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class包：提供Knn()函数

kknn包：提供kknn()函数及miete数据集（房租信息）

kknn函数：实现有权重的K最近邻

knn函数：实现K最近邻算法

klaR包：提供NavieBayes()函数

lda函数：线性判别

MASS包：提供lda()和qda()函数

NavieBayes()函数：实现朴素贝叶斯算法

#####################判别分析#############################
> #读取数据
> library(kknn)
> data("miete")
> head(miete)
       nm wfl     bj bad0 zh ww0 badkach fenster kueche mvdauer bjkat
1  693.29  50 1971.5    0  1   0       0       0      0       2     4
2  736.60  70 1971.5    0  1   0       0       0      0      26     4
3  732.23  50 1971.5    0  1   0       0       0      0       1     4
4 1295.14  55 1893.0    0  1   0       0       0      0       0     1
5  394.97  46 1957.0    0  0   1       0       0      0      27     3
6 1285.64  94 1971.5    0  1   0       1       0      0       2     4
  wflkat      nmqm rooms nmkat adr wohn
1      1 13.865800     1     3   2    2
2      2 10.522857     3     3   2    2
3      1 14.644600     1     3   2    2
4      2 23.548000     3     5   2    2
5      1  8.586304     3     1   2    2
6      3 13.677021     4     5   2    2
> summary(miete)
       nm              wfl               bj       bad0     zh     
 Min.   : 127.1   Min.   : 20.00   Min.   :1800   0:1051   0:202  
 1st Qu.: 543.6   1st Qu.: 50.25   1st Qu.:1934   1:  31   1:880  
 Median : 746.0   Median : 67.00   Median :1957                   
 Mean   : 830.3   Mean   : 69.13   Mean   :1947                   
 3rd Qu.:1030.0   3rd Qu.: 84.00   3rd Qu.:1972                   
 Max.   :3130.0   Max.   :250.00   Max.   :1992                   
 ww0      badkach fenster  kueche     mvdauer      bjkat   wflkat 
 0:1022   0:446   0:1024   0:980   Min.   : 0.00   1:218   1:271  
 1:  60   1:636   1:  58   1:102   1st Qu.: 2.00   2:154   2:513  
                                   Median : 6.00   3:341   3:298  
                                   Mean   :10.63   4:226          
                                   3rd Qu.:17.00   5: 79          
                                   Max.   :82.00   6: 64          
      nmqm            rooms       nmkat   adr      wohn   
 Min.   : 1.573   Min.   :1.000   1:219   1:  25   1: 90  
 1st Qu.: 8.864   1st Qu.:2.000   2:230   2:1035   2:673  
 Median :12.041   Median :3.000   3:210   3:  22   3:319  
 Mean   :12.647   Mean   :2.635   4:208                   
 3rd Qu.:16.135   3rd Qu.:3.000   5:215                   
 Max.   :35.245   Max.   :9.000                           
> #对数据进行分层抽样
> library(sampling)
> n <- round(2/3*nrow(miete)/5)
> n
[1] 144
> sub_train <- strata(miete,stratanames = 'nmkat',size = rep(n,5),method = 'srswor')
> #显示nmkat取值、在数据集中的序号、别抽到的概率、所在层
> head(sub_train)
   nmkat ID_unit      Prob Stratum
1      3       1 0.6857143       1
3      3       3 0.6857143       1
8      3       8 0.6857143       1
20     3      20 0.6857143       1
27     3      27 0.6857143       1
28     3      28 0.6857143       1
> tail(sub_train)
     nmkat ID_unit     Prob Stratum
1058     2    1058 0.626087       5
1061     2    1061 0.626087       5
1062     2    1062 0.626087       5
