# 3.1 Numbers, Dates, and Times

print(round(1.23, 1))

print(round(1.27, 1))

print(round(-1.23, 1))

print(round(-1.27, 1))

print(round(1.25361, 3))

print(round(1.25, 1))

print(round(1.37, 1))

print(round(1.5))

print(round(2.5))

a = 1627731

print(round(a, -1)) # 1627730

print(round(a, -2)) # 1627700

print(round(a, -3)) # 1628000

x = 1.23456

print(format(x, '0.2f'))

print(format(x, '0.3f'))

print('value is {:0.3f}'.format(x))

a = 2.1

b = 4.2

c = a + b

print(c)

c = round(c, 2) # "Fix" result (???)

print(c)

# 3.2 Performing Accurte Decimal Calculations

a = 4.2

b = 2.1

print(a + b)

print ((a + b) == 6.3) # False : 부동소수점 계산의 함정

# Avoid such errors if you write your code using float instances.

from decimal import Decimal

a = Decimal('4.2')

b = Decimal('2.1')

print(a+b)

print((a+b) == Decimal('6.3'))

from decimal import localcontext

a = Decimal('1.3')

b = Decimal('1.7')

print('a/b = ', a/b)

with localcontext() as ctx:

ctx.prec = 3

print('a/b = ', a/b)

with localcontext() as ctx:

ctx.prec = 50

print('a/b= ', a/b)

nums = [1.23e+18, 1, -1.23e+18] # Notice how 1 disappears

print('sum(nums)= ', sum(nums))

import math

print('math.fsum(nums)= ', math.fsum(nums))

# 3.3 Formatting Numbers for Output

x = 1234.56789

print(format(x, '0.2f'))

print(format(x, '>10.1f'))

print(format(x, '<10.1f'))

print(format(x, '^10.1f'))

print(format(x, '0,.1f')) # Inclusion of thousands separator

print(format(x, 'e')) # 지수 표현, Used for exponential specifier

print(format(x, '0.2E')) # 지수 표현, Used for exponential specifier

# General form of the width and precision : '[<>^]?width[,]?(.digits)?'

print('The value is {:0,.2f}'.format(x))

print('The value is {}'.format(x,'0,.2f')) # different result

x = 1234.56789

print(format(x, '0.1f'))

print(format(-x, '0.1f'))

# translate()

swap_separators = { ord('.'):',', ord(','):'.' }

print(format(x, ',').translate(swap_separators))

# 3.4 Working with Binary, Octal, and Hexadecimal Integers

# bin(), oct(), hex()

x = 1234

print(bin(x))

print(oct(x))

print(hex(x))

print(format(x, 'b')) # if you don't want the 0b, 0o, 0x prefixes to appear.

print(format(x, 'o'))

print(format(x, 'x'))

x = -1234

print(format(x, 'b'))

print(format(x, 'x'))

x = -1234

print(format(2**32+x, 'b'))

print(format(2**32+x, 'x'))

print(int('4d2', 16)) # 16진수를 10진수로

print(int('10011010010', 2)) # 2진수를 10진수로

# import os

# os.chmod('script.py', 0755) # Error Occured : invalid token

# os.chmod('script.py', 0o755) # It's OK

# 3.5 Packing and Unpacking Large Intgers from Bytes

data = b'\x00\x124V\x00x\x90\xab\x00\xcd\xef\x01\x00#\x004'

print(len(data))

print(int.from_bytes(data, 'little'))

print(int.from_bytes(data, 'big'))

x = 94522842520747284487117727783387188

print(x.to_bytes(16, 'big'))

print(x.to_bytes(16, 'little'))

# TODO : I can't understood

data = b'\x00\x124V\x00x\x90\xab\x00\xcd\xef\x01\x00#\x004'

import struct

hi, lo = struct.unpack('>QQ', data)

print((hi << 64) + lo)

x = 0x01020304

print(x.to_bytes(4, 'big')) # Big Edian

print(x.to_bytes(4, 'little')) # Little Edian

x = 523 ** 23

print(x)

try:

x.to_bytes(16, 'little')

except OverflowError as e:

print("Error Occured: ", e)

print(x.bit_length())

nbytes, rem = divmod(x.bit_length(), 8)

if rem:

nbytes += 1

print(x.to_bytes(nbytes, 'little'))

# 3.6 Performing Complex-Valued Math

# complex(real, imag)

a = complex(2, 4) # 2 + 4j : 복소수

b = 3 - 5j

print('a.real= ', a.real, 'a.imag= ', a.imag)

print('a.conjugate()= ', a.conjugate())

print('a+b= ', a+b)

print('a*b= ', a*b)

print('a/b= ', a/b)

print('abs(a)= ', abs(a))

import cmath

print(cmath.sin(a))

print(cmath.cos(a))

print(cmath.exp(a))

import numpy as np

a = np.array([2+3j, 4+5j, 6-7j, 8+9j])

print(a)

print(a+2)

print(np.sin(a))

import math

try:

math.sqrt(-1)

except ValueError as e:

print('Error Occured: ', e)

import cmath

print(cmath.sqrt(-1))

# 3.7 Working with Infinity and NaNs

a = float('inf')

b = float('-inf')

c = float('nan')

print(a, b, c)

# math.isinf(), math.isnan()

print(math.isinf(a))

print(math.isinf(b))

print(math.isnan(c))

a = float('inf')

print(a+45)

print(a*10)

print(10/a)

a = float('inf')

print(a/a)

b = float('-inf')

print(a+b)

c = float('nan')

print(c+23)

print(c/2)

print(c*2)

print(math.sqrt(c))

c = float('nan')

d = float('nan')

print(c==d)

print(c is d)

# 3.8 Calculating with Fractions(분수)

# fractions module

from fractions import Fraction

a = Fraction(5, 4)

b = Fraction(7, 16)

print(a+b) # 5/4 + 7/16

print(a*b) # 5/4 * 7/16

c = a * b # Getting numerator(분자)/denominator(분모)

print(c.numerator)

print(c.denominator)

print(float(c)) # Converting to a float

print(c.limit_denominator(8)) # Limiting the denominator of a value

x = 3.75

y = Fraction(*x.as_integer_ratio())

print(y)

# 3.9 Calculating with Large Numerical Arrays

x = [1, 2, 3, 4]

y = [5, 6, 7, 8]

print(x*2) # List의 곱은 문자열처럼 동작

try:

print(x+10)

except TypeError as e:

print('Error Occured: ', e)

print(x+y) # 문자열 처럼 동작: 리스트의 item이 뒤에 붙음.

import numpy as np

ax = np.array([1, 2, 3, 4])

ay = np.array([5, 6, 7, 8])

print(ax*2)

print(ax+10)

print(ax+ay)

print(ax*ay)

def f(x):

return 3*x**2 - 2*x + 7

print(f(ax))

print(np.sqrt(ax))

print(np.cos(ax))

grid = np.zeros(shape=(10000,10000), dtype=float)

print(grid)

grid += 10

print(grid)

print(np.sin(grid))

a = np.array([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]])

print(a)

print(a[1])

print(a[:,1])

print(a[1:3, 1:3])

print(a[1:3, 1:3]+10)

print(a)

a = np.array([[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12]])

print(a+[100, 101, 102, 103])

print('')

print(a)

print(np.where(a<10, a, 10))

# 3.10 Performing Matrix(행렬) and Linear Algebra(선형대수학) Calculations

import numpy as np

m = np.array([[1, -2, 3], [0, 4, 5], [7, 8, -9]])

print(m)

print(m.T) # Transpose

#print(m.I) # Inverse Error Occured

v = np.array([[2], [3], [4]])

print(m)

print(v)

print(m*v) # 단순 multiply

print(m@v) # Dot Product

import numpy.linalg

print(numpy.linalg.det(m)) # Determinant

print(numpy.linalg.eigvals(m)) # Eigenvalues(고윳값, 고유치)

print(m)

print(v)

x = numpy.linalg.solve(m, v)

print(x)

print(m@x)

# 3.11 Picking Things at Random

import random

values = [1, 2, 3, 4, 5, 6]

print(random.choice(values))

# random.sample() : To take a sampling of N items

print(random.sample(values, 2))

print(random.sample(values, 2))

print(random.sample(values, 3))

print(random.sample(values, 3))

# random.shuffle()

print(values)

random.shuffle(values)

print(values)

random.shuffle(values)

print(values)

