Der*_*ang 24 r classification svm
我是R的新手,我在R中使用该e1071软件包进行SVM分类.
我使用了以下代码:
data <- loadNumerical()
model <- svm(data[,-ncol(data)], data[,ncol(data)], gamma=10)
print(predict(model, data[c(1:20),-ncol(data)]))
的loadNumerical是用于装载数据,并且将数据的形式为(第一8列被输入并且最后一列是分类):
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9]
1 39 1 -1 43 -1 1 0 0.9050497 0
2 23 -1 -1 30 -1 -1 0 1.6624974 1
3 50 -1 -1 49 1 1 2 1.5571429 0
4 46 -1 1 19 -1 -1 0 1.3523685 0
5 36 1 1 29 -1 1 1 1.3812029 1
6 27 -1 -1 19 1 1 0 1.9403649 0
7 36 -1 -1 25 -1 1 0 2.3360004 0
8 41 1 1 23 1 -1 1 2.4899738 0
9 21 -1 -1 18 1 -1 2 1.2989637 1
10 39 -1 1 21 -1 -1 1 1.6121595 0
数据中的行数为500.
如上面的代码所示,我测试了前20行进行预测.输出是:
1 2 3 4 5 6 7
0.04906014 0.88230392 0.04910760 0.04910719 0.87302217 0.04898187 0.04909523
8 9 10 11 12 13 14
0.04909199 0.87224979 0.04913189 0.04893709 0.87812890 0.04909588 0.04910999
15 16 17 18 19 20
0.89837037 0.04903778 0.04914173 0.04897789 0.87572114 0.87001066
我可以直观地从结果中看出,当结果接近0时,它意味着0级,如果它接近1,则它在1级中.
但我的问题是如何才能准确地解释结果:我可以使用一个阈值s,以便将低于s的值归类为0,将高于s的值归类为1？
如果存在这样的s,我该如何得出它？
Ian*_*ows 34
由于结果变量是数字,因此它使用SVM的回归公式.我想你想要分类表达.您可以通过将结果强制转换为因子或设置来更改此设置type="C-classification".
回归:
> model <- svm(vs ~ hp+mpg+gear,data=mtcars)
> predict(model)
Mazda RX4 Mazda RX4 Wag Datsun 710 Hornet 4 Drive
0.8529506670 0.8529506670 0.9558654451 0.8423224174
Hornet Sportabout Valiant Duster 360 Merc 240D
0.0747730699 0.6952501964 0.0123405904 0.9966162477
Merc 230 Merc 280 Merc 280C Merc 450SE
0.9494836511 0.7297563543 0.6909235343 -0.0327165348
Merc 450SL Merc 450SLC Cadillac Fleetwood Lincoln Continental
-0.0092851098 -0.0504982402 0.0319974842 0.0504292348
Chrysler Imperial Fiat 128 Honda Civic Toyota Corolla
-0.0504750284 0.9769206963 0.9724676874 0.9494910097
Toyota Corona Dodge Challenger AMC Javelin Camaro Z28
0.9496260289 0.1349744908 0.1251344111 0.0395243313
Pontiac Firebird Fiat X1-9 Porsche 914-2 Lotus Europa
0.0983094417 1.0041732099 0.4348209129 0.6349628695
Ford Pantera L Ferrari Dino Maserati Bora Volvo 142E
0.0009258333 0.0607896408 0.0507385269 0.8664157985
分类:
> model <- svm(as.factor(vs) ~ hp+mpg+gear,data=mtcars)
> predict(model)
Mazda RX4 Mazda RX4 Wag Datsun 710 Hornet 4 Drive
1 1 1 1
Hornet Sportabout Valiant Duster 360 Merc 240D
0 1 0 1
Merc 230 Merc 280 Merc 280C Merc 450SE
1 1 1 0
Merc 450SL Merc 450SLC Cadillac Fleetwood Lincoln Continental
0 0 0 0
Chrysler Imperial Fiat 128 Honda Civic Toyota Corolla
0 1 1 1
Toyota Corona Dodge Challenger AMC Javelin Camaro Z28
1 0 0 0
Pontiac Firebird Fiat X1-9 Porsche 914-2 Lotus Europa
0 1 0 1
Ford Pantera L Ferrari Dino Maserati Bora Volvo 142E
0 0 0 1
Levels: 0 1
此外,如果您希望将概率作为预测而不仅仅是原始分类,则可以通过拟合概率选项来实现.
有概率:
> model <- svm(as.factor(vs) ~ hp+mpg+gear,data=mtcars,probability=TRUE)
> predict(model,mtcars,probability=TRUE)
Mazda RX4 Mazda RX4 Wag Datsun 710 Hornet 4 Drive
1 1 1 1
Hornet Sportabout Valiant Duster 360 Merc 240D
0 1 0 1
Merc 230 Merc 280 Merc 280C Merc 450SE
1 1 1 0
Merc 450SL Merc 450SLC Cadillac Fleetwood Lincoln Continental
0 0 0 0
Chrysler Imperial Fiat 128 Honda Civic Toyota Corolla
0 1 1 1
Toyota Corona Dodge Challenger AMC Javelin Camaro Z28
1 0 0 0
Pontiac Firebird Fiat X1-9 Porsche 914-2 Lotus Europa
0 1 0 1
Ford Pantera L Ferrari Dino Maserati Bora Volvo 142E
0 0 0 1
attr(,"probabilities")
0 1
Mazda RX4 0.2393753 0.76062473
Mazda RX4 Wag 0.2393753 0.76062473
Datsun 710 0.1750089 0.82499108
Hornet 4 Drive 0.2370382 0.76296179
Hornet Sportabout 0.8519490 0.14805103
Valiant 0.3696019 0.63039810
Duster 360 0.9236825 0.07631748
Merc 240D 0.1564898 0.84351021
Merc 230 0.1780135 0.82198650
Merc 280 0.3402143 0.65978567
Merc 280C 0.3829336 0.61706640
Merc 450SE 0.9110862 0.08891378
Merc 450SL 0.8979497 0.10205025
Merc 450SLC 0.9223868 0.07761324
Cadillac Fleetwood 0.9187301 0.08126994
Lincoln Continental 0.9153549 0.08464509
Chrysler Imperial 0.9358186 0.06418140
Fiat 128 0.1627969 0.83720313
Honda Civic 0.1649799 0.83502008
Toyota Corolla 0.1781531 0.82184689
Toyota Corona 0.1780519 0.82194807
Dodge Challenger 0.8427087 0.15729129
AMC Javelin 0.8496198 0.15038021
Camaro Z28 0.9190294 0.08097056
Pontiac Firebird 0.8361349 0.16386511
Fiat X1-9 0.1490934 0.85090660
Porsche 914-2 0.5797194 0.42028060
Lotus Europa 0.4169587 0.58304133
Ford Pantera L 0.8731716 0.12682843
Ferrari Dino 0.8392372 0.16076281
Maserati Bora 0.8519422 0.14805785
Volvo 142E 0.2289231 0.77107694