1064     2    1064 0.626087       5
1067     2    1067 0.626087       5
1080     2    1080 0.626087       5
> #将下面代码就行修改
> #> data_train <- getdata(miete[,c(-1,-3,-12)],sub_train$ID_unit)
> #> data_test <- getdata(miete[,c(-1,-3,-12)],-sub_train$ID_unit)
> #构建训练集和测试集
> # 总的id
> d1<-as.factor(row.names(miete))
> # 训练集的id
> d2<-as.factor(sub_train$ID_unit)
> # 测试集的id
> d3<-as.factor(setdiff(d1,d2))
> # 训练集操作
> t1<-miete[d2,]
> data_train<-t1[,c(-1,-3,-12)]
> # 测试集操作
> t2<-miete[d3,]
> data_test<-t2[,c(-1,-3,-12)]
> dim(data_train);dim(data_test)
[1] 720  14
[1] 362  14
> head(data_test)
    wfl bad0 zh ww0 badkach fenster kueche mvdauer bjkat      nmqm rooms
70   42    0  1   0       0       0      0       6     4 18.270238     2
49   84    0  1   0       1       0      0      12     4 13.004643     4
53   95    0  1   0       0       0      0      40     2  7.581579     4
79   77    0  1   0       1       0      0       3     4  5.006623     3
88   77    0  1   0       0       0      0       1     5  9.405714     3
100  56    0  1   1       0       0      0      35     3  6.822143     2
    nmkat adr wohn
70      3   2    3
49      4   2    2
53      3   2    3
79      1   2    2
88      3   2    2
100     1   2    2
> ############################1.线性判别##########################
> library(MASS)
> fit_lda1 <- lda(nmkat ~.,data_train)
> names(fit_lda1)
 [1] "prior"   "counts"  "means"   "scaling" "lev"     "svd"    
 [7] "N"       "call"    "terms"   "xlevels"
> #各类别的先验概率
> fit_lda1$prior
        1         2         3         4         5 
0.2166667 0.2069444 0.1944444 0.1916667 0.1902778 
> #各类别的样本量
> fit_lda1$counts
  1   2   3   4   5 
156 149 140 138 137 
> #各变量的均值
> fit_lda1$means
       wfl       bad01       zh1       ww01  badkach1   fenster1
1 55.64744 0.076923077 0.5769231 0.16025641 0.4038462 0.04487179
2 60.64430 0.020134228 0.8322148 0.05369128 0.5503356 0.05369128
3 66.70000 0.021428571 0.8214286 0.05000000 0.4857143 0.05714286
4 73.74638 0.007246377 0.8913043 0.05072464 0.6956522 0.03623188
5 91.87591 0.007299270 0.9489051 0.00729927 0.7664234 0.03649635
     kueche1   mvdauer     bjkat.L     bjkat.Q      bjkat.C    bjkat^4
1 0.03846154 15.666667 -0.23598103 -0.11330544  0.053512738 0.15748520
2 0.06711409 11.234899 -0.09545786 -0.18380097 -0.029514096 0.19912893
3 0.05714286 12.350000 -0.11610792 -0.16054602  0.028749445 0.16738427
4 0.11594203  9.507246 -0.05369868 -0.13520021 -0.030786443 0.12187985
5 0.25547445  5.065693 -0.02879018 -0.01831756  0.003808388 0.07862765
       bjkat^5      nmqm    rooms        adr.L      adr.Q     wohn.L
1 -0.113066295  8.384154 2.141026 -0.009065472 -0.7850929 0.10425292
2 -0.038472894 10.892131 2.422819 -0.014237049 -0.7918373 0.10915071
3 -0.032396955 12.326318 2.592857 -0.025253814 -0.7727557 0.09091373
4  0.001369436 14.434710 2.797101  0.015371887 -0.7898717 0.19983453
5 -0.039083918 17.154980 3.321168  0.015484090 -0.7717979 0.29419771
      wohn.Q
1 -0.4003974
2 -0.3972886
3 -0.4315768
4 -0.3816234
5 -0.2532927
> fit_lda1
Call:
lda(nmkat ~ ., data = data_train)

