mean 平均数
median 中位数
mode 众数
prctile 四分位数，也称四分位点，是指在统计学中把所有数值由小到大排列并分成四等份，处于三个分割点位置的数值
>> load stockreturns
>> x4=stocks(:,4)
x4 =
2.9914
2.6204
-0.3624
2.2094
-2.4079
2.9277
-1.0281
-3.3567
1.9482
2.3593
3.5894
-0.8645
-2.1599
-3.8850
-0.3494
-0.8930
1.7893
-0.7141
-1.2013
-3.3592
0.6673
3.7411
2.1308
2.6651
0.9303
-1.6121
0.4302
2.4841
-1.9898
4.5561
2.5903
-0.1640
1.3072
-0.4932
-4.1415
-0.1348
3.2650
-3.1646
-0.6340
-0.7101
-4.3216
0.6100
-1.5280
0.2114
-1.4884
0.9389
1.1603
-0.0880
-2.7591
3.3299
-0.2885
2.2003
-4.3053
0.4916
0.4022
-0.9178
-5.8764
-5.4219
2.9621
-3.1092
2.1127
0.8175
-2.1854
0.6762
0.4983
6.4692
0.7895
2.4106
0.6763
-2.7782
-1.6733
-0.2882
-2.2267
-1.2758
-2.3091
1.4615
-1.2334
-1.2778
1.9237
-1.3201
0.4338
0.5043
-1.7769
1.5579
2.9013
1.1645
-0.6437
1.6442
-0.8432
-0.4492
-2.8875
1.0591
-2.0462
3.6961
3.9568
-5.0162
0.3851
0.5334
1.4381
-0.7173
>> ex.mean=mean(x4)
ex =
包含以下字段的 struct:
mean: -5.8728e-04
>> ex.median=median(x4)
ex =
包含以下字段的 struct:
mean: -5.8728e-04
median: 0.0617
>> ex.mode=mode(x4)
ex =
包含以下字段的 struct:
mean: -5.8728e-04
median: 0.0617
mode: -5.8764
>> ex
ex =
包含以下字段的 struct:
mean: -5.8728e-04
median: 0.0617
mode: -5.8764
x=1:14; freqy=[1 0 1 0 4 0 1 0 3 1 0 0 1 1];%频数 subplot(1,3,1);bar(x,freqy);xlim([0 15]); subplot(1,3,2);area(x,freqy);xlim([0 15]); subplot(1,3,3);stem(x,freqy);xlim([0 15]);
boxplot
%boxplot marks=[80 81 81 84 88 92 92 94 96 97]; boxplot(marks); prctile(marks,[25 50 75]);%prctile百分数 25% 50% 75%
skewness偏度系数
X = randn 返回一个从标准正态分布中得到的随机标量。
>> x=randn([10 3])*3;
x(x(:,1)<0,1)=0;
x(x(:,3)>0,3)=0;
boxplot(x,{'Right-skewed','Symmetric','Left-skewed'});
y=skewness(x)
y =
0.6710 0.9900 -1.4245
下面的东西感觉暂时用不上，先不看了。。