Python

1. 关于Python 的if-else语句。要注意if和else后面都要加“：”

def make_decision(L1, L2, L3, L4):

    if L1+L2>L3+L4:
        return "L" 
    else:

        return "R"

2.绝对值 abs()

3.如果只想用list当中的一部分，可以用

         for item in my_list[:3]:
             print("item is", item)

        for item in my_list[2:4]:

            print("item is", item)

       结果是，因为4-2=2，所以只有两个

          item is 3          item is a

4.enumerate功能

  for i, item in enumerate(my_list):   print("item number", i, "is", item)

得到的结果是：
item number 0 is 1item number 1 is 2item number 2 is 3item number 3 is aitem number 4 is bitem number 5 is c
5.list有index的方法
for item in my_list:    index = my_list.index(item)    print("item", item, "has index", index)
6.list表的遍历
numbers_0_to_9 = [x for x in range(10)]print("Numbers 0 to 9", numbers_0_to_9)
结果是Numbers 0 to 9 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
odds = [x for x in range(10) if x % 2 == 1]print("Odds          ", odds)
结果是Odds           [1, 3, 5, 7, 9]
7.关于namedtuple的使用
from collections import namedtuplePerson = namedtuple("Person", ["name", "age", "gender"])people = [    Person("Andy", 30, "m"),    Person("Ping", 1, "m"),     Person("Tina", 32, "f"),    Person("Abby", 14, "f"),    Person("Adah", 13, "f"),    Person("Sebastian", 42, "m"),    Person("Carol" , 68, "f"),]# first, let's show how this namedtuple works.andy = people[0]print("name:  ", andy.name)print("age:   ", andy.age)print("gender:", andy.gender)
male_names = [person.name for person in people if person.gender=="m"]print("Male names:", male_names)
teen_names = [p.name for p in people if 13 <= p.age <= 18 ]print("Teen names:", teen_names)
8.关于random.choice的使用
roll = rd.choice([1,2,3,4,5,6])
返回list当中任意一个数
9.Python可以直接顺序使用大于号，小于号
Y = 7
if 5 < Y < 10:
    print("Y is between 5 and 10")
else: 
    print("Y is not between 5 and 10")
10.如何使用if语句进行
if True:    print("True is always True!")
if False:    print("This will never be printed") 
11.elif的用法
X = 4if X < 5:    print("X is a small number")elif X < 20:    print("X is a medium sized number")else:    print("X is a big number") 
12.isinstance的用法
这个内置函数是为了判断变量的类型
sqr_root_2 = math.sqrt(2)is_sqr_root_2_an_integer = isinstance(sqr_root_2, int)print("Is square root two an integer?", is_sqr_root_2_an_integer)
13.建立二维list的方法，注意list不可用list[i,j]遍历，赋值时也只可使用list[i][j]
for i in range(self.grid_size[0]):            entry = []            for j in range(self.grid_size[1]):                entry.append(probability)            self.grid.append(entry)return self.grid