1. About loop
· Indentation means these sentences or this sentence belong(s) to this loop.Such as,
magicians=['david','joe','kite','john']
for magician in magicians:# loop
print(magician.title() + ', you have been invited.')
print("I can't wait to see your next trick, "+ magician.title() + '\n')
· After loop, a non-indented sentence means it doesn't belongs to this loop.
· DO NOT FORGET THE":" AFTER YOU WRITE THE FOR xxx
2. About numerical list
· Use range()
o If you want to print one to five, you need to use range(1,6).DO NOT FORGET IT.
For example,
for value in range(1,6):
print(value)
range(a,b,m), a means the start point, b means the end point, and m means step length.
For example,
o After you input range(1,6,2), you can see [1,3,5].
o Use range() and list() to make up a list
For example,
numbers=list(range(1,11))
print(numbers)
If you use list(range(1,11,2)), you can see [1,3,5,7,9].
power operation just like a**2,using **.
· Some simple functions
· min(digits) means figure out the mnimum.
· max(digits) means figure out the max number.
· sum(digits) means figure out the sum.
· List Comprehensions(列表解析)
For example,
data=[valu**3 for valu in range(2,12,2)]
print(data)
Using part of list: Slice
· Some ways:
o print str[0:3] #截取第一位到第三位的字符
o print str[:] #截取字符串的全部字符
o print str[6:] #截取第七个字符到结尾
o print str[:-3] #截取从头开始到倒数第三个字符之前
o print str[2] #截取第三个字符
o print str[-1] #截取倒数第一个字符
o print str[::-1] #创造一个与原字符串顺序相反的字符串
o print str[-3:-1] #截取倒数第三位与倒数第一位之前的字符
o print str[-3:] #截取倒数第三位到结尾
o print str[:-5:-3] #逆序截取
· Copy list:
If we want to copy the elements of one list to another list, we need to do as followed:
my_foods = ['apple','banana','cake']
friend_foods = my_foods[:]#如果没有[:]那就意味着只是将my_foods的地址指向friend_foods，这样的话，如果更改前者元素后者也会更改
print(my_foods)
print(friend_foods)
my_foods.append("water melon")
friend_foods.append("monga")
print(my_foods)
print(friend_foods)
We can see that firend_foods is different from my_foods.
Tuple（元组）
list is unchangeable, so sometime we need a tuple. Tuple is changeable.
define a tuple like this: dimensions=(200,50). We do not use [].
The elements of tuple cannot be changed, but we can assign.
In addition , tuple is as same as list.