Prior probabilities of groups:
        1         2         3         4         5 
0.2166667 0.2069444 0.1944444 0.1916667 0.1902778 

Group means:
       wfl       bad01       zh1       ww01  badkach1   fenster1
1 55.64744 0.076923077 0.5769231 0.16025641 0.4038462 0.04487179
2 60.64430 0.020134228 0.8322148 0.05369128 0.5503356 0.05369128
3 66.70000 0.021428571 0.8214286 0.05000000 0.4857143 0.05714286
4 73.74638 0.007246377 0.8913043 0.05072464 0.6956522 0.03623188
5 91.87591 0.007299270 0.9489051 0.00729927 0.7664234 0.03649635
     kueche1   mvdauer     bjkat.L     bjkat.Q      bjkat.C    bjkat^4
1 0.03846154 15.666667 -0.23598103 -0.11330544  0.053512738 0.15748520
2 0.06711409 11.234899 -0.09545786 -0.18380097 -0.029514096 0.19912893
3 0.05714286 12.350000 -0.11610792 -0.16054602  0.028749445 0.16738427
4 0.11594203  9.507246 -0.05369868 -0.13520021 -0.030786443 0.12187985
5 0.25547445  5.065693 -0.02879018 -0.01831756  0.003808388 0.07862765
       bjkat^5      nmqm    rooms        adr.L      adr.Q     wohn.L
1 -0.113066295  8.384154 2.141026 -0.009065472 -0.7850929 0.10425292
2 -0.038472894 10.892131 2.422819 -0.014237049 -0.7918373 0.10915071
3 -0.032396955 12.326318 2.592857 -0.025253814 -0.7727557 0.09091373
4  0.001369436 14.434710 2.797101  0.015371887 -0.7898717 0.19983453
5 -0.039083918 17.154980 3.321168  0.015484090 -0.7717979 0.29419771
      wohn.Q
1 -0.4003974
2 -0.3972886
3 -0.4315768
4 -0.3816234
5 -0.2532927

Coefficients of linear discriminants:
                  LD1          LD2         LD3           LD4
wfl       0.060132965  0.026719778  0.01623211 -0.0001588888
bad01     0.183794417  1.618516774  0.19641105 -0.4194358217
zh1       0.144370594 -1.418506813 -0.33062418 -0.4431515370
ww01     -0.312648201  0.378690539 -0.82384090  1.6315813647
badkach1  0.225632434  0.279944241 -1.17357888  0.5486835576
fenster1  0.063422366 -0.430194179  0.53253424 -0.7735389574
kueche1   0.206967799  0.962199352 -0.60661745 -1.3404546843
mvdauer  -0.003722578 -0.005581735  0.02749353  0.0443173127
bjkat.L   0.093612418 -0.238045891 -0.34433616 -0.4090478086
bjkat.Q  -0.126820269  0.351221286  0.01807868 -0.8727242056
bjkat.C  -0.130034438  0.783834929  1.42782762 -0.1273525761
bjkat^4  -0.324588339 -0.230475173  0.17279663 -0.7049687536
bjkat^5  -0.242146129 -0.303624065  0.49681661  0.3164478032
nmqm      0.386251893 -0.011760297  0.08939692  0.1186454076
rooms     0.195274078 -0.601439513 -0.14982530 -0.1564289343
adr.L    -1.629909354  0.670104728 -3.79537471  2.5545277034
adr.Q    -0.645420248  0.169387746  0.57020529  0.4311319766
wohn.L    0.328225174  0.403076098 -0.43450727  0.2871776246
wohn.Q   -0.117194352  0.076668423 -0.28131663 -0.5787510142

Proportion of trace:
   LD1    LD2    LD3    LD4 
0.9750 0.0145 0.0065 0.0040 
> #另一种实现方法
> fit_lda2 <- lda(data_train[,-12],data_train[,12])
> fit_lda2
Call:
lda(data_train[, -12], data_train[, 12])

Prior probabilities of groups:
        1         2         3         4         5 
0.2166667 0.2069444 0.1944444 0.1916667 0.1902778 

Group means:
       wfl     bad0       zh      ww0  badkach  fenster   kueche
1 55.64744 1.076923 1.576923 1.160256 1.403846 1.044872 1.038462
2 60.64430 1.020134 1.832215 1.053691 1.550336 1.053691 1.067114
3 66.70000 1.021429 1.821429 1.050000 1.485714 1.057143 1.057143
4 73.74638 1.007246 1.891304 1.050725 1.695652 1.036232 1.115942
5 91.87591 1.007299 1.948905 1.007299 1.766423 1.036496 1.255474
    mvdauer    bjkat      nmqm    rooms      adr     wohn
1 15.666667 2.512821  8.384154 2.141026 1.987179 2.147436
2 11.234899 3.100671 10.892131 2.422819 1.979866 2.154362
3 12.350000 3.014286 12.326318 2.592857 1.964286 2.128571
4  9.507246 3.275362 14.434710 2.797101 2.021739 2.282609
5  5.065693 3.379562 17.154980 3.321168 2.021898 2.416058

