Python 101

體驗半隻腳踏入 cs 世界的日常

01 Intro
https://hackmd.io/@lhsueh1/python101_intro

02 Accumulation

Boolean

		and	or
1	0	False	True
1	1	True	True
0	0	False	False
0	1	False	True

range
range(開頭, 結尾, 間隔)

conditional

if (a):
    print("a is True!")
elif(b):
    print("b is True")
else:
    print("no one is True")

for loop

for i in range(10):
    print(i) # i-> 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

while loop

while(run_below_if_true):
    print("forever")
    if(condition):
        break #ends while loop

random

import random
random.randrange(10) #random number between 0-9

https://hackmd.io/@lhsueh1/python101_Accumulation

03 Function

function

def sum_of_square(a, b):
    ans = ((a + b)**2) - (2*ab)
    return ans

def main(): #main function, good practice
    a = sum_of_square(2, 5)
    print(a) #will print 29
    
main()

https://hackmd.io/@lhsueh1/python101_Function

04 Immutable Data Types

string

myString = "Hello World"
len(myString) #get length
# strings are indexable!
print(myString[0]) #prints 'H'

tuple

a = (13, 5)
# tuples are indexable!

https://hackmd.io/@lhsueh1/HyxB7ac8j

Indirect proof & 3n + 1
https://hackmd.io/@lhsueh1/rkfthUxwj

05 List

List

mylist = [1, 2, 3, 4]
# lists are indexable! 
print(mylist[0]) #print first element
len(mylist) #get length
mylist.append(4) # add 4 to the end of the list
mylist.pop() # remove the last element of the list

https://hackmd.io/@lhsueh1/BJ7Z3VFvj

Recursion
https://hackmd.io/@lhsueh1/HyUdJhtvj

Turtle
https://hackmd.io/@lhsueh1/S1zzzYzds

06 Dictionary

mydict = {"twelve":12, "six":6, "twenty":20}
#前者 key 後者 value

print(mydict["six"]) #access through key, will print 6
print(mydict.get("sixx")) #safe way to access through key
mydict["one"] = 1 #新增

for i, j in mydict.items(): #access with loop
    print(j, i) #i: key, j: value

https://hackmd.io/@lhsueh1/SyctFNRts

07 File I/O & module

• write

file = open("test.txt", "w")
file.write("hi")
file.close()

• append

file = open("test.txt", "a")
file.write("hi_2")
file.close()

• for loop 讀法 (一次拿一行

fref = open("test.txt", "r")
for line in fref:
    print(line)
fref.close()

• readline() 讀法 （一次一行

fref = open("test.txt", "r")
print(fref.readline())
print(fref.readline())
print(fref.readline())
fref.close()

• readlines() 讀法（一次全部

fref = open("test.txt", "r")
print(fref.readlines())
fref.close()

• read() 讀法（一次全部

fref = open("test.txt", "r")
print (fref.read())
fref.close()

https://hackmd.io/@lhsueh1/HJ5YFECKs

JSON <3
https://hackmd.io/@lhsueh1/BygVYReno

08 Class

class Rectangle:
    def __init__(self):
        self.width = 10
        self.height = 10
        self.color = "red"
    def get_area(lines="The area is... "):
        return lines + str(self.width * self.height)

r = Rectangle()
r.width = 20
print(r.get_area())  # The area is... 200
r.height = 1
print(r.get_area("->>")) # ->>20

https://hackmd.io/@lhsueh1/B17iF0ghi

Pygame
https://hackmd.io/@lhsueh1/BJM6ITBTs

What's next
https://hackmd.io/@lhsueh1/r1mRinrni

Not included

• Exceptions
• Network
• Inheritance
• Testing
• Git
• Basic Linux
• …