Contents:¶
1. Basic python¶
- Statement Assignment
- print()
- list/list slice
- for loop + list (range)
- while loop
- str()
- function
2. Third-party modules¶
Check Modules Exist¶
You don't need to install time/datetime/threadin/subprocess, because they are in standard library.¶
Without Error Massage!!¶
import time
import datetime
import threading
import subprocess
Let's Start!¶
- Unix epoch is a time reference commonly used in programming
- Start calculated the seconds form 12 AM on January 1, 1970
- The time.time() function returns the number of seconds since that moment as a float value
In [1]:
import time
time.time()
Out[1]:
In [12]:
s1 = time.time()
result = 1
for i in range(1, 10):
result = result * i
print(i, result)
s2 = time.time()
duration = s2 - s1
print('Cost time : %s' %(duration))
TIME.SLEEP() Function¶
In [18]:
import time
time.sleep(5)
print('Wakeup Now!')
In [21]:
import time
now = time.time()
round(now)
Out[21]:
In [20]:
round(now, 1)
Out[20]:
In [22]:
round(now, 3)
Out[22]:
Datetime Module¶
- Display a date in a more convenient format
- Can do arithmetic with dates (e.g. : show the day of 30 days ago)
In [23]:
import datetime
datetime.datetime.now()
Out[23]:
In [27]:
now = datetime.datetime.now()
now.year, now.month, now.day, now.hour, now.minute, now.second
Out[27]:
In [29]:
datetime.datetime.fromtimestamp(1000000)
Out[29]:
In [30]:
datetime.datetime.fromtimestamp(time.time())
Out[30]:
Datetime Could Apply with Comparison¶
In [31]:
NewYear = datetime.datetime(2018, 1, 1)
ChristmasDay = datetime.datetime(2018, 12, 25)
In [33]:
NewYear == ChristmasDay
Out[33]:
In [32]:
NewYear < ChristmasDay
Out[32]:
In [34]:
NewYear != ChristmasDay
Out[34]:
In [39]:
delta = datetime.timedelta(days=10, hours=10, minutes=10, seconds=10)
delta.days, delta.seconds
Out[39]:
In [40]:
delta.total_seconds()
Out[40]:
Notice!¶
- There is no month or year keyword argument
Datetime Calculate with Operators¶
In [42]:
import datetime
dt = datetime.datetime.now()
dt
Out[42]:
In [43]:
thousandDays = datetime.timedelta(days=1000)
In [44]:
dt + thousandDays
Out[44]:
In [45]:
dt + thousandDays*10
Out[45]:
Converting datetime Objects into Strings¶
| Strftime Directive | Meaning |
|---|---|
| %Y | Year with century, as in '2014' |
| %y | Year without century, '00' to '99' (1970 to 2069) |
| %m | Month as a decimal number, '01' to '12' |
| %B | Full month name, as in 'November' |
| %b | Abbreviated month name, as in 'Nov' |
| %d | Day of the month, '01' to '31' |
| %j | Day of the year, '001' to '366' |
| %w | Day of the week, '0' (Sunday) to '6' (Saturday) |
| %A | Full weekday name, as in 'Monday' |
| %a | Abbreviated weekday name, as in 'Mon' |
| %H | Hour (24-hour clock), '00' to '23' |
| %I | Hour (12-hour clock), '01' to '12' |
| %M | Minute, '00' to '59' |
| %S | Second, '00' to '59' |
| %p | 'AM' or 'PM' |
.strftime(format)¶
In [53]:
import datetime
oct14st = datetime.datetime(2018, 10, 14, 17, 2, 3)
oct14st.strftime('%Y/%m/%d %H:%M:%S')
Out[53]:
In [54]:
oct14st.strftime('%I:%M %p')
Out[54]:
In [55]:
oct14st.strftime("%B of '%y")
Out[55]:
In [56]:
datetime.datetime.strptime('October 14, 2018', '%B %d, %Y')
Out[56]:
In [57]:
datetime.datetime.strptime('2018/10/14 01:02:03', '%Y/%m/%d %H:%M:%S')
Out[57]:
In [58]:
datetime.datetime.strptime("October of '18", "%B of '%y")
Out[58]:
Multithreading¶
import time, datetime
startTime = datetime.datetime(2029, 10, 31, 0, 0, 0)
while datetime.datetime.now() < startTime:
time.sleep(1)
print('Program now starting on Halloween 2029')
- For the example above, your program cannot do anything while waiting till 2029/10/31
- This is because Python programs by default have a single thread of execution
For Avoiding this Problem, Try "Multithreaded Program" Now!¶
Normal Program V.S. Threading Program¶
Normal Program¶
Threading Program¶
In [68]:
print('Cats', 'Dogs', 'Frogs', sep=' & ')
In [70]:
import threading
threadObj = threading.Thread(target=print('Cats', 'Dogs', 'Frogs', sep=' & '))
threadObj.start()
In [71]:
import threading
threadObj = threading.Thread(target=print, args=['Cats', 'Dogs', 'Frogs'], kwargs={'sep': ' & '})
threadObj.start()
Notice!¶
- The concurrency issues happen when threads read and write variables at the same time.
- To avoid concurrency issues, never let multiple threads read or write the same variables.
Launching Other Programs from Python¶
Start an external program from your Python script¶
On Windows¶
Right-click the application’s Start menu item and select Properties to view the application’s filename.
On OS X¶
CTRL-click the application and select Show Package Contents to find the path to the executable file.
Create an New Text File and Open with Defualt Application¶
In [6]:
fileObj = open('Docs\D3_01.txt', 'w')
fileObj.write('Hello world!')
fileObj.close()
import subprocess
subprocess.Popen(['start', 'Docs\D3_01.txt'], shell=True)
Out[6]:
Running Other Python Scripts¶
Create an New Python File and Running Script¶
In [7]:
fileObj = open('Docs\D3_02.py', 'w')
fileObj.write('print("Hello Olly!")')
fileObj.close()
subprocess.Popen([r'C:\Users\Olly\AppData\Local\Programs\Python\Python35\python.exe', 'Docs\D3_02.py'])
Out[7]:
Project : Simple Countdown Program¶
In [1]:
import time, subprocess
timeLeft = 5
while timeLeft > 0:
print(timeLeft, end='>')
time.sleep(1)
timeLeft = timeLeft - 1
subprocess.Popen(['start', 'Docs/Sleep_Away.mp3'], shell=True)
Out[1]:
Exercise¶
Answer¶
In [38]:
import time, datetime, subprocess
now = datetime.datetime.now()
print(now)
while now.minute!=7:
time.sleep(1)
now = datetime.datetime.now()
print(str(now.minute)+':'+str(now.second), end='>')
subprocess.Popen(['start', 'Imgs/D3_08.GIF'], shell=True)
Out[38]:
