1、KNN算法概述
kNN算法的核心思想是如果一个样本在特征空间中的k个最相邻的样本中的大多数属于某一个类别，则该样本也属于这个类别，并具有这个类别上样本的特性。该方法在确定分类决策上只依据最邻近的一个或者几个样本的类别来决定待分样本所属的类别。
2、KNN算法介绍
最简单最初级的分类器是将全部的训练数据所对应的类别都记录下来，当测试对象的属性和某个训练对象的属性完全匹配时，便可以对其进行分类。但是怎么可能所有测试对象都会找到与之完全匹配的训练对象呢，其次就是存在一个测试对象同时与多个训练对象匹配，导致一个训练对象被分到了多个类的问题，基于这些问题呢，就产生了KNN。
KNN是通过测量不同特征值之间的距离进行分类。它的的思路是：如果一个样本在特征空间中的k个最相似(即特征空间中最邻近)的样本中的大多数属于某一个类别，则该样本也属于这个类别。K通常是不大于20的整数。KNN算法中，所选择的邻居都是已经正确分类的对象。该方法在定类决策上只依据最邻近的一个或者几个样本的类别来决定待分样本所属的类别。
下面通过一个简单的例子说明一下：如下图，绿色圆要被决定赋予哪个类，是红色三角形还是蓝色四方形？如果K=3，由于红色三角形所占比例为2/3，绿色圆将被赋予红色三角形那个类，如果K=5，由于蓝色四方形比例为3/5，因此绿色圆被赋予蓝色四方形类。
由此也说明了KNN算法的结果很大程度取决于K的选择。
在KNN中，通过计算对象间距离来作为各个对象之间的非相似性指标，避免了对象之间的匹配问题，在这里距离一般使用欧氏距离或曼哈顿距离：
同时，KNN通过依据k个对象中占优的类别进行决策，而不是单一的对象类别决策。这两点就是KNN算法的优势。
接下来对KNN算法的思想总结一下：就是在训练集中数据和标签已知的情况下，输入测试数据，将测试数据的特征与训练集中对应的特征进行相互比较，找到训练集中与之最为相似的前K个数据，则该测试数据对应的类别就是K个数据中出现次数最多的那个分类，其算法的描述为：
1）计算测试数据与各个训练数据之间的距离；
2）按照距离的递增关系进行排序；
3）选取距离最小的K个点；
4）确定前K个点所在类别的出现频率；
5）返回前K个点中出现频率最高的类别作为测试数据的预测分类。
3、算法实现
KNN算法不仅可以用于分类，还可以用于回归。通过找出一个样本的k个最近邻居，将这些邻居的属性的平均值赋给该样本，就可以得到该样本的属性。更有用的方法是将不同距离的邻居对该样本产生的影响给予不同的权值(weight)，如权值与距离成反比。
训练数据：
40920 8.326976 0.953952 3 14488 7.153469 1.673904 2 26052 1.441871 0.805124 1 75136 13.147394 0.428964 1 38344 1.669788 0.134296 1 72993 10.141740 1.032955 1 35948 6.830792 1.213192 3 42666 13.276369 0.543880 3 67497 8.631577 0.749278 1 35483 12.273169 1.508053 3 50242 3.723498 0.831917 1 63275 8.385879 1.669485 1 5569 4.875435 0.728658 2 51052 4.680098 0.625224 1 77372 15.299570 0.331351 1 43673 1.889461 0.191283 1 61364 7.516754 1.269164 1 69673 14.239195 0.261333 1 15669 0.000000 1.250185 2 28488 10.528555 1.304844 3 6487 3.540265 0.822483 2 37708 2.991551 0.833920 1 22620 5.297865 0.638306 2 28782 6.593803 0.187108 3 19739 2.816760 1.686209 2 36788 12.458258 0.649617 3 5741 0.000000 1.656418 2 28567 9.968648 0.731232 3 6808 1.364838 0.640103 2 41611 0.230453 1.151996 1 36661 11.865402 0.882810 3 43605 0.120460 1.352013 1 15360 8.545204 1.340429 3 63796 5.856649 0.160006 1 10743 9.665618 0.778626 2 70808 9.778763 1.084103 1 72011 4.932976 0.632026 1 5914 2.216246 0.587095 2 14851 14.305636 0.632317 3 33553 12.591889 0.686581 3 44952 3.424649 1.004504 1 17934 0.000000 0.147573 2 27738 8.533823 0.205324 3 29290 9.829528 0.238620 3 42330 11.492186 0.263499 3 36429 3.570968 0.832254 1 39623 1.771228 0.207612 1 32404 3.513921 0.991854 1 27268 4.398172 0.975024 1 5477 4.276823 1.174874 2 14254 5.946014 1.614244 2 68613 13.798970 0.724375 1 41539 10.393591 1.663724 3 7917 3.007577 0.297302 2 21331 1.031938 0.486174 2 8338 4.751212 0.064693 2 5176 3.692269 1.655113 2 18983 10.448091 0.267652 3 68837 10.585786 0.329557 1 13438 1.604501 0.069064 2 48849 3.679497 0.961466 1 12285 3.795146 0.696694 2 7826 2.531885 1.659173 2 5565 9.733340 0.977746 2 10346 6.093067 1.413798 2 1823 7.712960 1.054927 2 9744 11.470364 0.760461 3 16857 2.886529 0.934416 2 39336 10.054373 1.138351 