如何在MATLAB神经网络中输入新数据?

我一直在学习神经网络,并试图利用MATLAB的神经网络工具箱和Mathworks提供的示例。我发现这个主题到目前为止非常有趣。

我对MATLAB代码有基本的了解。然而,我在理解如何在神经网络训练完成后输入自己的测试数据方面遇到了困难。Mathworks的所有示例似乎在网络训练完成后就结束了。

例如: http://in.mathworks.com/help/nnet/examples/wine-classification.html#zmw57dd0e324

在上面的链接中有一个“测试神经网络”的部分,但没有提供关于所使用的测试数据的信息。

我知道这可能是一个新手问题,但我很感激任何能帮助我理解这一点的帮助。


回答:

您可以使用神经网络工具箱中的sim命令。基本操作是提交一个M x N矩阵,其中M是特征总数,N是样本总数。M与您拥有的输入层神经元总数相关。因此,对于每个输入,您需要在矩阵中提供一列数据。

因此,一旦您训练了网络,并且如果您遵循示例,您的神经网络应该存储在net中。只要创建您的输入数据,并使用您期望的输入“模拟”神经网络即可。

因此,如果您的输入数据存储在X中,您可以这样做:

Y = sim(net, X);

然而,如果您想查看神经网络在相同输入下的表现,可以尝试使用变量x,因为在帖子中提到的数据集中,输入数据存储在x中:

Y = sim(net, x);

或者,net是一个可调用的对象。您可以通过直接使用net对象来实现与sim相同的效果:

Y = net(x);

如果您想进行一个小测试,可以尝试加载房价数据集:

[x,t] = house_dataset;

这将返回一个包含13个特征(行)的数据矩阵,共有506个样本。这些数据存储在矩阵x中。向量t是输出层的值,或者是通过神经网络运行后的目标值。您可以使用一个具有10个神经元的隐藏层的网络来训练这个数据集的神经网络,然后我们可以看到神经网络在相同输入数据下的表现如何:

net = feedforwardnet(10);net = train(net, x, t); %// 打开神经网络训练工具并训练y = sim(net, x); %// 或者 y = net(x);

然后,您可以并排显示结果并进行比较

disp([y; t]);

顶行是预测值,底行是真实值:

