Help on function hist in module matplotlib.pyplot:
hist(x, bins=None, range=None, normed=False, weights=None, cumulative=False, bottom=None, histtype=u'bar', align=u'mid', orientation=u'vertical', rwidth=None, log=False, color=None, label=None, stacked=False, hold=None, data=None, **kwargs)
Plot a histogram.
Compute and draw the histogram of *x*. The return value is a
tuple (*n*, *bins*, *patches*) or ([*n0*, *n1*, ...], *bins*,
[*patches0*, *patches1*,...]) if the input contains multiple
data.
Multiple data can be provided via *x* as a list of datasets
of potentially different length ([*x0*, *x1*, ...]), or as
a 2-D ndarray in which each column is a dataset. Note that
the ndarray form is transposed relative to the list form.
Masked arrays are not supported at present.
Parameters
----------
x : (n,) array or sequence of (n,) arrays
Input values, this takes either a single array or a sequency of
arrays which are not required to be of the same length
bins : integer or array_like or 'auto', optional
If an integer is given, `bins + 1` bin edges are returned,
consistently with :func:`numpy.histogram` for numpy version >=
1.3.
Unequally spaced bins are supported if `bins` is a sequence.
If Numpy 1.11 is installed, may also be ``'auto'``.
Default is taken from the rcParam ``hist.bins``.
range : tuple or None, optional
The lower and upper range of the bins. Lower and upper outliers
are ignored. If not provided, `range` is (x.min(), x.max()). Range
has no effect if `bins` is a sequence.
If `bins` is a sequence or `range` is specified, autoscaling
is based on the specified bin range instead of the
range of x.
Default is ``None``
normed : boolean, optional
If `True`, the first element of the return tuple will
be the counts normalized to form a probability density, i.e.,
``n/(len(x)`dbin)``, i.e., the integral of the histogram will sum
to 1. If *stacked* is also *True*, the sum of the histograms is
normalized to 1.
Default is ``False``
weights : (n, ) array_like or None, optional
An array of weights, of the same shape as `x`. Each value in `x`
only contributes its associated weight towards the bin count
(instead of 1). If `normed` is True, the weights are normalized,
so that the integral of the density over the range remains 1.
Default is ``None``
cumulative : boolean, optional
If `True`, then a histogram is computed where each bin gives the
counts in that bin plus all bins for smaller values. The last bin
gives the total number of datapoints. If `normed` is also `True`
then the histogram is normalized such that the last bin equals 1.
If `cumulative` evaluates to less than 0 (e.g., -1), the direction
of accumulation is reversed. In this case, if `normed` is also
`True`, then the histogram is normalized such that the first bin
equals 1.
Default is ``False``
bottom : array_like, scalar, or None
Location of the bottom baseline of each bin. If a scalar,
the base line for each bin is shifted by the same amount.
If an array, each bin is shifted independently and the length
of bottom must match the number of bins. If None, defaults to 0.
Default is ``None``
histtype : {'bar', 'barstacked', 'step', 'stepfilled'}, optional
The type of histogram to draw.
- 'bar' is a traditional bar-type histogram. If multiple data
are given the bars are aranged side by side.
- 'barstacked' is a bar-type histogram where multiple
data are stacked on top of each other.
- 'step' generates a lineplot that is by default
unfilled.
- 'stepfilled' generates a lineplot that is by default
filled.
Default is 'bar'
align : {'left', 'mid', 'right'}, optional
Controls how the histogram is plotted.
- 'left': bars are centered on the left bin edges.
- 'mid': bars are centered between the bin edges.
- 'right': bars are centered on the right bin edges.
Default is 'mid'
orientation : {'horizontal', 'vertical'}, optional
If 'horizontal', `~matplotlib.pyplot.barh` will be used for
bar-type histograms and the *bottom* kwarg will be the left edges.
rwidth : scalar or None, optional
The relative width of the bars as a fraction of the bin width. If
`None`, automatically compute the width.
Ignored if `histtype` is 'step' or 'stepfilled'.
Default is ``None``
log : boolean, optional
If `True`, the histogram axis will be set to a log scale. If `log`
is `True` and `x` is a 1D array, empty bins will be filtered out
and only the non-empty (`n`, `bins`, `patches`) will be returned.
Default is ``False``
color : color or array_like of colors or None, optional
Color spec or sequence of color specs, one per dataset. Default
(`None`) uses the standard line color sequence.
Default is ``None``
label : string or None, optional
String, or sequence of strings to match multiple datasets. Bar
charts yield multiple patches per dataset, but only the first gets
the label, so that the legend command will work as expected.
default is ``None``
stacked : boolean, optional
If `True`, multiple data are stacked on top of each other If
`False` multiple data are aranged side by side if histtype is
'bar' or on top of each other if histtype is 'step'
Default is ``False``
Returns
-------
n : array or list of arrays
The values of the histogram bins. See **normed** and **weights**
for a description of the possible semantics. If input **x** is an
array, then this is an array of length **nbins**. If input is a
sequence arrays ``[data1, data2,..]``, then this is a list of
arrays with the values of the histograms for each of the arrays
in the same order.
bins : array
The edges of the bins. Length nbins + 1 (nbins left edges and right
edge of last bin). Always a single array even when multiple data
sets are passed in.
patches : list or list of lists
Silent list of individual patches used to create the histogram
or list of such list if multiple input datasets.
Other Parameters
----------------
kwargs : `~matplotlib.patches.Patch` properties
See also
--------
hist2d : 2D histograms
Notes
-----
Until numpy release 1.5, the underlying numpy histogram function was
incorrect with `normed`=`True` if bin sizes were unequal. MPL
inherited that error. It is now corrected within MPL when using
earlier numpy versions.
Examples
--------
.. plot:: mpl_examples/statistics/histogram_demo_features.py
.. note::
In addition to the above described arguments, this function can take a
**data** keyword argument. If such a **data** argument is given, the
following arguments are replaced by **data[<arg>]**:
* All arguments with the following names: 'weights', 'x'.