3 65230 9.972470 0.881876 1 2463 2.335785 1.366145 2 27353 11.375155 1.528626 3 16191 0.000000 0.605619 2 12258 4.126787 0.357501 2 42377 6.319522 1.058602 1 25607 8.680527 0.086955 3 77450 14.856391 1.129823 1 58732 2.454285 0.222380 1 46426 7.292202 0.548607 3 32688 8.745137 0.857348 3 64890 8.579001 0.683048 1 8554 2.507302 0.869177 2 28861 11.415476 1.505466 3 42050 4.838540 1.680892 1 32193 10.339507 0.583646 3 64895 6.573742 1.151433 1 2355 6.539397 0.462065 2 0 2.209159 0.723567 2 70406 11.196378 0.836326 1 57399 4.229595 0.128253 1 41732 9.505944 0.005273 3 11429 8.652725 1.348934 3 75270 17.101108 0.490712 1 5459 7.871839 0.717662 2 73520 8.262131 1.361646 1 40279 9.015635 1.658555 3 21540 9.215351 0.806762 3 17694 6.375007 0.033678 2 22329 2.262014 1.022169 1 46570 5.677110 0.709469 1 42403 11.293017 0.207976 3 33654 6.590043 1.353117 1 9171 4.711960 0.194167 2 28122 8.768099 1.108041 3 34095 11.502519 0.545097 3 1774 4.682812 0.578112 2 40131 12.446578 0.300754 3 13994 12.908384 1.657722 3 77064 12.601108 0.974527 1 11210 3.929456 0.025466 2 6122 9.751503 1.182050 3 15341 3.043767 0.888168 2 44373 4.391522 0.807100 1 28454 11.695276 0.679015 3 63771 7.879742 0.154263 1 9217 5.613163 0.933632 2 69076 9.140172 0.851300 1 24489 4.258644 0.206892 1 16871 6.799831 1.221171 2 39776 8.752758 0.484418 3 5901 1.123033 1.180352 2 40987 10.833248 1.585426 3 7479 3.051618 0.026781 2 38768 5.308409 0.030683 3 4933 1.841792 0.028099 2 32311 2.261978 1.605603 1 26501 11.573696 1.061347 3 37433 8.038764 1.083910 3 23503 10.734007 0.103715 3 68607 9.661909 0.350772 1 27742 9.005850 0.548737 3 11303 0.000000 0.539131 2 0 5.757140 1.062373 2 32729 9.164656 1.624565 3 24619 1.318340 1.436243 1 42414 14.075597 0.695934 3 20210 10.107550 1.308398 3 33225 7.960293 1.219760 3 54483 6.317292 0.018209 1 18475 12.664194 0.595653 3 33926 2.906644 0.581657 1 43865 2.388241 0.913938 1 26547 6.024471 0.486215 3 44404 7.226764 1.255329 3 16674 4.183997 1.275290 2 8123 11.850211 1.096981 3 42747 11.661797 1.167935 3 56054 3.574967 0.494666 1 10933 0.000000 0.107475 2 18121 7.937657 0.904799 3 11272 3.365027 1.014085 2 16297 0.000000 0.367491 2 28168 13.860672 1.293270 3 40963 10.306714 1.211594 3 31685 7.228002 0.670670 3 55164 4.508740 1.036192 1 17595 0.366328 0.163652 2 1862 3.299444 0.575152 2 57087 0.573287 0.607915 1 63082 9.183738 0.012280 1 51213 7.842646 1.060636 3 6487 4.750964 0.558240 2 4805 11.438702 1.556334 3 30302 8.243063 1.122768 3 68680 7.949017 0.271865 1 17591 7.875477 0.227085 2 74391 9.569087 0.364856 1 37217 7.750103 0.869094 3 42814 0.000000 1.515293 1 14738 3.396030 0.633977 2 19896 11.916091 0.025294 3 14673 0.460758 0.689586 2 32011 13.087566 0.476002 3 58736 4.589016 1.672600 1 54744 8.397217 1.534103 1 29482 5.562772 1.689388 1 27698 10.905159 0.619091 3 11443 1.311441 1.169887 2 56117 10.647170 0.980141 3 39514 