- from numpy import
- import operator
- def spliting():
- print('--'20)
- '''
- def greatDataSet():
- group = array([(1.0,1.1),(1.0,1.0),(0,0),(0,0.1)])
- labels = ['A','A','B','B']
- return group, labels
- print(random.rand(4,4)) # 生成随机数
- randMat = mat(random.rand(4,4))
- print(randMat) # 转化为矩阵
- invRandMat = randMat.I # 实现矩阵求逆
- print(randMat invRandMat) # 矩阵与逆矩阵相乘的结果
- myEye = randMat invRandMat
- print(myEye - eye(4)) # eye(4) 创建单位矩阵
- '''
- print(int(3.14)) # 3
- print(float(3)) # 3.0
- print(str('a\tb')) # a b
- print(repr('a\tb')) # 'a\tb'
- num = 1/3.0
- print('%e' % num) # 3.333333e-01
- print('%4.2f' % num) # 0.33
- print('{
- 0:4.2f
- }'.format(num)) # 0.33
- print(1 == 2 <3) # False
- print(1 == 1 < 3) # True
- from future import devision
- print(10/4) # 2.5
- print(10//4) # 2
- print(10/4.0) # 2.5
- print(10//4.0) # 2.0
- import math
- print(math.floor(4.2)) # 4
- print(math.floor(4.6)) # 4
- print(math.floor(-4.6)) # -5
- print(math.floor(-4.2)) # -5
- print(math.trunc(4.2)) # 4
- print(math.trunc(4.6)) # 4
- print(math.trunc(-4.6)) # -4
- print(math.trunc(-4.2)) # -4
- print(round(4.2)) # 4
- print(round(4.6)) # 5
- print(round(-4.2)) # -4
- print(round(-4.6)) # -5
- spliting()
- print(0o1,0o20) # 1,16
- print(0x01,0x10) # 1,16
- print(0b01,0b10000) # 1,16
- print(oct(64)) # 0o100
- print(bin(64)) # 0b1000000
- print(hex(64)) # 0x40
- print(int('64')) # 64
- print(int('100',8)) # 64
- print(int('1000000',2))# 64
- print(eval('64')) # 64
- print(eval('0o100')) # 64
- print(eval('0x40')) # 64
- print('{
- 0:o
- },{
- 1:x
- },{
- 2:b
- }'.format(64,64,64)) # 100,40,1000000
- print('%x %o %X' %(255,64,255))
- x = 1
- print(bin(x)) # 0b1
- print(bin(2)) # 0b10
- print(x<<2,bin(x<<2)) # 4, 0b100
- print(x | 2 ,bin(x | 2)) # 3 0b11
- print(x & 2,bin(x & 2)) # 0 0b0
- x = 0xff
- print(bin(x)) # 0b11111111
- print(x^0b10101010) # 85
- print(bin(x^0b10101010)) # 0b1010101
- print(int('1010101',2)) # 85
- print(hex(85)) # 0x55
- x = 99
- print(bin(99),x.bit_length()) # 0b1100011 7
- print(bin(256),(256).bit_length()) # 0b100000000 9
- print(len(bin(256))) # 11
- print(len(bin(99))) # 9
- print((99).bit_length()) # 7
- spliting()
- import math
- print(math.pi,math.e) # 3.141592653589793 2.718281828459045
- print(math.sin(2 * math.pi /180)) # 0.03489949670250097
- print(math.sqrt(144),math.sqrt(2)) # 12.0 1.4142135623730951
- print(pow(2,4),2**4)# 16 16
- print(abs(-45.4),sum((3,4,5))) # 45.4 12 sum 作用一个数字序列
- print(min(1,3,4,2),max(3,1,4,2)) # 1 4
- print(0.1+0.1+0.1-0.3) # 5.551115123125783e-17
- import decimal
- print(decimal.Decimal('0.1')+decimal.Decimal('0.1')+decimal.Decimal('0.1')-decimal.Decimal('0.3')) # 0.0
- print(decimal.Decimal(1)/decimal.Decimal(7)) # 0.1428571428571428571428571429
- decimal.getcontext().prec = 2
- print(decimal.Decimal(1)/decimal.Decimal(7)) # 0.14
- with decimal.localcontext() as ctx:
- ctx.prec = 4
- print(decimal.Decimal(1)/decimal.Decimal(7)) # 0.1429
- print(decimal.Decimal(1)/decimal.Decimal(7)) # 0.14
decimal 的 localgetcontext 可以临时设置小数的精度, 结合上下文管理器
- with decimal.localcontext() as ctx:
- ctx.prec = 4
来临时使用
- import fractions
- print(fractions.Fraction(2.5)) # 小数转化为分数 5/2
- print((2.5).as_integer_ratio()) # 5,2
- spliting()
- x = set('abcde') # 有五个元素
- y = set('bdxyz')
- print(x) # {
- 'a', 'b', 'c', 'd', 'e'
- }
- print(x-y) # {
- 'a', 'c', 'e'
- }
- a = {
- 'wer'
- } # 有一个元素
- print(x | y) # {
- 'e', 'd', 'a', 'x', 'y', 'b', 'z', 'c'
- }
- print(x & y) # {
- 'b', 'd'
- }
- print(x^y) # {
- 'e', 'z', 'y', 'a', 'x', 'c'
- }
- print(x> y , x <y) # False False
- z =(x.intersection(y))
- print(z) # {
- 'd', 'b'
- }
- z.add('spam')
- print(z) # {
- 'spam', 'd', 'b'
- }
- z.update(set(('x','y')))
- print(z) # {
- 'b', 'y', 'x', 'spam', 'd'
- }
- z.remove('b')
- print(z) # {
- 'spam', 'x', 'd', 'y'
- }
- s = set([1,2,3])
- print(s.union(set([4,5]))) # {
- 1, 2, 3, 4, 5
- }
- print(s.issubset(range(-5,5))) # True
- spliting()
- s = {
- 1.23
- }
- print(s.add([1,2,3])) error
- print(s.add({
- 1:34
- })) error
- s.add((1.24))
- print(s) # {
- 1.23, 1.24
- }
- l = [1,1,2,3,4,5,5,6]
- print(list(set(l))) # [1, 2, 3, 4, 5, 6]
- a = {
- 1,2,3,4
- }
- b = {
- 2,3,5,6
- }
- print(2 in a) # True
- print(a & b) # {
- 2, 3
- }
- print(a.intersection(b)) # {
- 2, 3
- }
- print(a | b) # {
- 1, 2, 3, 4, 5, 6
- }
- print(a.union(b)) # {
- 1, 2, 3, 4, 5, 6
- }
- print(a-b) # {
- 1, 4
- }
- print(a.difference(b)) # {
- 1, 4
- }
- print(a^b) # {
- 1, 4, 5, 6
- }
- print(a.symmetric_difference(b)) # {
- 1, 4, 5, 6
- }
- spliting()
- print(type(True)) # <class 'bool'>
- print(isinstance(True,int)) # True
- print(True + 1) # 2
来源: http://www.bubuko.com/infodetail-3110506.html