Matlab中hist、 histc、bar函数的用法及区别：

首先给出matlab帮助文件的介绍：

Histc

Syntax

1.bincounts = histc(x,binranges)

2.bincounts = histc(x,binranges,dim)

3.[bincounts,ind]= histc(___)

Description

bincounts= histc(x,binranges) counts the number of values in x that are within each specified bin range. Theinput, binranges, determines the endpoints for each bin.The output, bincounts, contains the number of elements from x in each bin.

·        If x is a vector, then histc returns bincounts as a vector of histogram bin counts.

·        If x is a matrix, then histc operates along each column of x and returns bincounts as a matrix of histogram bin counts for eachcolumn.

计算x中的值在每一个箱子(bin)中的个数，binranges决定了每个箱子的端点，也就是划分区间的端点。如果x是向量，那么返回一个向量各个区间有多少个数落在此区间的向量。如果x是矩阵，则对x的每一列进行计算，并返回一个矩阵，对应每一列中位于相应区间的值的个数。因此，如果是想计算整个矩阵中位于某一区间的个数，则把输出矩阵行相加即可。

To plot the histogram, use bar(binranges,bincounts,'histc').

bincounts =histc(x,binranges,dim) operates along the dimension dim.

比上一个多了一个参数‘dim’，指定处理的方向，即1是按列处理，2是按行处理。

[bincounts,ind]=histc(___) returns ind, an array the same size as x indicating the bin number that each entry in x sorts into. Use this syntax with any of theprevious input argument combinations.

这个用法多出来个‘ind’输出参数，该参数指明x的值落入了那个箱子(箱子号)，其长度与x的产生过度一致。

那么问题来了，histc的箱子是怎么划分区间的，就是那边是闭区间，那边是开区间。测试：

>> range=1:5

range =  1     2    3     4     5

>> aa

aa = 1     2     2    2     3     4    4     5     5    5     5     5    5

>> [i1,i2]=histc(aa,range)

i1 =  1     3     1    2     6

i2 =1    2     2     2    3     4     4    5     5     5    5     5     5

可以发现histc的5区间（箱子）的划分为

[1,2)，[2,3)，[3,4)，[4,5)，[5,inf)

hist

Syntax

·        hist(data)example

·        hist(data,nbins)example

·        hist(data,xvalues)example

·        hist(axes_handle,___)example

·        nelements= hist(___)

·        [nelements,centers]= hist(___)example

Description

hist(data) creates a histogram bar plot of data. Elements in data are sorted into 10 equally spaced

bins along the x-axis between the minimum and maximum values ofdata. Bins are displayed as rectangles such that the heightof each rectangle indicates the number of elements in the bin.

等间隔划分对max(data)- min(data)的值进行10等间隔划分并作图

hist(data,nbins) sorts data into the number of bins specified by the scalar nbins.

对data进行制定nbins的区间进行等间隔划分并作图。

hist(data,xvalues) sorts data into bins with intervals determined by the vector xvalues.

·        If xvalues is a vector of evenly spaced values,then hist uses the values as the bin centers.

·        If xvalues is a vector unevenly spaced values,then hist uses the midpoints betweenconsecutive values as the bin edges.

The length of the vector, length(xvalues), determines the number of bins.

如果xvalues是均匀的，则hist使用xvalues值作为边界的中心

如果xvalues 是非均匀的，则hist使用连续的边界值的中值作为中心

hist(axes_handle,___) plots into the axes specified by axes_handle instead of into the current axes (gca). The option axes_handle can precede any of the input argument combinationsin the previous syntaxes.

nelements =hist(___) returns a row vector, nelements, indicating the number of elements in each bin.

返回一个行矢量，矢量中的每一个值指明了每个区间中的值的个数

[nelements,centers]= hist(___) returns an additional row vector, centers, indicating the location of each bincenter on the x-axis. To plot the histogram, youcan usebar(centers,nelements).

‘centers’指明了每个区间的中值

bar

Syntax

·        bar(Y)example

·        bar(x,Y)example

·        bar(___,width)example

·        bar(___,style)example

·        bar(___,bar_color)example

·        bar(___,Name,Value)example

·        bar(axes_handle,___)example

·        h = bar(___)

Description

bar(Y) draws one bar for each element in Y.

绘制Y中的每一个元素在一个柱中

y = [75.995,91.972,105.711,123.203,131.669,...

150.697,179.323,203.212,226.505,249.633,281.422];

figure;

bar(y)

bar(x,Y) draws bars for each column in Y at locations specified in x.

‘x’指定了绘制Y的每一列数据的位置

bar(___,width) sets the relative bar width andcontrols the separation of bars within a group and can include any of the inputarguments in previous syntaxes.

定义了每个bar的宽度

bar(___,style) specifies the style of the bars andcan include any of the input arguments in previous syntaxes.

定义bar的样式

Y = round(rand(5,3)*10); figure; subplot(2,2,1); bar(Y,'grouped'); title('Group') subplot(2,2,2); bar(Y,'stacked'); title('Stack') subplot(2,2,3); bar(Y,'histc'); title('Histc') subplot(2,2,4); bar(Y,'hist'); title('Hist')

bar(___,bar_color) displays all bars using the colorspecified by the single-letter abbreviation of bar_color and can include any of the input arguments inprevious syntaxes.

定义了bar图形的填充色

y = [75.995,91.972,105.711,123.203,131.669,...      150.697,179.323,203.212,226.505,249.633,281.422]; figure; bar(y,'r');

bar(___,Name,Value) sets the property names to thespecified values and can include any of the input arguments in previoussyntaxes.

设定属性名为‘Name’的‘Value’

Note:   You cannot specify names and values when using hist or histc options.

y = [75.995,91.972,105.711,123.203,131.669,...      150.697,179.323,203.212,226.505,249.633,281.422]; figure; bar(y,'g','EdgeColor',[1,0.5,0.5]);

bar(axes_handle,___) plots into the axes with the handle axes_handle instead of into the current axes (gca).

把图绘制到指定的句柄图形