function?result?=?knn（trainX?testY?zuobiaoZ?k）


%?Classify?using?the?Nearest?neighbor?algorithm
%?Inputs:
%?	trainX	???????-?Train?sample?matrix?n*d?n?points?each?d?dimentions
%???testY??????????-?Test?sample?matrix??N*d??測試樣本矩陣
%	k		???????-?Number?of?nearest?neighbors?
%?Outputs:
%	result	???????-?定位點坐標

%??判斷trainX和testY的樣本點維數是否相同???
trainX?=[34?35?38?40?45?60?62?67;36?34?40?36?42?67?40?65;62?40?48?36?47?67?34?62;38?36?40?45?52?65?70?65;?67?42?50?35?36?70?37?64]
testY?=?[38?36?39?41?46?61?64?67;70?38?40?55?50?60?55?40;76?33?56?78?40?52?62?35;76?35?23?61?76?35?57?62;87?62?34?47?36?82?21?63];
zuobiaoZ?=?[0.0?3.0;1.5?3.0;?3.0?3.0;0.0?1.5;3.01.5];
k?=3;
zhunqueZ?=?[0.3?3.0;1.8?1.8;2.0?1.7;0.8?2.9;3.0?2.2]??????????????????????????????%??待定位點的準確坐標
if?size（trainX2）?~=?size（testY2）??????????????????????????????????????
????error?（‘trainX?and?testZ?must?have?same?column?dimensions?!‘）?????????%??維數d應該相同?在同一個點搜集到的WiFi熱點個數相同
end???

%??判斷k近鄰是否可取
n?=?size（trainX1）;???????????????????????????????????????????????????????%??測試樣本點個數???參考點的個數必須大于k的個數
if?（?n????error（‘You?specified?more?neighbors?than?existed?points.‘）
end???????????????????????????????????????????????????????????????????????%??選擇的近鄰數不大于樣本點數

???????????????????????????????
N???????????????????=?size（testY?1）;?????????????????????????????????????%??testZ的行數，即測試集的樣本點數
??????????????????????????????????????????????????????????????????????????%???初始化result矩陣N*1列向量標出testZ的類別


%??按照所選的度量距離，對testY的N個點逐個進行k近鄰分類?

????????????????????????????????????????????????????????
????for?i?=?1:N?
????????dist????????????=?sum（（trainX?-?ones（n1）*testY（i:））.^22）;??????%??dist?表示第i個測試點分別與n個訓練樣本點之間的歐式距離的平方?按行進行求和?dist是個矩陣
????????[m?indices]????=?sort（dist）;?????????????????????????????????????%??按列進行升序排列???
????????histclass???????=?zuobiaoZ（[indices（1:k）]:?）;????????????????????%??取前k個最短距離對應的點所屬的類別，求出k個臨近點的坐標
????????gd??????????????=?sum（histclass）;?????????????????????????????????%??k個臨近點的坐標相加?
????????result（i:）?????=gd/k;????????????????????????????????????????????%??求得定位點的坐標
????????x（i）????????????=result（i1）;
????????y（i）????????????=result（i2）;
????????x1（i）???????????=zhunqueZ（i1）;
????????y1（i）???????????=zhunqueZ（i2）;
????????
????end
???plot（xy‘square‘‘MarkerSize‘7）;
???hold?on;
???plot（x1y1‘*‘‘MarkerSize‘7）;
???????axis（[0?3?0?3]）;
set（gca‘xtick‘[0:0.2:3]‘ytick‘[0:0.2:3]）
????
????

end

?屬性????????????大小?????日期????時間???名稱
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?????文件???????2735??2014-04-17?13:54??knn1.m

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?????????????????2735????????????????????1