Coefficients of linear discriminants:
                 LD1          LD2         LD3           LD4
wfl      0.058274265  0.026581902 -0.02064524 -0.0001174871
bad0     0.137868576  1.650656213 -0.59096909  0.6018053170
zh       0.136047136 -1.526527081  0.48965931  0.3074164084
ww0     -0.305368459  0.495068681  1.15483610 -1.4958478494
badkach  0.219923203  0.414029221  1.33933838 -0.3203832167
fenster  0.050643136 -0.709690537 -0.48756790  0.7037612341
kueche   0.111668906  1.097164642  0.06409716  1.7493134726
mvdauer -0.004541142 -0.006717243 -0.02226311 -0.0533731169
bjkat    0.017078305 -0.116117354  0.09796824  0.0122905946
nmqm     0.379507938 -0.013211688 -0.06893267 -0.1360574504
rooms    0.209607325 -0.610650914  0.21136687  0.1380030913
adr     -0.940986465  0.721633927  2.96937918 -1.8682410267
wohn     0.201982053  0.443293384  0.40608410  0.2930551074

Proportion of trace:
   LD1    LD2    LD3    LD4 
0.9787 0.0131 0.0050 0.0032 
> #可视化
> plot(fit_lda1)
> #可以看出1,5比较分散，234混在一起
> plot(fit_lda1,dimen=1)
Error in plot.new() : figure margins too large
> #可以看出1,5比较分散，234混在一起
> plot(fit_lda1,dimen=2)
Warning message:
In doTryCatch(return(expr), name, parentenv, handler) :
  display list redraw incomplete
> #进行预测
> pre_lda1 <- predict(fit_lda1,data_test)
> table(pre_lda1$class)

 1  2  3  4  5 
82 80 59 81 60 
> #计算混淆矩阵，正确率为68+45+39+55+53）/362=71.82%
> table(data_test$nmkat,pre_lda1$class)
   
     1  2  3  4  5
  1 68 14  1  1  0
  2 12 45  8  3  0
  3  2 21 39  9  1
  4  0  0 11 55  6
  5  0  0  0 13 53
> #计算错误率：0.281768
> errol_lda1 <- sum(as.numeric(as.numeric(pre_lda1$class)!=as.numeric(data_test$nmkat)))/nrow(data_test)
> errol_lda1
[1] 0.281768
 

> #######################2.朴素贝叶斯########################
> #1.公式formula格式
> library(klaR)
> fit_Bayes1 <- NaiveBayes(nmkat ~.,data_train)
> names(fit_Bayes1)
[1] "apriori"   "tables"    "levels"    "call"      "x"         "usekernel"
[7] "varnames" 
> fit_Bayes1$apriori
grouping
        1         2         3         4         5 
0.2166667 0.2069444 0.1944444 0.1916667 0.1902778 
> #通过分析bad0,0表示有浴室，房租差距不大
> #wohn和adr，1表示环境不好，3表示环境好，3随租金呈上升趋势
> fit_Bayes1$tables
$wfl
      [,1]     [,2]
1 55.64744 24.33842
2 60.64430 20.58472
3 66.70000 20.29449
4 73.74638 23.18226
5 91.87591 31.57751

$bad0
        var
grouping           0           1
       1 0.923076923 0.076923077
       2 0.979865772 0.020134228
       3 0.978571429 0.021428571
       4 0.992753623 0.007246377
       5 0.992700730 0.007299270

......

$rooms
      [,1]      [,2]
1 2.141026 0.9601661
2 2.422819 1.0791714
3 2.592857 0.8724103
4 2.797101 0.9677985
5 3.321168 1.1176019

$adr
        var
grouping           1           2           3
       1 0.019230769 0.974358974 0.006410256
       2 0.020134228 0.979865772 0.000000000
       3 0.035714286 0.964285714 0.000000000
       4 0.000000000 0.978260870 0.021739130
       5 0.007299270 0.963503650 0.029197080

$wohn
        var
grouping          1          2          3
       1 0.09615385 0.66025641 0.24358974
       2 0.09395973 0.65771812 0.24832215
       3 0.09285714 0.68571429 0.22142857
       4 0.03623188 0.64492754 0.31884058
       5 0.02189781 0.54014599 0.43795620