0.000000 0.481918 1 26627 8.503025 0.830861 3 16525 0.436880 1.395314 2 24368 6.127867 1.102179 1 22160 12.112492 0.359680 3 6030 1.264968 1.141582 2 6468 6.067568 1.327047 2 22945 8.010964 1.681648 3 18520 3.791084 0.304072 2 34914 11.773195 1.262621 3 6121 8.339588 1.443357 2 38063 2.563092 1.464013 1 23410 5.954216 0.953782 1 35073 9.288374 0.767318 3 52914 3.976796 1.043109 1 16801 8.585227 1.455708 3 9533 1.271946 0.796506 2 16721 0.000000 0.242778 2 5832 0.000000 0.089749 2 44591 11.521298 0.300860 3 10143 1.139447 0.415373 2 21609 5.699090 1.391892 2 23817 2.449378 1.322560 1 15640 0.000000 1.228380 2 8847 3.168365 0.053993 2 50939 10.428610 1.126257 3 28521 2.943070 1.446816 1 32901 10.441348 0.975283 3 42850 12.478764 1.628726 3 13499 5.856902 0.363883 2 40345 2.476420 0.096075 1 43547 1.826637 0.811457 1 70758 4.324451 0.328235 1 19780 1.376085 1.178359 2 44484 5.342462 0.394527 1 54462 11.835521 0.693301 3 20085 12.423687 1.424264 3 42291 12.161273 0.071131 3 47550 8.148360 1.649194 3 11938 1.531067 1.549756 2 40699 3.200912 0.309679 1 70908 8.862691 0.530506 1 73989 6.370551 0.369350 1 11872 2.468841 0.145060 2 48463 11.054212 0.141508 3 15987 2.037080 0.715243 2 70036 13.364030 0.549972 1 32967 10.249135 0.192735 3 63249 10.464252 1.669767 1 42795 9.424574 0.013725 3 14459 4.458902 0.268444 2 19973 0.000000 0.575976 2 5494 9.686082 1.029808 3 67902 13.649402 1.052618 1 25621 13.181148 0.273014 3 27545 3.877472 0.401600 1 58656 1.413952 0.451380 1 7327 4.248986 1.430249 2 64555 8.779183 0.845947 1 8998 4.156252 0.097109 2 11752 5.580018 0.158401 2 76319 15.040440 1.366898 1 27665 12.793870 1.307323 3 67417 3.254877 0.669546 1 21808 10.725607 0.588588 3 15326 8.256473 0.765891 2 20057 8.033892 1.618562 3 79341 10.702532 0.204792 1 15636 5.062996 1.132555 2 35602 10.772286 0.668721 3 28544 1.892354 0.837028 1 57663 1.019966 0.372320 1 78727 15.546043 0.729742 1 68255 11.638205 0.409125 1 14964 3.427886 0.975616 2 21835 11.246174 1.475586 3 7487 0.000000 0.645045 2 8700 0.000000 1.424017 2 26226 8.242553 0.279069 3 65899 8.700060 0.101807 1 6543 0.812344 0.260334 2 46556 2.448235 1.176829 1 71038 13.230078 0.616147 1 47657 0.236133 0.340840 1 19600 11.155826 0.335131 3 37422 11.029636 0.505769 3 1363 2.901181 1.646633 2 26535 3.924594 1.143120 1 47707 2.524806 1.292848 1 38055 3.527474 1.449158 1 6286 3.384281 0.889268 2 10747 0.000000 1.107592 2 44883 11.898890 0.406441 3 56823 3.529892 1.375844 1 68086 11.442677 0.696919 1 70242 10.308145 0.422722 1 11409 8.540529 0.727373 2 67671 7.156949 1.691682 1 61238 0.720675 0.847574 1 17774 0.229405 1.038603 2 53376 3.399331 0.077501 1 30930 6.157239 0.580133 1 28987 1.239698 0.719989 1 13655 6.036854 0.016548 2 7227 5.258665 0.933722 2 40409 12.393001 1.571281 3 13605 9.627613 0.935842 2 26400 11.130453 0.597610 3 13491 8.842595 0.349768 3 30232 10.690010 1.456595 3 