类型相关
类型
- int
- float
- bool
- string
- NoneType
|
1 |
type() |
类型转换
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1 2 3 |
int() float() str() |
操作
|
1 2 3 4 5 6 7 |
i+j i-j i*j i/j i//j 整除 i%j i**j 幂 |
String
|
1 2 3 4 5 6 7 8 |
s = "abcdefgh" s[::-1] // hgfedcba s[3:6] // def s[-1] // h |
分支相关
比较运算符
|
1 2 3 4 5 6 |
> >= < <= == != |
逻辑运算符
- not a
- a是True，结果是False
- a是False, 结果是True
- a and b
- a和b同为True，结果为True
- a or b
- a和b有一个为True，结果为True
输入输出
|
1 |
input() |
控制流1
控制流2
|
1 2 3 4 5 |
for i in range(6, 10): print(i) for i in range(1, 10, 2): print(i) |
文件
|
1 2 3 4 5 6 7 8 9 10 |
nameHandle = open('kids', 'w') for i in range(2): name = input("input a name: ") nameHandle.write(name + '\') nameHandle.close() nameHandle = open('kids', 'r') for line in nameHandle: print(line) nameHandle.close() |
元组相关
|
1 2 3 4 5 6 7 |
// 别名 hot = ['red', 'yellow'] hto = hot // 克隆 cool = ['blue', 'grey'] cloo = cool[:] |
函数相关
|
1 2 3 4 5 6 7 8 9 10 11 12 13 |
def applyToEach(L, f): for i in range(len(L)): L[i] = f(L[i]) applyToEach(L, abs) applyToEach(L, int) applyToEach(L, fact) // map map(abs, [1,-2,3,4]) for elt in map(abs, [1,-2,3,4]): print(elt) // 1,2,3,4 |
|
1 2 3 4 5 6 7 |
L1 = [1, 26, 33] L2 = [2, 55, 9] for elt in map(min, L1, L2): print(elt) // 1, 26, 9 |
字典相关
|
1 2 3 4 5 6 7 |
def fib_dic(n, d): if n in d: return d[n] else: ans = fib_dic(n-1, d) + fib_dic(n-2, d) d[n] = ans return ans |
变量相关
|
1 2 |
// 全局变量 num = 0 |
|
1 2 3 4 |
def fib(n): global num num += 1 print(num) |
异常相关
异常
|
1 2 3 4 5 6 7 8 9 10 |
def get_retios(L1, L2): ratios = [] for index = range(len(L1)): try: ratios.append(L1[index]/float(L2[index])) except ZeroDivisionError: ratios.append(float('NaN')) except: raise ValueError('test') return ratios |
断言
|
1 2 3 |
def avg(grades): assert not len(grades) == 0, return sum(grades)/len(grades) |
类相关
|
1 2 3 4 5 6 7 8 9 10 |
class Coordinate(object): tag = 1 def __init__(self, x, y): self.x = x self.y = y def dist(self, other): a = (self.x - other.x)**2 b = (self.y - other.y)**2 return (a+b)**0.5 |
绘图相关
PYLAB
Code
近似解
|
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 |
cube = 29 epsilon = 0.01 guess = 0.0 increment = 0.01 num_guesses = 0 while abs(guess**3 - cube) >= epsilon and guess <= cube: guess += increment num_guesses += 1 print('num_guessses = ', num_gussess) if abs(guess**3 - cube) >= epsilon: print('Failed on cube root of', cube) else: print(guess, 'is close to the cube root of', cube) |
斐波那契
|
1 2 3 4 5 |
def fibnaci(x): if x == 0 or x == 1: return 1 else: return fibnaci(x-1) + fibnaci(x-2) |
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