Chapter 15 finished.

15-time/README.md

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+# time
+<pre>
+import time
+now = time.time()
+</pre>
+
+# datetime
+1. import datetime
+2. datetime.datetime.now()
+3. datetime.datetime.fromtimestamp(time.time())
+4. datetime.timedelta()
+

15-time/about30YearsLater.py

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+import datetime
+
+aboutThirtyYears = datetime.timedelta(days=365*30)
+print(datetime.datetime.now() + aboutThirtyYears)

15-time/calcProd.py

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+import time
+startTime = time.time()
+# Calculate the product of the first 100,000 numbers.
+product = 1
+for i in range(1, 100000):
+    product = product * i
+endTime = time.time()
+print('The result is %s digits long.' % (len(str(product))))
+print('Took %s seconds to calculate.' % (endTime - startTime))

15-time/countdown.py

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+#! python3
+# countdown.py - A simple countdown script.
+
+import time, subprocess
+
+timeLeft = 10
+while timeLeft > 0:
+    print(timeLeft, end='')
+    time.sleep(1)
+    timeLeft = timeLeft - 1
+
+# At the end of the countdown, play a sound file.
+subprocess.Popen(['start','alarm.wav'], shell=True)

15-time/multidownloadXkcd.py

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+#! python3
+# multidownloadXkcd.py - Downloads XKCD comics using multiple threads.
+
+import requests, os, bs4, threading
+os.makedirs('xkcd', exist_ok=True) # store comics in ./xkcd
+
+def downloadXkcd(startComic, endComic):
+    for urlNumber in range(startComic, endComic):
+        # Download the page.
+        print('Downloading page http://xkcd.com/%s...' % (urlNumber))
+        res = requests.get('http://xkcd.com/%s' % (urlNumber))
+        res.raise_for_status()
+
+        soup = bs4.BeautifulSoup(res.text)
+
+        # Find the URL of the comic image.
+        comicElem = soup.select('#comic img')
+        if comicElem == []:
+            print('Could not find comic image.')
+        else:
+            comicUrl = comicElem[0].get('src')
+            # Download the image.
+            print('Downloading image %s...' % (comicUrl))
+            res = requests.get(comicUrl)
+            res.raise_for_status()
+
+            # Save the image to ./xkcd
+            imageFile = open(os.path.join('xkcd', os.path.basename(comicUrl)), 'wb')
+            for chunk in res.iter_content(100000):
+                imageFile.write(chunk)
+            imageFile.close()
+
+# Create and start the Thread objects.
+downloadThreads = [] # a list of all the Thread objects
+for i in range(0, 1400, 100): # loops 14 times, creates 14 threads
+    downloadThread = threading.Thread(target=downloadXkcd, args=(i, i + 99))
+    downloadThreads.append(downloadThread)
+    downloadThread.start()
+
+# Wait for all threads to end.
+for downloadThread in downloadThreads:
+    downloadThread.join()
+print('Done.')

15-time/stopwatch.py

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+#! python3
+# stopwatch.py - A simple stopwatch program.
+
+import time
+
+# Display the program's instructions.
+print('Press enter to begin. Afterwards, press ENTER to "click" the stopwatch. Press Ctrl-C to quit.')
+input() # press Enter to begin
+print('Started.')
+startTime = time.time() # get the first lap's start time
+lastTime = startTime
+lapNum = 1
+
+# Start tracking the lap times.
+try:
+    while True:
+        input()
+        lapTime = round(time.time() - lastTime, 2)
+        totalTime = round(time.time() - startTime, 2)
+        print('Lap #%s: %s (%s)' % (lapNum, totalTime, lapTime), end='')
+        lapNum += 1
+        lastTime = time.time() # reset the last lap time
+except KeyboardInterrupt:
+    # Handle the Ctrl-C exception to keep its error message from displaying.
+    print('\nDone.')

15-time/thousandDaysLater.py

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+import datetime
+
+dt = datetime.datetime.now()
+thousandDays = datetime.timedelta(days=1000)
+print(dt + thousandDays)

15-time/threadDemo.py

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+import threading, time
+print('Start of program.')
+
+def takeANap():
+    time.sleep(5)
+    print('Wake up!')
+
+threadObj = threading.Thread(target=takeANap)
+threadObj.start()
+
+print('End of program.')

15-time/threadWithParameters.py

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+import threading
+
+threadObj = threading.Thread(target=print, args=['Cats', 'Dogs', 'Frogs'],
+    kwargs={'sep': ' & '})
+threadObj.start()
+

15-time/timeSleep.py

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+import time
+
+for i in range(3):
+	print('Tick')
+	time.sleep(1)
+	print('Tock')
+	time.sleep(1)
+

15-time/until.py

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+import datetime
+import time
+tm = datetime.datetime(2017, 7, 8, 8, 27, 0)
+while datetime.datetime.now() < tm:
+    time.sleep(1)
+print('Done')