43253 5.714718 1.674780 3 55536 3.052505 1.335804 1 8807 0.000000 0.059025 2 25783 9.945307 1.287952 3 22812 2.719723 1.142148 1 77826 11.154055 1.608486 1 38172 2.687918 0.660836 1 31676 10.037847 0.962245 3 74038 12.404762 1.112080 1 44738 10.237305 0.633422 3 17410 4.745392 0.662520 2 5688 4.639461 1.569431 2 36642 3.149310 0.639669 1 29956 13.406875 1.639194 3 60350 6.068668 0.881241 1 23758 9.477022 0.899002 3 25780 3.897620 0.560201 2 11342 5.463615 1.203677 2 36109 3.369267 1.575043 1 14292 5.234562 0.825954 2 11160 0.000000 0.722170 2 23762 12.979069 0.504068 3 39567 5.376564 0.557476 1 25647 13.527910 1.586732 3 14814 2.196889 0.784587 2 73590 10.691748 0.007509 1 35187 1.659242 0.447066 1 49459 8.369667 0.656697 3 31657 13.157197 0.143248 3 6259 8.199667 0.908508 2 33101 4.441669 0.439381 3 27107 9.846492 0.644523 3 17824 0.019540 0.977949 2 43536 8.253774 0.748700 3 67705 6.038620 1.509646 1 35283 6.091587 1.694641 3 71308 8.986820 1.225165 1 31054 11.508473 1.624296 3 52387 8.807734 0.713922 3 40328 0.000000 0.816676 1 34844 8.889202 1.665414 3 11607 3.178117 0.542752 2 64306 7.013795 0.139909 1 32721 9.605014 0.065254 3 33170 1.230540 1.331674 1 37192 10.412811 0.890803 3 13089 0.000000 0.567161 2 66491 9.699991 0.122011 1 15941 0.000000 0.061191 2 4272 4.455293 0.272135 2 48812 3.020977 1.502803 1 28818 8.099278 0.216317 3 35394 1.157764 1.603217 1 71791 10.105396 0.121067 1 40668 11.230148 0.408603 3 39580 9.070058 0.011379 3 11786 0.566460 0.478837 2 19251 0.000000 0.487300 2 56594 8.956369 1.193484 3 54495 1.523057 0.620528 1 11844 2.749006 0.169855 2 45465 9.235393 0.188350 3 31033 10.555573 0.403927 3 16633 6.956372 1.519308 2 13887 0.636281 1.273984 2 52603 3.574737 0.075163 1 72000 9.032486 1.461809 1 68497 5.958993 0.023012 1 35135 2.435300 1.211744 1 26397 10.539731 1.638248 3 7313 7.646702 0.056513 2 91273 20.919349 0.644571 1 24743 1.424726 0.838447 1 31690 6.748663 0.890223 3 15432 2.289167 0.114881 2 58394 5.548377 0.402238 1 33962 6.057227 0.432666 1 31442 10.828595 0.559955 3 31044 11.318160 0.271094 3 29938 13.265311 0.633903 3 9875 0.000000 1.496715 2 51542 6.517133 0.402519 3 11878 4.934374 1.520028 2 69241 10.151738 0.896433 1 37776 2.425781 1.559467 1 68997 9.778962 1.195498 1 67416 12.219950 0.657677 1 59225 7.394151 0.954434 1 29138 8.518535 0.742546 3 5962 2.798700 0.662632 2 10847 0.637930 0.617373 2 70527 10.750490 0.097415 1 9610 0.625382 0.140969 2 64734 10.027968 0.282787 1 25941 9.817347 0.364197 3 2763 0.646828 1.266069 2 55601 3.347111 0.914294 1 31128 11.816892 0.193798 3 5181 0.000000 1.480198 2 69982 10.945666 0.993219 1 52440 10.244706 0.280539 3 57350 2.579801 1.149172 1 57869 2.630410 0.098869 1 56557 11.746200 1.695517 3 42342 8.104232 1.326277 3 15560 12.409743 0.790295 3 34826 12.167844 1.328086 3 8569 3.198408 0.299287 2 77623 16.055513 0.541052 1 78184 7.138659 0.158481 