matplotlib.pyplot.boxplot — Matplotlib 3.9.1 documentation (2024)

Draw a box and whisker plot.

The box extends from the first quartile (Q1) to the thirdquartile (Q3) of the data, with a line at the median.The whiskers extend from the box to the farthest data pointlying within 1.5x the inter-quartile range (IQR) from the box.Flier points are those past the end of the whiskers.See https://en.wikipedia.org/wiki/Box_plot for reference.

 Q1-1.5IQR Q1 median Q3 Q3+1.5IQR |-----:-----| o |--------| : |--------| o o |-----:-----|flier <-----------> fliers IQR

Parameters:

xArray or a sequence of vectors.

The input data. If a 2D array, a boxplot is drawn for each columnin x. If a sequence of 1D arrays, a boxplot is drawn for eacharray in x.

notchbool, default: rcParams["boxplot.notch"] (default: False)

Whether to draw a notched boxplot (True), or a rectangularboxplot (False). The notches represent the confidence interval(CI) around the median. The documentation for bootstrapdescribes how the locations of the notches are computed bydefault, but their locations may also be overridden by setting theconf_intervals parameter.

Note

In cases where the values of the CI are less than thelower quartile or greater than the upper quartile, thenotches will extend beyond the box, giving it adistinctive "flipped" appearance. This is expectedbehavior and consistent with other statisticalvisualization packages.

symstr, optional

The default symbol for flier points. An empty string ('') hidesthe fliers. If None, then the fliers default to 'b+'. Morecontrol is provided by the flierprops parameter.

vertbool, default: rcParams["boxplot.vertical"] (default: True)

If True, draws vertical boxes.If False, draw horizontal boxes.

whisfloat or (float, float), default: 1.5

The position of the whiskers.

If a float, the lower whisker is at the lowest datum aboveQ1 - whis*(Q3-Q1), and the upper whisker at the highest datumbelow Q3 + whis*(Q3-Q1), where Q1 and Q3 are the first andthird quartiles. The default value of whis = 1.5 correspondsto Tukey's original definition of boxplots.

If a pair of floats, they indicate the percentiles at which todraw the whiskers (e.g., (5, 95)). In particular, setting this to(0, 100) results in whiskers covering the whole range of the data.

In the edge case where Q1 == Q3, whis is automatically setto (0, 100) (cover the whole range of the data) if autorange isTrue.

Beyond the whiskers, data are considered outliers and are plottedas individual points.

bootstrapint, optional

Specifies whether to bootstrap the confidence intervalsaround the median for notched boxplots. If bootstrap isNone, no bootstrapping is performed, and notches arecalculated using a Gaussian-based asymptotic approximation(see McGill, R., Tukey, J.W., and Larsen, W.A., 1978, andKendall and Stuart, 1967). Otherwise, bootstrap specifiesthe number of times to bootstrap the median to determine its95% confidence intervals. Values between 1000 and 10000 arerecommended.

usermedians1D array-like, optional

A 1D array-like of length len(x). Each entry that is notNone forces the value of the median for the correspondingdataset. For entries that are None, the medians are computedby Matplotlib as normal.

conf_intervalsarray-like, optional

A 2D array-like of shape (len(x), 2). Each entry that is notNone forces the location of the corresponding notch (which isonly drawn if notch is True). For entries that are None,the notches are computed by the method specified by the otherparameters (e.g., bootstrap).

See Also

Box Plot Explained: Interpretation, Examples, & Comparisonseaborn.boxplot — seaborn 0.13.2 documentationBox Plot en Python - Un guide complet pour les débutantsLe box-plot ou la fameuse boîte à moustache

positionsarray-like, optional

The positions of the boxes. The ticks and limits areautomatically set to match the positions. Defaults torange(1, N+1) where N is the number of boxes to be drawn.

widthsfloat or array-like

The widths of the boxes. The default is 0.5, or 0.15*(distancebetween extreme positions), if that is smaller.

patch_artistbool, default: rcParams["boxplot.patchartist"] (default: False)

If False produces boxes with the Line2D artist. Otherwise,boxes are drawn with Patch artists.

tick_labelslist of str, optional

The tick labels of each boxplot.Ticks are always placed at the box positions. If tick_labels is given,the ticks are labelled accordingly. Otherwise, they keep their numericvalues.

Changed in version 3.9: Renamed from labels, which is deprecated since 3.9and will be removed in 3.11.

manage_ticksbool, default: True

If True, the tick locations and labels will be adjusted to matchthe boxplot positions.

autorangebool, default: False

When True and the data are distributed such that the 25th and75th percentiles are equal, whis is set to (0, 100) suchthat the whisker ends are at the minimum and maximum of the data.

meanlinebool, default: rcParams["boxplot.meanline"] (default: False)

If True (and showmeans is True), will try to render themean as a line spanning the full width of the box according tomeanprops (see below). Not recommended if shownotches is alsoTrue. Otherwise, means will be shown as points.

zorderfloat, default: Line2D.zorder = 2

The zorder of the boxplot.

Returns:

dict

A dictionary mapping each component of the boxplot to a listof the Line2D instances created. That dictionary has thefollowing keys (assuming vertical boxplots):

• boxes: the main body of the boxplot showing thequartiles and the median's confidence intervals ifenabled.

• medians: horizontal lines at the median of each box.

• whiskers: the vertical lines extending to the mostextreme, non-outlier data points.

• caps: the horizontal lines at the ends of thewhiskers.

• fliers: points representing data that extend beyondthe whiskers (fliers).

• means: points or lines representing the means.

Other Parameters:

showcapsbool, default: rcParams["boxplot.showcaps"] (default: True)

Show the caps on the ends of whiskers.

showboxbool, default: rcParams["boxplot.showbox"] (default: True)

Show the central box.

See Also

Le diagramme en boîte expliqué : Interprétation, exemples et comparaison

showfliersbool, default: rcParams["boxplot.showfliers"] (default: True)

Show the outliers beyond the caps.

showmeansbool, default: rcParams["boxplot.showmeans"] (default: False)

Show the arithmetic means.

cappropsdict, default: None

The style of the caps.

capwidthsfloat or array, default: None

The widths of the caps.

boxpropsdict, default: None

The style of the box.

whiskerpropsdict, default: None

The style of the whiskers.

flierpropsdict, default: None

The style of the fliers.

medianpropsdict, default: None

The style of the median.

meanpropsdict, default: None

The style of the mean.

labelstr or list of str, optional

Legend labels. Use a single string when all boxes have the same style andyou only want a single legend entry for them. Use a list of strings tolabel all boxes individually. To be distinguishable, the boxes should bestyled individually, which is currently only possible by modifying thereturned artists, see e.g. Boxplots.

In the case of a single string, the legend entry will technically beassociated with the first box only. By default, the legend will show themedian line (result["medians"]); if patch_artist is True, the legendwill show the box Patch artists (result["boxes"]) instead.

New in version 3.9.

dataindexable object, optional

If given, all parameters also accept a string s, which isinterpreted as data[s] (unless this raises an exception).

Notes