  Columns 1 through 7   23.1000   22.5739   34.6595   32.9133   33.3979   24.0131   19.6418   24.0000   21.6000   34.7000   33.4000   36.2000   28.7000   22.9000  Columns 8 through 14   19.3123   15.3914   18.8765   19.6154   18.8690   20.0817   18.0593   27.1000   16.5000   18.9000   15.0000   18.9000   21.7000   20.4000  Columns 15 through 21   17.4043   17.7989   19.4390   17.8489   18.5007   17.3547   14.3393   18.2000   19.9000   23.1000   17.5000   20.2000   18.2000   13.6000  Columns 22 through 28   16.9866   17.5983   15.2679   16.3294   13.2075   15.6425   14.3992   19.6000   15.2000   14.5000   15.6000   13.9000   16.6000   14.8000  Columns 29 through 35   18.8453   20.4586   14.5208   15.4776   12.6204   14.5306   12.2213   18.4000   21.0000   12.7000   14.5000   13.2000   13.1000   13.5000  Columns 36 through 42   21.5945   21.7292   21.3951   22.8980   29.5480   35.4459   33.3658   18.9000   20.0000   21.0000   24.7000   30.8000   34.9000   26.6000  Columns 43 through 49   24.9201   25.2191   22.0473   20.2307   21.9648   19.1073   16.4167   25.3000   24.7000   21.2000   19.3000   20.0000   16.6000   14.4000  Columns 50 through 56   19.1333   19.4673   19.6465   26.6304   20.6860   18.0080   34.7084   19.4000   19.7000   20.5000   25.0000   23.4000   18.9000   35.4000  Columns 57 through 63   23.9052   28.8725   23.2335   21.1107   18.5425   17.7766   22.5957   24.7000   31.6000   23.3000   19.6000   18.7000   16.0000   22.2000  Columns 64 through 70   24.6137   30.3093   24.5964   20.3996   21.0408   18.2597   19.9876   25.0000   33.0000   23.5000   19.4000   22.0000   17.4000   20.9000  Columns 71 through 77   25.4133   21.4175   22.4705   24.1181   25.2216   22.2482   20.4357   24.2000   21.7000   22.8000   23.4000   24.1000   21.4000   20.0000  Columns 78 through 84   21.7641   20.8850   20.6352   27.3050   22.6721   23.7894   21.7782   20.8000   21.2000   20.3000   28.0000   23.9000   24.8000   22.9000  Columns 85 through 91   24.1746   26.2748   22.9204   23.2649   27.7500   30.4014   23.7201   23.9000   26.6000   22.5000   22.2000   23.6000   28.7000   22.6000  Columns 92 through 98   23.1654   24.7010   25.0065   20.9675   26.6610   22.2313   41.1054   22.0000   22.9000   25.0000   20.6000   28.4000   21.4000   38.7000  Columns 99 through 105   43.3199   33.8214   22.5828   23.9000   19.4996   19.0978   19.2686   43.8000   33.2000   27.5000   26.5000   18.6000   19.3000   20.1000  Columns 106 through 112   17.6835   18.1297   19.9324   19.4827   18.8635   22.3501   23.0958   19.5000   19.5000   20.4000   19.8000   19.4000   21.7000   22.8000  Columns 113 through 119   19.2355   19.4148   21.4072   18.6230   21.0624   19.4977   19.8504   18.8000   18.7000   18.5000   18.3000   21.2000   19.2000   20.4000  Columns 120 through 126   19.7301   22.3515   21.7456   19.6909   17.3642   18.6674   21.4590   19.3000   22.0000   20.3000   20.5000   17.3000   18.8000   21.4000  Columns 127 through 133   15.7843   14.9932   19.6013   14.6810   19.5595   18.3563   18.6026   15.7000   16.2000   18.0000   14.3000   19.2000   19.6000   23.0000  Columns 134 through 140   15.2750   11.8104   18.7860   16.7552   19.7692   15.9850   17.8815   18.4000   15.6000   18.1000   17.4000   17.1000   13.3000   17.8000  Columns 141 through 147   18.1044   11.2998   13.7603   16.7915   14.2739   15.8247   12.1940   14.0000   14.4000   13.4000   15.6000   11.8000   13.8000   15.6000  Columns 148 through 154   14.8796   15.9726   17.0902   20.0606   12.5238   15.0568   15.3508   14.6000   17.8000   15.4000   21.5000   19.6000   15.3000   19.4000  Columns 155 through 161   16.8791   17.1680    7.5081   38.1429   27.6726   23.4515   33.1939   17.0000   15.6000   13.1000   41.3000   24.3000   23.3000   27.0000  Columns 162 through 168   49.9039   49.8868   49.4694   20.0338   20.5124   51.1646   19.0164   50.0000   50.0000   50.0000   22.7000   25.0000   50.0000   23.8000  Columns 169 through 175   23.1614   23.9231   18.1501   19.0578   24.0764   25.6909   24.2217   23.8000   