1 7036 4.831041 0.761419 2 69616 10.082890 1.373611 1 21546 10.066867 0.788470 3 36715 8.129538 0.329913 3 20522 3.012463 1.138108 2 42349 3.720391 0.845974 1 9037 0.773493 1.148256 2 26728 10.962941 1.037324 3 587 0.177621 0.162614 2 48915 3.085853 0.967899 1 9824 8.426781 0.202558 2 4135 1.825927 1.128347 2 9666 2.185155 1.010173 2 59333 7.184595 1.261338 1 36198 0.000000 0.116525 1 34909 8.901752 1.033527 3 47516 2.451497 1.358795 1 55807 3.213631 0.432044 1 14036 3.974739 0.723929 2 42856 9.601306 0.619232 3 64007 8.363897 0.445341 1 59428 6.381484 1.365019 1 13730 0.000000 1.403914 2 41740 9.609836 1.438105 3 63546 9.904741 0.985862 1 30417 7.185807 1.489102 3 69636 5.466703 1.216571 1 64660 0.000000 0.915898 1 14883 4.575443 0.535671 2 7965 3.277076 1.010868 2 68620 10.246623 1.239634 1 8738 2.341735 1.060235 2 7544 3.201046 0.498843 2 6377 6.066013 0.120927 2 36842 8.829379 0.895657 3 81046 15.833048 1.568245 1 67736 13.516711 1.220153 1 32492 0.664284 1.116755 1 39299 6.325139 0.605109 3 77289 8.677499 0.344373 1 33835 8.188005 0.964896 3 71890 9.414263 0.384030 1 32054 9.196547 1.138253 3 38579 10.202968 0.452363 3 55984 2.119439 1.481661 1 72694 13.635078 0.858314 1 42299 0.083443 0.701669 1 26635 9.149096 1.051446 3 8579 1.933803 1.374388 2 37302 14.115544 0.676198 3 22878 8.933736 0.943352 3 4364 2.661254 0.946117 2 4985 0.988432 1.305027 2 37068 2.063741 1.125946 1 41137 2.220590 0.690754 1 67759 6.424849 0.806641 1 11831 1.156153 1.613674 2 34502 3.032720 0.601847 1 4088 3.076828 0.952089 2 15199 0.000000 0.318105 2 17309 7.750480 0.554015 3 42816 10.958135 1.482500 3 43751 10.222018 0.488678 3 58335 2.367988 0.435741 1 75039 7.686054 1.381455 1 42878 11.464879 1.481589 3 42770 11.075735 0.089726 3 8848 3.543989 0.345853 2 31340 8.123889 1.282880 3 41413 4.331769 0.754467 3 12731 0.120865 1.211961 2 22447 6.116109 0.701523 3 33564 7.474534 0.505790 3 48907 8.819454 0.649292 3 8762 6.802144 0.615284 2 46696 12.666325 0.931960 3 36851 8.636180 0.399333 3 67639 11.730991 1.289833 1 171 8.132449 0.039062 2 26674 10.296589 1.496144 3 8739 7.583906 1.005764 2 66668 9.777806 0.496377 1 68732 8.833546 0.513876 1 69995 4.907899 1.518036 1 82008 8.362736 1.285939 1 25054 9.084726 1.606312 3 33085 14.164141 0.560970 3 41379 9.080683 0.989920 3 39417 6.522767 0.038548 3 12556 3.690342 0.462281 2 39432 3.563706 0.242019 1 38010 1.065870 1.141569 1 69306 6.683796 1.456317 1 38000 1.712874 0.243945 1 46321 13.109929 1.280111 3 66293 11.327910 0.780977 1 22730 4.545711 1.233254 1 5952 3.367889 0.468104 2 72308 8.326224 0.567347 1 60338 8.978339 1.442034 1 13301 5.655826 1.582159 2 27884 8.855312 0.570684 3 11188 6.649568 0.544233 2 56796 3.966325 0.850410 1 8571 1.924045 1.664782 2 4914 6.004812 0.280369 2 10784 0.000000 0.375849 2 39296 9.923018 0.092192 3 13113 2.389084 0.119284 2 70204 13.663189 0.133251 1 46813 11.434976 