> fit_Bayes1$levels
[1] "1" "2" "3" "4" "5"
> fit_Bayes1$call
NaiveBayes.default(x = X, grouping = Y)
> fit_Bayes1$varnames
 [1] "wfl"     "bad0"    "zh"      "ww0"     "badkach" "fenster" "kueche" 
 [8] "mvdauer" "bjkat"   "nmqm"    "rooms"   "adr"     "wohn"   
> #2.各类别密度下可视化
> plot(fit_Bayes1,vars = 'wf1',n=50,col=c(1,'darkgrey',1,'darkgrey',1))
> plot(fit_Bayes1,vars = 'mvdauer',n=50,col=c(1,'darkgrey',1,'darkgrey',1))
Hit <Return> to see next plot: 

> plot(fit_Bayes1,vars = 'nmqm',n=50,col=c(1,'darkgrey',1,'darkgrey',1))
Hit <Return> to see next plot: 

> #3.默认格式
> fit_Bayes2 <-NaiveBayes(data_train[,-12],data_train[,12])
> #4.对测试集预测
> pre_Bayes1 <- predict(fit_Bayes1,data_test)
There were 50 or more warnings (use warnings() to see the first 50)
> pre_Bayes1
$class
 70  49  53  79  88 100 104 107 112 121 144 151 166 185 205 211 214 221 226 
  4   4   1   2   2   1   1   2   5   1   3   5   4   3   4   1   5   5   1 
.....
 10  11  12  13  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29 
  5   5   5   2   4   4   3   5   5   3   5   2   1   1   2   4   2   3   1 
 30 
  1 
Levels: 1 2 3 4 5

$posterior
               1            2            3            4            5
70  2.416666e-02 2.273255e-01 2.551058e-01 3.240992e-01 1.693029e-01
....
204 5.656179e-02 4.580094e-01 2.514542e-01 1.954695e-01 3.850509e-02
206 7.575586e-05 2.298567e-03 5.326445e-03 1.455069e-01 8.467923e-01
207 8.560613e-03 1.816113e-01 1.722996e-01 5.692817e-01 6.824674e-02
208 8.306373e-03 1.316462e-01 1.547190e-01 3.276939e-01 3.776345e-01
 [ reached getOption("max.print") -- omitted 162 rows ]

> #计算混淆矩阵
> table(data_test$nmkat,pre_Bayes1$class)
   
     1  2  3  4  5
  1 54 26  0  0  4
  2 11 37  9  5  6
  3 11 20 23 12  6
  4  5  1 11 35 20
  5  0  0  3 10 53
> #计算错误率 [1] 0.441989
> errol_Bayes1 <- sum(as.numeric(as.numeric(pre_Bayes1$class)!=as.numeric(data_test$nmkat)))/nrow(data_test)
> errol_Bayes1
[1] 0.441989

> ###########################3.K最近邻####################
> library(class)
> fit_pre_knn <- knn(data_train[,-12],data_test[,-12],cl=data_train[,12])
> fit_pre_knn
  [1] 3 4 3 1 3 1 1 2 2 1 3 5 4 4 4 2 5 3 1 3 2 3 1 1 4 2 1 1 3 1 2 3 2 3 3
 [36] 1 5 1 4 1 4 4 4 5 4 5 3 2 2 3 1 1 1 3 2 1 4 3 2 3 5 3 2 5 1 3 1 1 1 1
 [71] 5 4 2 3 2 5 4 3 4 2 2 1 3 2 3 2 5 2 3 4 4 2 3 2 2 1 1 4 5 3 1 4 3 5 2
[106] 5 1 1 4 2 3 2 1 1 3 4 5 4 5 3 5 1 4 3 2 3 1 1 5 1 4 5 1 2 3 4 4 5 5 1
[141] 2 5 5 5 1 4 2 3 3 5 2 5 3 4 4 1 1 5 5 4 5 3 1 2 5 4 3 2 3 2 1 1 2 2 2
[176] 4 4 2 3 1 2 2 1 1 5 3 4 5 1 2 4 1 5 4 5 2 2 4 4 5 4 4 1 1 2 2 1 2 2 4
[211] 2 1 4 4 1 4 5 2 4 4 3 4 5 4 2 1 4 4 4 5 2 1 4 4 1 1 3 1 5 3 3 3 5 3 2
[246] 4 3 3 2 4 4 1 5 3 3 3 1 1 1 1 2 4 2 1 2 2 5 5 1 1 3 4 4 5 3 3 2 5 5 1
[281] 3 1 1 1 1 4 5 4 1 3 3 3 5 5 4 4 5 5 4 4 1 5 2 5 5 3 2 3 5 5 5 4 4 5 5
[316] 3 4 1 1 3 2 1 3 5 2 2 2 2 1 4 4 1 1 1 3 3 3 5 1 5 3 4 2 5 5 2 4 3 2 5
[351] 5 3 4 3 1 1 1 5 3 3 2 1
Levels: 1 2 3 4 5
> table(data_test$nmkat,fit_pre_knn)
   fit_pre_knn
     1  2  3  4  5
  1 84  0  0  0  0
  2  0 68  0  0  0
  3  0  0 72  0  0
  4  0  0  0 72  0
  5  0  0  0  0 66
> errol_knn <- sum(as.numeric(as.numeric(fit_pre_knn)!=as.numeric(data_test$nmkat)))/nrow(data_test)
> errol_knn
[1] 0
> error_knn = rep(0,20)
> for (i in 1:20) {
+   fit_pre_knn = knn(data_train[,-12],data_test[,-12],cl=data_train[,12],k=i)
+   errol_knn[i] =sum(as.numeric(as.numeric(fit_pre_knn)!=as.numeric(data_test$nmkat)))/nrow(data_test)
+ }
> errol_knn
 [1] 0.0000000 0.1629834 0.1353591 0.1850829 0.1546961 0.1823204 0.1767956
 [8] 0.1906077 0.2209945 0.2320442 0.2458564 0.2679558 0.2596685 0.2651934
[15] 0.2734807 0.2734807 0.3038674 0.2928177 0.3232044 0.3259669
> plot(errol_knn,type = 'l',xlab = 'K')

