reticulate::repl_python()

## Estimating the number of components in Bayesian settings
from selenium import webdriver
from selenium.webdriver.common.keys import Keys
from selenium.webdriver.common.by import By
from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
import time
import numpy

lnk  = 'https://www.coursera.org/learn/mixture-models/exam/9IYM3/estimating-the-number-of-components-in-bayesian-settings'
lnk2 = 'https://www.coursera.org/learn/mixture-models/exam/9IYM3/estimating-the-number-of-components-in-bayesian-settings/attempt'

# Download the `geckodriver` webdriver.
driver = webdriver.Firefox(executable_path=r'/home/englianhu/Documents/geckodriver')
driver.get(lnk2)
#assert 'Python' in driver.title
wait   = WebDriverWait(driver, 5)
elem   = driver.find_element_by_xpath('//*[@id="email"]')
elem.send_keys('englianhu@gmail.com')

wait   = WebDriverWait(driver, 1)
elem   = driver.find_element_by_xpath('//*[@id="password"]')
elem.send_keys('**********')
#elem.clear()
elem.send_keys(Keys.RETURN)

wait   = WebDriverWait(driver, 5)
elem   = driver.find_element_by_xpath('/html/body/div[6]/div/div[3]/div[1]/button')
elem.send_keys(Keys.RETURN)

for n in list(numpy.arange(0, 10000, 0.5)):
  ## assessment question
  elem   = driver.find_element_by_xpath(
    '//*[@id="text-input-ZTDYZx9hEeqF4xJzBvIAyQ-input"]')
  elem.send_keys(str(n))
  
  elem   = driver.find_element_by_xpath(
    '//*[@id="text-input-UlGqjR-lEeqKlBLH7WtknQ-input"]')
  elem.send_keys(str(n))
  
  elem   = driver.find_element_by_xpath(
    '//*[@id="text-input-WhtVnCApEeqqhA61a6gg2w-input"]')
  elem.send_keys(str(n))
  
  elem   = driver.find_element_by_xpath(
    '//*[@id="text-input-giU7KiAoEeqFkg4D2xLqww-input"]')
  elem.send_keys(str(n))
  
  wait   = WebDriverWait(driver, 1)
  elem   = driver.find_element_by_xpath(
    '/html/body/div[6]/div/div/div/div[2]/div[2]/div/div[2]/div/div[3]/div/div[1]/div[1]/div/div[1]/label/input')
  elem.click()
  
  wait   = WebDriverWait(driver, 1)
  elem   = driver.find_element_by_xpath(
    '/html/body/div[6]/div/div/div/div[2]/div[2]/div/div[2]/div/div[3]/div/div[2]/button[2]/span')
  elem.click()
  
  #window_after = driver.window_handles[0]
  #driver.switch_to.window(window_after)
  #elem   = driver.switchTo().frame(driver.find_element_by_xpath('/html/body/div[6]/div/div/div/div[2]/div[2]/div/div[2]/div/div[3]/div/div[1]/div[1]/div/div[1]/label/input')
  
  #get current window handle
  p1      = driver.current_window_handle
  driver.switch_to.window(p1)
  #wait   = WebDriverWait(driver, 5)
  #driver.switch_to_active_element()
  
  #driver.switch_to.window(driver.window_handles[-1])
  #wait   = WebDriverWait(driver, 5)
  #driver.implicitly_wait(10)
  #driver.findelement(by.linktext('test').click();
  #elem   = wait.until(ExpectedConditions.elementToBeClickable(By.XPATH('/html/body/div[6]/div/div/div/div[2]/div[2]/div/div[1]/div/div/div/div[2]/div[1]/div/button/span')))
  #elem   = wait.until(EC.presence_of_element_located(By.XPATH, '/html/body/div[6]/div/div/div/div[2]/div[2]/div/div[1]/div/div/div/div[2]/div[1]/div/button/span'))
  elem   = driver.find_element_by_xpath(
    '/html/body/div[6]/div/div/div/div[2]/div[2]/div/div[1]/div/div/div/div[2]/div[1]/div/button/span')
  elem.click()
  
  #wait   = WebDriverWait(driver, 5)
  #driver.implicitly_wait(2)
  #driver.refresh()
  #driver.get(lnk)
  time.sleep(8)
  #driver.refresh()
  ### wait   = WebDriverWait(driver, 1)
  #p2      = driver.current_window_handle
  #driver.switch_to.window(p2)
  #driver.refresh()
  #driver.get('https://www.coursera.org/learn/mixture-models/exam/9IYM3/estimating-the-number-of-components-in-bayesian-settings')
  #wait   = WebDriverWait(driver, 5)
  #elem   = wait.until(EC.presence_of_element_located(
  #  By.XPATH, '/html/body/div[3]/div/div/div[2]/div/div[2]/div[2]/div[2]/main/div/div[3]/div[3]/div/div/div/button/span'))
  #wait   = WebDriverWait(driver, 10)
  #time.sleep(10)
  driver.switch_to.active_element()
  elem   = driver.find_element_by_xpath(
    '/html/body/div[3]/div/div/div[2]/div/div[2]/div[2]/div[2]/main/div/div[3]/div[3]/div/div/div/button/span')
  elem.click()
  #driver.implicitly_wait(10)
  #p      = driver.current_window_handle
  #driver.switch_to.window(p)
  
  #while True: 
  # try:
      #driver.execute_script("arguments[0].click();")
  #    elem   = driver.find_element_by_xpath(
  #      '/html/body/div[3]/div/div/div[2]/div/div[2]/div[2]/div[2]/main/div/div[3]/div[3]/div/div/div/button/span')
  #    elem.click()
  #    break
  # except: 
  #    time.sleep(1)
  #    driver.refresh()

#assert 'No results found.' not in driver.page_source
#driver.close()

在for loop时才会出现无止境读取的空白页面，尝试driver.get()、driver.refresh()、wait.until()都无效，因为网址一样，而内容不一样，driver.switch_to.active_element(...)和driver.switch_to.frame()怎么使用？

#driver.switch_to.active_element()
  elem   = driver.find_element_by_xpath(
    '/html/body/div[3]/div/div/div[2]/div/div[2]/div[2]/div[2]/main/div/div[3]/div[3]/div/div/div/button/span')
  elem.click()