0.321216 3 11697 0.358270 1.292858 2 44183 9.598873 0.223524 3 2225 6.375275 0.608040 2 29066 11.580532 0.458401 3 4245 5.319324 1.598070 2 34379 4.324031 1.603481 1 44441 2.358370 1.273204 1 2022 0.000000 1.182708 2 26866 12.824376 0.890411 3 57070 1.587247 1.456982 1 32932 8.510324 1.520683 3 51967 10.428884 1.187734 3 44432 8.346618 0.042318 3 67066 7.541444 0.809226 1 17262 2.540946 1.583286 2 79728 9.473047 0.692513 1 14259 0.352284 0.474080 2 6122 0.000000 0.589826 2 76879 12.405171 0.567201 1 11426 4.126775 0.871452 2 2493 0.034087 0.335848 2 19910 1.177634 0.075106 2 10939 0.000000 0.479996 2 17716 0.994909 0.611135 2 31390 11.053664 1.180117 3 20375 0.000000 1.679729 2 26309 2.495011 1.459589 1 33484 11.516831 0.001156 3 45944 9.213215 0.797743 3 4249 5.332865 0.109288 2 6089 0.000000 1.689771 2 7513 0.000000 1.126053 2 27862 12.640062 1.690903 3 39038 2.693142 1.317518 1 19218 3.328969 0.268271 2 62911 7.193166 1.117456 1 77758 6.615512 1.521012 1 27940 8.000567 0.835341 3 2194 4.017541 0.512104 2 37072 13.245859 0.927465 3 15585 5.970616 0.813624 2 25577 11.668719 0.886902 3 8777 4.283237 1.272728 2 29016 10.742963 0.971401 3 21910 12.326672 1.592608 3 12916 0.000000 0.344622 2 10976 0.000000 0.922846 2 79065 10.602095 0.573686 1 36759 10.861859 1.155054 3 50011 1.229094 1.638690 1 1155 0.410392 1.313401 2 71600 14.552711 0.616162 1 30817 14.178043 0.616313 3 54559 14.136260 0.362388 1 29764 0.093534 1.207194 1 69100 10.929021 0.403110 1 47324 11.432919 0.825959 3 73199 9.134527 0.586846 1 44461 5.071432 1.421420 1 45617 11.460254 1.541749 3 28221 11.620039 1.103553 3 7091 4.022079 0.207307 2 6110 3.057842 1.631262 2 79016 7.782169 0.404385 1 18289 7.981741 0.929789 3 43679 4.601363 0.268326 1 22075 2.595564 1.115375 1 23535 10.049077 0.391045 3 25301 3.265444 1.572970 2 32256 11.780282 1.511014 3 36951 3.075975 0.286284 1 31290 1.795307 0.194343 1 38953 11.106979 0.202415 3 35257 5.994413 0.800021 1 25847 9.706062 1.012182 3 32680 10.582992 0.836025 3 62018 7.038266 1.458979 1 9074 0.023771 0.015314 2 33004 12.823982 0.676371 3 44588 3.617770 0.493483 1 32565 8.346684 0.253317 3 38563 6.104317 0.099207 1 75668 16.207776 0.584973 1 9069 6.401969 1.691873 2 53395 2.298696 0.559757 1 28631 7.661515 0.055981 3 71036 6.353608 1.645301 1 71142 10.442780 0.335870 1 37653 3.834509 1.346121 1 76839 10.998587 0.584555 1 9916 2.695935 1.512111 2 38889 3.356646 0.324230 1 39075 14.677836 0.793183 3 48071 1.551934 0.130902 1 7275 2.464739 0.223502 2 41804 1.533216 1.007481 1 35665 12.473921 0.162910 3 67956 6.491596 0.032576 1 41892 10.506276 1.510747 3 38844 4.380388 0.748506 1 74197 13.670988 1.687944 1 14201 8.317599 0.390409 2 3908 0.000000 0.556245 2 2459 0.000000 0.290218 2 32027 10.095799 1.188148 3 12870 0.860695 1.482632 2 9880 1.557564 0.711278 2 72784 10.072779 0.756030 1 17521 0.000000 0.431468 2 50283 7.140817 