> ######有权重的K####
> library('kknn')
> fit_pre_kknn <- kknn(nmkat~.,data_train,data_test[,-12],k=5)
> #fit为判定结果
> summary(fit_pre_kknn)

Call:
kknn(formula = nmkat ~ ., train = data_train, test = data_test[,     -12], k = 5)

Response: "ordinal"
    fit     prob.1     prob.2     prob.3     prob.4 prob.5
1     3 0.00000000 0.25672296 0.76636967 1.00000000      1
2     4 0.00000000 0.00000000 0.02451458 1.00000000      1
3     3 0.00000000 0.08072417 0.74327704 0.74327704      1
4     1 0.56585629 0.97548542 1.00000000 1.00000000      1
.....
163   2 0.48513212 1.00000000 1.00000000 1.00000000      1
164   2 0.00000000 0.97548542 0.97548542 1.00000000      1
165   4 0.00000000 0.00000000 0.40962913 0.51486788      1
166   4 0.00000000 0.08072417 0.33744713 0.82257926      1
 [ reached 'max' / getOption("max.print") -- omitted 196 rows ]
> fit <- fitted(fit_pre_kknn)
> fit
  [1] 3 4 3 1 3 1 1 2 2 1 3 4 4 3 4 2 5 3 3 3 3 3 1 1 4 2 1 1 3 2 2 3 2 3 3
 [36] 1 5 1 4 3 4 4 4 5 4 5 3 2 2 3 1 2 1 3 1 1 4 3 2 3 5 3 2 5 2 3 1 1 1 1
 [71] 5 3 2 3 2 5 4 3 4 2 2 2 3 2 3 2 5 2 3 4 4 2 3 2 2 1 1 4 5 3 1 3 2 5 2
[106] 5 1 1 4 2 3 2 3 1 2 4 5 4 5 3 5 2 4 3 2 3 1 1 5 1 4 5 2 2 2 4 4 5 5 1
[141] 2 5 5 5 1 4 2 4 3 5 1 5 3 3 4 1 2 5 5 4 5 3 2 2 4 4 3 2 3 2 1 1 2 2 2
[176] 4 4 2 3 1 2 3 1 1 5 4 4 5 1 4 4 1 5 4 5 2 2 4 4 5 4 4 1 1 2 2 1 2 2 4
[211] 2 1 3 4 1 4 5 2 3 4 3 4 5 4 2 1 4 4 4 4 2 1 4 4 1 1 3 1 5 3 3 3 5 3 2
[246] 4 3 3 1 4 4 1 4 3 3 3 1 1 1 1 3 4 2 1 1 2 5 5 1 1 2 4 4 5 3 3 2 5 5 1
[281] 3 1 1 1 1 4 5 4 1 2 3 1 5 5 4 4 5 5 4 4 1 4 2 5 5 3 2 3 5 3 5 4 4 5 5
[316] 3 3 1 1 3 2 1 4 5 2 2 2 2 1 4 2 1 2 1 3 3 3 5 1 5 3 4 2 5 5 2 4 3 2 5
[351] 5 3 4 3 1 1 1 5 3 3 2 1
Levels: 1 < 2 < 3 < 4 < 5
> table(data_test$nmkat,fit)
   fit
     1  2  3  4  5
  1 72  9  3  0  0
  2  4 60  3  1  0
  3  1  5 63  3  0
  4  0  1  7 64  0
  5  0  0  1  5 60
> errol_kknn <- sum(as.numeric(as.numeric(fit)!=as.numeric(data_test$nmkat)))/nrow(data_test)
> errol_kknn
[1] 0.1187845

