我试图理解一个包含以下内容的Udacity线性回归示例：
data = np.loadtxt('data.csv',delimiter=',') # This is known to be a 2-columns, many rows array
X = data[:,:-1]
y = data[:,-1]
因此，据我所知，X是一个1列数组，用于捕获data的除最后一个列之外的所有列（因此实际上仅捕获第一列）和y是一个仅捕获data的最后一列的1列数组。
我的问题是为什么不这样写代码：
X = data[:,0]
y = data[:,1]
会不会更清晰/更清洁？
答案 0 :(得分：1)
(n, 1)是X = data[:, :1]
X = data[:, 0, None]
X = data[:, 0].reshape(-1, 1)
的2D数组，因为切片可保留维数。其他措词可能是
y (n,)是一个// -----------------------------------------
// COUNT AMOUNT UNTIL CUSTOMER REACHES NEXT TIER
function amount_until_tier() {
$count = count_orders();
$tier_name = tier_status();
//$amount_until = abs($count - $next_tier);
if ( $count >= 50 ) {
echo 'You\'ve made it! You\'re VIP. Expect random rewards.';
} else {
//echo 'You need <strong>' . $amount_until . '</strong> more orders to reach <strong>' . $tier_name . '</strong>';
}
$the_digits = ['5','15','30','50'];
$showModal = false;
if (in_array($count, $the_digits)) {
if (!isset( $_COOKIE["tier_advance"] )) {
$showModal= true;
} else {
if ($_COOKIE["tier_advance"] != "$count") {
$showModal = true;
} else {
// echo "false because tier_advance !== count
}
}
} else {
// echo "false because not in the_digits";
}
if ($showModal) {
echo '<script>
jQuery(window).on("load",function(){
jQuery("#tier_advance").modal("show");
});
jQuery(document).on("click", "#tier_confirm", function(){
// Set a cookie
Cookies.set("tier_advance", "' . $count . '", { expires: 356 });
});
</script>
<!-- BEGIN Share Modal -->
<div class="modal fade" id="tier_advance" tabindex="-1" role="dialog">
<div class="modal-dialog modal-dialog-centered" role="document">
<div class="modal-content">
<div class="modal-header text-center">
<h5>CONGRATULATIONS!' . $count . '</h5>
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
<div class="modal-body text-center">
<p>You are now a <strong class="all-caps"> ' . $tier_name . ' </strong>tier customer!</p>
<p>Expect some sweet rewards to start coming your way!</p>
</div>
<div class="modal-footer modal-footer-centered">
<button id="tier_confirm" type="button" class="btn btn-secondary" data-dismiss="modal">Awesome, thanks!</button>
</div>
</div>
</div>
</div>
<!-- END Share Modal -->';
}
}
add_action('wp_head', 'amount_until_tier');
一维数组。
这些形状对于用于实现回归的线性代数很重要。