0.883813 3 33536 11.384548 1.438307 3 9452 3.214568 1.083536 2 37457 11.720655 0.301636 3 17724 6.374475 1.475925 3 43869 5.749684 0.198875 3 264 3.871808 0.552602 2 25736 8.336309 0.636238 3 39584 9.710442 1.503735 3 31246 1.532611 1.433898 1 49567 9.785785 0.984614 3 7052 2.633627 1.097866 2 35493 9.238935 0.494701 3 10986 1.205656 1.398803 2 49508 3.124909 1.670121 1 5734 7.935489 1.585044 2 65479 12.746636 1.560352 1 77268 10.732563 0.545321 1 28490 3.977403 0.766103 1 13546 4.194426 0.450663 2 37166 9.610286 0.142912 3 16381 4.797555 1.260455 2 10848 1.615279 0.093002 2 35405 4.614771 1.027105 1 15917 0.000000 1.369726 2 6131 0.608457 0.512220 2 67432 6.558239 0.667579 1 30354 12.315116 0.197068 3 69696 7.014973 1.494616 1 33481 8.822304 1.194177 3 43075 10.086796 0.570455 3 38343 7.241614 1.661627 3 14318 4.602395 1.511768 2 5367 7.434921 0.079792 2 37894 10.467570 1.595418 3 36172 9.948127 0.003663 3 40123 2.478529 1.568987 1 10976 5.938545 0.878540 2 12705 0.000000 0.948004 2 12495 5.559181 1.357926 2 35681 9.776654 0.535966 3 46202 3.092056 0.490906 1 11505 0.000000 1.623311 2 22834 4.459495 0.538867 1 49901 8.334306 1.646600 3 71932 11.226654 0.384686 1 13279 3.904737 1.597294 2 49112 7.038205 1.211329 3 77129 9.836120 1.054340 1 37447 1.990976 0.378081 1 62397 9.005302 0.485385 1 0 1.772510 1.039873 2 15476 0.458674 0.819560 2 40625 10.003919 0.231658 3 36706 0.520807 1.476008 1 28580 10.678214 1.431837 3 25862 4.425992 1.363842 1 63488 12.035355 0.831222 1 33944 10.606732 1.253858 3 30099 1.568653 0.684264 1 13725 2.545434 0.024271 2 36768 10.264062 0.982593 3 64656 9.866276 0.685218 1 14927 0.142704 0.057455 2 43231 9.853270 1.521432 3 66087 6.596604 1.653574 1 19806 2.602287 1.321481 2 41081 10.411776 0.664168 3 10277 7.083449 0.622589 2 7014 2.080068 1.254441 2 17275 0.522844 1.622458 2 31600 10.362000 1.544827 3
python版：
#!/usr/bin/python import sys import copy import getopt def usage(): print '''Help Information: -h, --help: show help information; -r, --train: train file; -t, --test: test file; -k, --kst: k number; ''' def getclass(nest_label): lendic = {} for i in range(0,len(nest_label),1): if lendic.has_key(nest_label[i]): lendic[nest_label[i]] += 1 else: lendic[nest_label[i]] = 1 vec = sorted(lendic.iteritems(),key=lambda asd:asd[1],reverse=True) maxlen = vec[0][1] maxidx = {} for i in range(0,len(vec),1): if vec[i][1]<maxlen: break idx = 0 for k in range(0,len(nest_label),1): if nest_label[k]==vec[i][0]: idx = k break maxidx[vec[i][0]] = idx vecmax = sorted(maxidx.iteritems(),key=lambda asd:asd[1],reverse=False) return vecmax[0][0] def classify(testdata,orgdata,maxdata,mindata,label,kst): for i in range(0,len(testdata),1): if testdata[i] > maxdata[i]: testdata[i] = 1.0 elif testdata[i] < mindata[i]: testdata[i] = 0.0 elif maxdata[i]!