> ###############推荐系统综合实例#####################

数据集地址：https://grouplens.org/datasets/movielens/100k/ 选择ml-100K.zip

> data <- read.csv("G:\\R语言\\大三下半年\\数据挖掘：R语言实战\\数据挖掘：R语言实战（案例数据集）\\ml-100k\\movie.csv",header=F)
> data <- data[,-4]
> names(data) <- c('userid','itemid','rating')
> head(data);dim(data)
  userid itemid rating
1    196    242      3
2    186    302      3
3     22    377      1
4    244     51      2
5    166    346      1
6    298    474      4
[1] 100000      3
> ##编写函数
> MovieLnes_KNN=function(Userid,Itemid,n,K)#编写一个总函数可以反复使用
+ {
+   sub=which(data$userid==Userid)#获取待测用户在数据集中各条信息所在的行标签，存于sub
+   if(length(sub)>=n)
+     sun_n=sample(sub,n)
+   if(length(sub)<n)
+     sun_n=sample(sub,length(sub))#随机抽取n个已评分的电影ID
+   known_itemid=data$itemid[sun_n]#获取已评分电影的ID
+   unknown_itemid=Itemid#获取带预测电影的ID
+   known_itemid
+   unknown_itemid
+   unknown_sub=which(data$itemid==unknown_itemid)
+   user=data$userid[unknown_sub[-1]]#获取已评价电影的用户ID
+   user
+   data_all=matrix(0,1+length(user),2+length(known_itemid))#设置data.all的行数、列数，所有值暂取0
+   data_all=data.frame(data_all)
+   names(data_all)=c("userid",paste("unknown_itemid_",Itemid),paste("itemid_",known_itemid,sep=""))
+   item=c(unknown_itemid,known_itemid)
+   data_all$userid=c(Userid,user)#对变量赋值
+   data_all
+   for(i in 1:nrow(data_all))#对data_all按行进行外层循环
+   {
+     data_temp=data[which(data$userid==data_all$userid[i]),]
+     for(j in 1:length(item))#对data—all按列进行内层循环
+     {if(sum(as.numeric(data_temp$itemid==item[j]))!=0)#判断该位置是否有取值
+     {data_all[i,j+1]=data_temp$rating[which(data_temp$itemid==item[j])]
+     }
+     }
+   }
+   data_all
+   data_test_x=data_all[1,c(-1,-2)]#获取测试集的已知部分
+   data_test_y=data_all[1,2]#获取测试集的待预测值
+   data_train_x=data_all[-1,c(-1,-2)]#获取训练集的已知部分
+   data_train_y=data_all[-1,2]#获取训练集的待预测值
+   dim(data_test_x);length(data_test_y)
+   dim(data_train_x);length(data_train_y)
+   fit=knn(data_train_x,data_test_x,cl=data_train_y,k=K)#进行knn判别
+   list("data_all:"=data_all,"True Rating:"=data_test_y,"Predcit Rating:"=fit,"User ID:"=Userid,"Item ID:"=Itemid)
+ }

#用户1对20部电影的评分
> user1=NULL
> for(Item in 1:20)
+ user1=c(user1,MovieLnes_KNN(Userid=1,Itemid=Item,n=50,K=10)$'True Rating:')
Warning message:
In knn(data_train_x, data_test_x, cl = data_train_y, k = K) :
  k = 10 exceeds number 9 of patterns
> user1
 [1] 5 3 4 3 3 5 4 1 5 3 2 5 5 5 5 5 3 4 5 4

#显示评分为5的电影
> which(user1==5)
[1]  1  6  9 12 13 14 15 16 19