我正在尝试将这个算法从C语言翻译成PHP（用于学习）。这是一个感知器的例子。我复制了用C语言编写的例子，并试图将其翻译成PHP。目前我写了这段代码，我哪里做错了？作为输出，我只知道101次迭代，结果总是1。
这是C语言程序：
#include <stdio.h>#include <stdlib.h>#include <math.h>#include <time.h>#define LEARNING_RATE 0.1#define MAX_ITERATION 100float randomFloat(){ return (float)rand() / (float)RAND_MAX;}int calculateOutput(float weights[], float x, float y){ float sum = x * weights[0] + y * weights[1] + weights[2]; return (sum >= 0) ? 1 : -1;}int main(int argc, char *argv[]){ srand(time(NULL)); float x[208], y[208], weights[3], localError, globalError; int outputs[208], patternCount, i, p, iteration, output; FILE *fp; if ((fp = fopen("test1.txt", "r")) == NULL) { printf("Cannot open file.\n"); exit(1); } i = 0; while (fscanf(fp, "%f %f %d", &x[i], &y[i], &outputs[i]) != EOF) { if (outputs[i] == 0) { outputs[i] = -1; } i++; } patternCount = i; weights[0] = randomFloat(); weights[1] = randomFloat(); weights[2] = randomFloat(); iteration = 0; do { iteration++; globalError = 0; for (p = 0; p < patternCount; p++) { output = calculateOutput(weights, x[p], y[p]); localError = outputs[p] - output; weights[0] += LEARNING_RATE * localError * x[p]; weights[1] += LEARNING_RATE * localError * y[p]; weights[2] += LEARNING_RATE * localError; globalError += (localError*localError); } /* Root Mean Squared Error */ printf("Iteration %d : RMSE = %.4f\n", iteration, sqrt(globalError/patternCount)); } while (globalError != 0 && iteration<=MAX_ITERATION); printf("\nDecision boundary (line) equation: %.2f*x + %.2f*y + %.2f = 0\n", weights[0], weights[1], weights[2]); return 0;}这是我写的代码
<?php define("LEARNING_RATE", 0.1); define("MAX_ITERATION", 100); function randomFloat(){ return (float) mt_rand() / mt_getrandmax(); } function calculateOutput($weights, $x, $y){ $sum = (float) $x * $weights[0] + $y * $weights[1] + $weights[2]; return ($sum >= 0) ? 1 : -1; } srand(time()); $i = 0; $ars = explode("\n",file_get_contents('https://raw.githubusercontent.com/RichardKnop/ansi-c-perceptron/master/test1.txt')); foreach($ars as $ar){ $temp = explode("\t", $ar); $x[$i] = (float) $temp[0]; $y[$i] = (float) $temp[1]; $output[$i] = (int) $temp[2]; if($output[$i] == 0) $output[$i] = -1; $i++; } $patternCount = $i; $weights[0] = randomFloat(); $weights[1] = randomFloat(); $weights[2] = randomFloat(); $iteration = 0; do{ $iteration++; $globalError = 0; for ($p = 0; $p < $patternCount; $p++) { $output = calculateOutput($weights, $x[$p], $y[$p]); $localError = $outputs[$p] - $output; $weights[0] += LEARNING_RATE * $localError * $x[$p]; $weights[1] += LEARNING_RATE * $localError * $y[$p]; $weights[2] += LEARNING_RATE * $localError; $globalError += ($localError*$localError); } $r .= "Iteration $iteration : RMSE = " . sqrt($globalError/$patternCount)."<br>";}while($globalError != 0 && $iteration<=MAX_ITERATION);echo $r;echo "<br><hr><br>";echo "Decision boundary (line) equation: ".$weights[0]."*x + ".$weights[1]."*y + ".$weights[2]." = 0<br>";这两段代码几乎相同，但为什么它不起作用呢？
回答：
$ars = explode("\n",file_get_contents('…'));由于文件以\n结尾，这会导致最后一个数组值为空字符串，从而扰乱foreach($ars as $ar)循环。要将文件读入数组，可以简单地使用：
$ars = file('…');在foreach($ars as $ar)循环中，你使用了错误的名称$output[$i]，而不是$outputs[$i]。
$r .= "Iteration $iteration : RMSE = " . sqrt($globalError/$patternCount)."<br>";}while($globalError != 0 && $iteration<=MAX_ITERATION);echo $r;你没有初始化$r。代替上述代码，你可以使用：
echo "Iteration $iteration : RMSE = " . sqrt($globalError/$patternCount)."<br>"; } while ($globalError != 0 && $iteration<=MAX_ITERATION);