小编rau*_*ira的帖子

从python函数中产生时如何连接两个项？

基本情况:

import itertools

def test():
    for number in range(0,10):
        yield number

list(test()) # [0...9]

如果我想同时得到number它的正方形怎么办？number**2

import itertools

def test():
    for number in range(0,10):
        yield itertools.chain.from_iterable([
            number,number*2
        ])

list(test()) 

# [0,0,1,1,2,4,3,9,...] pretended
# <itertools.chain at 0x135decfd0> ... what I got

但是,itertools.chain.from_iterable([generator1, generator2])从外部做,给出了预期的结果.

def first_list():
    for number in range(0,5):
        yield number

def second_list():
    for number in range(5,10):
        yield number

list(itertools.chain.from_iterable([first_list(), second_list()]))

我需要获取动态内容，该内容由 ajax js 调用加载。

我真的不知道如何使用 PyQt，但我希望我能做到这一点。HTML是这样的：

<a href="#" id="id" onclick="A4J.AJAX.Submit('j_id0:j_id1:j_id110',event,{'similarityGroupingId':'j_id0:j_id1:j_id110:j_id582:0:j_id584'});return false;">NETHERLANDS</a>`

我可以使用以下简单代码使用 PyQt 呈现页面：

def render(source_html):

    import sys
    from PyQt5.QtCore import QEventLoop
    from PyQt5.QtWidgets import QApplication
    from PyQt5.QtWebEngineWidgets import QWebEngineView

    class Render(QWebEngineView):
        def __init__(self, html):
            self.html = None
            self.app = QApplication(sys.argv)
            QWebEngineView.__init__(self)
            self.loadFinished.connect(self._loadFinished)
            self.setHtml(html)

            while self.html is None:
                self.app.processEvents(QEventLoop.ExcludeUserInputEvents | QEventLoop.ExcludeSocketNotifiers | QEventLoop.WaitForMoreEvents)
            self.app.quit()

        def _callable(self, data):
            self.html = data

        def _loadFinished(self, result):
            self.page().toHtml(self._callable)

    return Render(source_html).html

import requests
sample_html = requests.get('https://riverbankcomputing.com/software/pyqt/').text
print(render(sample_html))

我如何运行“onclick”并获取内容？

我有一个ADT如下:

sealed trait Tree[A]
case object EmptyTree extends Tree[Nothing]
case class Leaf[A](value: A) extends Tree[A]
case class Node[A](op: Seq[A] => A, branches: Tree[A]*) extends Tree[A]

当我尝试构建一个随机创建树的函数时,我遇到了EmptyTree的问题,类型系统不允许通过

  def create(acc: Tree[A], currentDepth: Int): Tree[A] = currentDepth match {
    case maxDepth => Leaf(terminalSet(r.nextInt(terminalSet.length)))
    case 0 => {
      val op_pos = r.nextInt(fSetLength)
      val branches: Seq[Tree[A]] = for (i <- 0 to r.nextInt(fSetLength)) yield create(EmptyTree, currentDepth+1)
      Node(functionSet(op_pos)._1, branches:_*)
    }
    case _ => {
      if (r.nextFloat() <= probF) {
        val op_pos = r.nextInt(fSetLength)
        val branches = …

在scala我不允许执行以下操作:

case class Terminal(value: Double, name: String = value.toString)

而且我也不能这样做:

case class Terminal(value: Double)(name: String = value.toString)

我理解构造函数不支持多参数列表方法.

有没有办法在apply方法中定义才能使这成为可能？

预期行为:

Terminal(1.0) // => Terminal (1.0, "1.0")

在scala中,如何创建通用函数来执行以下操作:

f: List[A] ==> List[Option[A]]