22.3000   17.4000   19.1000   23.1000   23.6000   22.6000  Columns 176 through 182   29.0459   23.7307   24.3887   28.9583   36.7788   41.2092   29.0054   29.4000   23.2000   24.6000   29.9000   37.2000   39.8000   36.2000  Columns 183 through 189   36.1596   29.3311   24.9179   26.8610   46.6416   30.5403   29.2822   37.9000   32.5000   26.4000   29.6000   50.0000   32.0000   29.8000  Columns 190 through 196   32.3537   30.5739   28.0238   33.5408   32.5201   30.3314   47.7960   34.9000   37.0000   30.5000   36.4000   31.1000   29.1000   50.0000  Columns 197 through 203   35.5760   29.9340   32.4614   23.7173   24.6185   22.3271   40.2040   33.3000   30.3000   34.6000   34.9000   32.9000   24.1000   42.3000  Columns 204 through 210   48.7640   51.9776   21.6903   23.1472   19.7713   20.8484   19.3971   48.5000   50.0000   22.6000   24.4000   22.5000   24.4000   20.0000  Columns 211 through 217   19.2595   20.7310   21.9656   24.4268   23.4818   22.6366   23.3319   21.7000   19.3000   22.4000   28.1000   23.7000   25.0000   23.3000  Columns 218 through 224   27.5792   19.9003   21.9243   27.6622   25.8529   27.0425   26.9247   28.7000   21.5000   23.0000   26.7000   21.7000   27.5000   30.1000  Columns 225 through 231   43.9926   46.3891   41.9625   31.2884   42.9222   31.0752   24.0971   44.8000   50.0000   37.6000   31.6000   46.7000   31.5000   24.3000  Columns 232 through 238   33.9499   45.8143   44.0646   27.7080   24.5834   24.8484   33.5038   31.7000   41.7000   48.3000   29.0000   24.0000   25.1000   31.5000  Columns 239 through 245   27.1918   25.1814   24.1256   18.9528   20.8431   27.5930   15.9916   23.7000   23.3000   22.0000   20.1000   22.2000   23.7000   17.6000  Columns 246 through 252   15.4457   21.3048   18.9629   22.2684   26.9249   26.6310   28.3915   18.5000   24.3000   20.5000   24.5000   26.2000   24.4000   24.8000  Columns 253 through 259   31.1707   42.3749   21.8852   20.0264   41.3473   51.4709   37.5230   29.6000   42.8000   21.9000   20.9000   44.0000   50.0000   36.0000  Columns 260 through 266   31.7275   35.0836   40.2452   48.8115   34.8549   36.0551   21.6751   30.1000   33.8000   43.1000   48.8000   31.0000   36.5000   22.8000  Columns 267 through 273   30.0784   48.2556   43.5570   21.8858   19.8884   23.6277   24.2718   30.7000   50.0000   43.5000   20.7000   21.1000   25.2000   24.4000  Columns 274 through 280   36.2902   33.7512   31.2525   32.4099   33.0711   26.3885   36.7014   35.2000   32.4000   32.0000   33.2000   33.1000   29.1000   35.1000  Columns 281 through 287   45.9504   36.7908   46.8473   51.1511   31.4501   23.5448   21.8759   45.4000   35.4000   46.0000   50.0000   32.2000   22.0000   20.1000  Columns 288 through 294   23.4287   22.6450   25.2664   32.6864   35.8508   30.2136   23.6842   23.2000   22.3000   24.8000   28.5000   37.3000   27.9000   23.9000  Columns 295 through 301   21.9361   29.8485   27.2524   20.1174   23.8767   30.0819   26.0127   21.7000   28.6000   27.1000   20.3000   22.5000   29.0000   24.8000  Columns 302 through 308   24.2473   26.5010   32.4189   34.7875   28.9162   35.5226   30.2009   22.0000   26.4000   33.1000   36.1000   28.4000   33.4000   28.2000  Columns 309 through 315   24.1533   19.4709   18.2852   22.0597   19.2040   20.6719   22.5350   22.8000   20.3000   16.1000   22.1000   19.4000   21.6000   23.8000  Columns 316 through 322   17.3670   19.0604   19.3382   22.5443   21.3041   23.1810   22.7061   16.2000   17.8000   19.8000   23.1000   21.0000   23.8000   23.1000  Columns 323 through 329   20.5965   18.3056   23.5467   24.9056   22.9716   21.5595   21.3041   20.4000   18.5000   25.0000   24.6000   23.0000   22.2000   19.3000  Columns 330 through 336   25.0149   21.6011   16.6778   20.7220   23.1595   23.1583   21.2709   22.6000   19.8000   17.1000   19.4000   22.2000   20.7000   21.1000  Columns 337 through 343   20.5881   20.0957   22.1791   21.6646   20.9052   32.2760   19.6094   19.5000   18.5000   20.6000   19.0000   18.7000   32.7000   16.5000  Columns 344 through 