Parameters: 

x : (n,) array or sequence of (n,) arrays 
Input values, this takes either a single array or a sequence of arrays which are not required to be of the same length. 
bins : int or sequence or str, optional 
If an integer is given, bins + 1 bin edges are calculated and returned, consistent with numpy.histogram . If bins is a sequence, gives bin edges, including left edge of first bin and right edge of last bin. In this case, bins is returned unmodified. All but the last (righthandmost) bin is halfopen. In other words, if bins is: [1, 2, 3, 4]
then the first bin is [1, 2) (including 1, but excluding 2) and the second [2, 3) . The last bin, however, is [3, 4] , which includes 4. Unequally spaced bins are supported if bins is a sequence. With Numpy 1.11 or newer, you can alternatively provide a string describing a binning strategy, such as 'auto', 'sturges', 'fd', 'doane', 'scott', 'rice', 'sturges' or 'sqrt', see numpy.histogram . The default is taken from rcParams["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 
density : bool, optional 
If True , the first element of the return tuple will be the counts normalized to form a probability density, i.e., the area (or integral) under the histogram will sum to 1. This is achieved by dividing the count by the number of observations times the bin width and not dividing by the total number of observations. If stacked is also True , the sum of the histograms is normalized to 1. Default is None for both normed and density. If either is set, then that value will be used. If neither are set, then the args will be treated as False . If both density and normed are set an error is raised. 
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 or density is True , the weights are normalized, so that the integral of the density over the range remains 1. Default is None 
cumulative : bool, 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 or density 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 and/or density 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 bartype histogram. If multiple data are given the bars are arranged side by side.
 'barstacked' is a bartype 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', barh will be used for bartype 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 : bool, 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 nonempty (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 : str 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 : bool, optional 
If True , multiple data are stacked on top of each other If False multiple data are arranged side by side if histtype is 'bar' or on top of each other if histtype is 'step' Default is False 
normed : bool, optional 
Deprecated; use the density keyword argument instead. 