=mindata[i]: testdata[i] = float(testdata[i] - mindata[i]) / (maxdata[i] - mindata[i]) dist_dic = {} for i in range(0,len(orgdata),1): dist = 0 for k in range(0,len(orgdata[i]),1): dist += (orgdata[i][k] - testdata[k])**2 dist = dist**0.5 dist_dic[i] = dist dist_ls = sorted(dist_dic.iteritems(),key=lambda asd:asd[1],reverse=False) nest_label = [] if kst>len(dist_ls): kst = len(dist_ls) for i in range(0,kst,1): index = dist_ls[i][0] nest_label.append(label[index]) return getclass(nest_label) def autoNorm(orgdata): mindata = copy.deepcopy(orgdata[0]) maxdata = copy.deepcopy(orgdata[0]) for i in range(1,len(orgdata),1): for k in range(0,len(mindata),1): if orgdata[i][k] > maxdata[k]: maxdata[k] = orgdata[i][k] if orgdata[i][k] < mindata[k]: mindata[k] = orgdata[i][k] for i in range(0,len(orgdata),1): for k in range(0,len(orgdata[i]),1): if maxdata[k]!=mindata[k]: orgdata[i][k] = float(orgdata[i][k] - mindata[k]) / (maxdata[k] - mindata[k]) return mindata,maxdata if __name__=="__main__": #set parameter try: opts, args = getopt.getopt(sys.argv[1:], "hr:t:k:", ["help", "train=","test=","kst="]) except getopt.GetoptError, err: print str(err) usage() sys.exit(1) sys.stderr.write("\ntrain.py : a python script for perception training.\n") sys.stderr.write("Copyright 2016 sxron, search, Sogou. \n") sys.stderr.write("Email: shixiang08abc@gmail.com \n\n") train = '' test = '' kst = 10 for i, f in opts: if i in ("-h", "--help"): usage() sys.exit(1) elif i in ("-r", "--train"): train = f elif i in ("-t", "--test"): test = f elif i in ("-k", "--kst"): kst = int(f) else: assert False, "unknown option" print "start trian parameter \ttrain:%s\ttest:%s\tkst:%d" % (train,test,kst) #read train file orgdata = [] label = [] fin = open(train,'r') while 1: line = fin.readline() if not line: break ts = line.strip().split('\t') if len(ts)==4: try: lb1 = float(ts[0].strip()) lb2 = float(ts[1].strip()) lb3 = float(ts[2].strip()) lb = int(ts[3].strip()) except: continue data = [] data.append(lb1) data.append(lb2) data.append(lb3) orgdata.append(data) label.append(lb) fin.close() #read test file testdata = [] rlabel = [] fin = open(test,'r') while 1: line = fin.readline() if not line: break ts = line.strip().split('\t') if len(ts)==4: try: lb1 = float(ts[0].strip()) lb2 = float(ts[1].strip()) lb3 = float(ts[2].strip()) lb = int(ts[3].strip()) except: continue data = [] data.append(lb1) data.append(lb2) data.append(lb3) testdata.append(data) rlabel.append(lb) fin.close() mindata,maxdata = autoNorm(orgdata) errnum = 0 for i in range(0,len(testdata),1): result_label = classify(testdata[i],orgdata,maxdata,mindata,label,kst) if result_label!=rlabel[i]: print "index:%d\tresult_label:%d\trlabel:%d" % (i,result_label,rlabel[i]) errnum += 1 print "errnum:%d\terrratio:%f" % (errnum,float(errnum)/len(testdata))
PS:这些数据的背后意义：某个妹纸想要找一个男朋友，她收集了婚恋网上面对她感兴趣男士的一些数据，第一个是一年的飞行里程，第二个是每年玩游戏的时间(10小时为单位），第三个是每年吃的冰淇淋量。第四个是结果：3表示很感兴趣，2表示感兴趣，1表示没兴趣。
