in addition to original variables (defaults to False).
  • ax (axes) – Matplotlib axes. Defaults to None.
  • **kwargs – Passed as-is to plt.hist() or plt.plot() function, depending on the value of the argument kde_plot Some defaults are added, if not specified color=’#87ceeb’ will match the style in the book
Returns:

ax (matplotlib axes)
pymc3.plots.forestplot(trace_obj, varnames=None, transform=<function identity_transform>, alpha=0.05, quartiles=True, rhat=True, main=None, xtitle=None, xlim=None, ylabels=None, chain_spacing=0.05, vline=0, gs=None, plot_transformed=False, **plot_kwargs)

Forest plot (model summary plot).

Generates a “forest plot” of 100*(1-alpha)% credible intervals for either the set of variables in a given model, or a specified set of nodes.

Parameters:
  • trace_obj (NpTrace or MultiTrace object) – Trace(s) from an MCMC sample.
  • varnames (list) – List of variables to plot (defaults to None, which results in all variables plotted).
  • transform (callable) – Function to transform data (defaults to identity)
  • (optional) (vline) – Alpha value for (1-alpha)*100% credible intervals (defaults to 0.05).
  • (optional) – Flag for plotting the interquartile range, in addition to the (1-alpha)*100% intervals (defaults to True).
  • (optional) – Flag for plotting Gelman-Rubin statistics. Requires 2 or more chains (defaults to True).
  • (optional) – Title for main plot. Passing False results in titles being suppressed; passing None (default) results in default titles.
  • (optional) – Label for x-axis. Defaults to no label
  • (optional) – Range for x-axis. Defaults to matplotlib’s best guess.
  • (optional) – User-defined labels for each variable. If not provided, the node __name__ attributes are used.
  • (optional) – Plot spacing between chains (defaults to 0.05).
  • (optional) – Location of vertical reference line (defaults to 0).
  • gs (GridSpec) – Matplotlib GridSpec object. Defaults to None.
  • plot_transformed (bool) – Flag for plotting automatically transformed variables in addition to original variables (defaults to False).
  • plot_kwargs (dict) – Optional arguments for plot elements. Currently accepts ‘fontsize’, ‘linewidth’, ‘color’, ‘marker’, and ‘markersize’.
Returns:

gs (matplotlib GridSpec)
pymc3.plots.autocorrplot(trace, varnames=None, max_lag=100, burn=0, plot_transformed=False, symmetric_plot=False, ax=None, figsize=None)

Bar plot of the autocorrelation function for a trace.

Parameters:
  • trace (result of MCMC run) –
  • varnames (list of variable names) – Variables to be plotted, if None all variable are plotted. Vector-value stochastics are handled automatically.
  • max_lag (int) – Maximum lag to calculate autocorrelation. Defaults to 100.
  • burn (int) – Number of samples to discard from the beginning of the trace. Defaults to 0.
  • plot_transformed (bool) – Flag for plotting automatically transformed variables in addition to original variables (defaults to False).
  • symmetric_plot (boolean) – Plot from either [0, +lag] or [-lag, lag]. Defaults to False, [-, +lag].
  • ax (axes) – Matplotlib axes. Defaults to None.
  • figsize (figure size tuple) – If None, size is (12, num of variables * 2) inches. Note this is not used if ax is supplied.
Returns:

ax (matplotlib axes)