350   26.6120   30.8497   18.2102   17.3026   24.0279   27.7069   28.6764   23.9000   31.2000   17.5000   17.2000   23.1000   24.5000   26.6000  Columns 351 through 357   24.0160   22.8876   19.0665   27.5481   18.8396   20.1889   17.1304   22.9000   24.1000   18.6000   30.1000   18.2000   20.6000   17.8000  Columns 358 through 364   19.3401   22.0580   20.7871   25.3794   19.9338   23.0456   20.1196   21.7000   22.7000   22.6000   25.0000   19.9000   20.8000   16.8000  Columns 365 through 371   23.6761   32.1277   24.0001   21.9790   51.1021   48.6596   51.0467   21.9000   27.5000   21.9000   23.1000   50.0000   50.0000   50.0000  Columns 372 through 378   38.7150   40.0930   11.7337   11.7271   19.3180   12.2218   14.0871   50.0000   50.0000   13.8000   13.8000   15.0000   13.9000   13.3000  Columns 379 through 385   10.6245   12.3102   11.2811   12.5886   12.6262   12.7699    8.7457   13.1000   10.2000   10.4000   10.9000   11.3000   12.3000    8.8000  Columns 386 through 392    8.8422    5.2698    8.0072    8.1700   14.5322   17.5716   16.0186    7.2000   10.5000    7.4000   10.2000   11.5000   15.1000   23.2000  Columns 393 through 399    9.8385   19.5303   15.8293   16.7939   16.1594   16.0031    5.2560    9.7000   13.8000   12.7000   13.1000   12.5000    8.5000    5.0000  Columns 400 through 406   11.0778    7.5946   12.6534   13.7895    7.5276    6.5614    4.2802    6.3000    5.6000    7.2000   12.1000    8.3000    8.5000    5.0000  Columns 407 through 413   13.7780   28.4038   16.2167   15.3346   16.2930   10.6613   11.2681   11.9000   27.9000   17.2000   27.5000   15.0000   17.2000   17.9000  Columns 414 through 420   15.1122    7.6163    7.5657    8.3258   10.5912    8.7514   10.9284   16.3000    7.0000    7.2000    7.5000   10.4000    8.8000    8.4000  Columns 421 through 427   16.8908   18.9752   21.6162    9.5188   12.4425    8.3453   14.5831   16.7000   14.2000   20.8000   13.4000   11.7000    8.3000   10.2000  Columns 428 through 434    9.2716   13.8301    9.5708   14.5073   11.7783   19.1158   16.5270   10.9000   11.0000    9.5000   14.5000   14.1000   16.1000   14.3000  Columns 435 through 441   14.5899    9.5630   11.7702    7.7339    5.5916   11.7561    6.6963   11.7000   13.4000    9.6000    8.7000    8.4000   12.8000   10.5000  Columns 442 through 448   12.4933   17.3840   12.9751   10.0512    9.2991   15.4655   14.4212   17.1000   18.4000   15.4000   10.8000   11.8000   14.9000   12.6000  Columns 449 through 455   13.2374   13.2950   11.7887   14.2879   15.7591   12.5250   10.9566   14.1000   13.0000   13.4000   15.2000   16.1000   17.8000   14.9000  Columns 456 through 462   13.5464   11.8807   12.4477   16.1538   16.4501   16.3458   18.2755   14.1000   12.7000   13.5000   14.9000   20.0000   16.4000   17.7000  Columns 463 through 469   17.0225   20.7452   18.1601   20.7623   12.4873   15.6683   15.4485   19.5000   20.2000   21.4000   19.9000   19.0000   19.1000   19.1000  Columns 470 through 476   19.0019   17.4639   22.5748   20.2223   22.6186   17.8242   13.9765   20.1000   19.9000   19.6000   23.2000   29.8000   13.8000   13.3000  Columns 477 through 483   16.1047   11.9184   16.2553   22.4462   23.2027   26.7181   26.4324   16.7000   12.0000   14.6000   21.4000   23.0000   23.7000   25.0000  Columns 484 through 490   21.5557   20.0931   20.0937   16.1954   23.1288   15.7670   12.6886   21.8000   20.6000   21.2000   19.1000   20.6000   15.2000    7.0000  Columns 491 through 497    8.1229   18.0084   20.7898   20.3537   22.0706   21.7872   19.0696    8.1000   13.6000   20.1000   21.8000   24.5000   23.1000   19.7000  Columns 498 through 504   19.4128   21.0991   18.7917   20.1158   22.0507   17.6495   24.3503   18.3000   21.2000   17.5000   16.8000   22.4000   20.6000   23.9000  Columns 505 through 506   22.1611   16.1823   22.0000   11.9000

您可以看到,大多数样本的匹配度较高,并且相对接近。然而,一些输出相差甚远……所以现在关键在于调整神经网络,但不要调整过度,否则会导致数据过拟合。

有关sim的更多详细信息,请查看文档: http://www.mathworks.com/help/nnet/ref/sim.html

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