php - PHP calculate trend line like excel TREND function

Question

My math is very week and now still figuring how to achieve this with PHP. I was using excel TREND() function. Let's say I have 2 lists of known values

| known_x_values | known_y_values | |----------------|----------------| | 323 | 0.038 | | 373 | 0.046 | | 423 | 0.053 | | 473 | 0.062 | | 523 | 0.071 | | 573 | 0.080 |

And now I need to know the value y when the x = 428. By using excel TREND() function, I get 0.055 as the value y.

Anyone can show me how PHP handle this kind of math questions?
Any help would be appreciated. Thank you.

Answer 1

ExcelTREND()使用最小二乘法。

数学很难，所以我会使用图书馆来完成繁重的工作。在这种情况下php-ai/php-ml。

例子：

use Phpml\Regression\LeastSquares;

$x = [[323], [373], [423], [473], [523], [573]];
$y = [.038, .046, .053, .062, .071, .080];

$regression = new LeastSquares();
$regression->train($x, $y);
echo $regression->predict([428]);

输出：

0.054973333333333235

根据您的精度设置，输出可能会略有不同。

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你当然可以round()或number_format()你希望的结果，例如：

echo number_format($regression->predict([428]), 3);

给出：

0.055