# randint()

print(random.randint(0, 10)) # 0 ~ 10 random number

print(random.randint(0, 10))

# random.random(): range 0 ~ 1, uniform floating-point values

print(random.random())

print(random.random())

print(random.random())

# random.getrandbits(): To get N random-bits expressed as an integer,

print(random.getrandbits(200))

# random module computs randdom number using the Mersenne Twister algorithm.

# You can alter the initial seed by using the random.seed()

random.seed() # Seed based on system time or os.urandom()

random.seed(12345) # Seed based on integer given

random.seed(b'bytedata') # Seed based on byte data

# random.uniform(), random.gauss(), ssl_RAND_bytes()

# 3.12 Converting Days to Seconds, and Other Basic Time Conversions

from datetime import timedelta

a = timedelta(days=2, hours=6)

b = timedelta(hours=4.5)

c = a + b

print(c)

print(c.days)

print(c.seconds)

print(c.seconds/3600)

print(c.total_seconds()/3600)

from datetime import datetime

a = datetime(2012, 9, 23)

print(a + timedelta(days=10))

b = datetime(2012, 12, 21)

d = b - a

print(d)

print(d.days)

now = datetime.today()

print(now)

print(now + timedelta(minutes=10))

a = datetime(2012, 3, 1)

b = datetime(2012, 2, 28) # 2012.2.29 있음

print((a-b).days)

c = datetime(2013, 3, 1)

d = datetime(2013, 2, 28) # 2013.2.29 없음

print((c-d).days)

a = datetime(2012, 9, 23)

try:

print(a + timedelta(months=1))

except TypeError as e:

print(e)

from dateutil.relativedelta import relativedelta

a = datetime(2012, 9, 23)

print(a)

print(a+relativedelta(months=+1))

print(a + relativedelta(months=+4))

# Time between two dates

a = datetime(2012, 9, 23)

b = datetime(2012, 12, 21)

d = b -a

print(d)

d = relativedelta(b, a)

print(d, d.months, d.days)

# 3.13 Determining Last Friday's Date

from datetime import datetime, timedelta

weekdays = ['Monday', 'Tuesday', 'Wednesday', 'Thursday',

'Friday', 'Saturday', 'Sunday']

def get_previous_byday(dayname, start_date=None):

return target_date

print(datetime.today())

print(get_previous_byday('Sunday'))

print(get_previous_byday('Sunday', datetime(2012, 12, 21)))

from datetime import datetime

from dateutil.relativedelta import relativedelta

from dateutil.rrule import *

d = datetime.now()

k = datetime.today()

print(d)

print(k)

print(d + relativedelta(weekday=FR)) # Next Friday

print(d + relativedelta(weekday=FR(-1))) # Last Friday

# 3.14 Finding the Date Range for the Current Month

from datetime import datetime, date, timedelta

import calendar

def get_month_range(start_date=None):

return (start_date, end_date)

a_day = timedelta(days=1)

input_date = date(2019, 3, 20)

first_day, last_day = get_month_range(input_date)

while first_day < last_day:

print(first_day)

first_day += a_day

def date_range(start, stop, step):

while start < stop:

yield start

start += step

for d in date_range(datetime(2012, 9, 1), datetime(2012,10,1), timedelta(hours=12)):

print(d)

def date_range(start, stop, step):

while start < (stop + timedelta(days=1)):

yield start

start += step

for d in date_range(date(2012, 9, 1), date(2012,9,30), timedelta(days=1)):

print(d)

# 3.15 Converting Strings into Datetimes

# datetime.strptime()

# datetime.strftime()

from datetime import datetime

text = '2020-03-08'

y = datetime.strptime(text, '%Y-%m-%d')

z = datetime.now()

x = datetime.today()

diff = z - y

print(diff)

diff1= x - y

print(diff1)

print(z)

nice_z = datetime.strftime(z, '%A %B %d %Y')

print(nice_z)

# This function runs over seven times faster than datetime.strptime().

from datetime import datetime

def parse_ymd(s):

year_s, mon_s, day_s = s.split('-')

return datetime(int(year_s), int(mon_s), int(day_s))

print(parse_ymd('2020-03-20'))

# 3.16 Manipulating Dates Involving Time Zones

# You had a conference call scheduled for December 21, 2012, at 9:30 a.m in Chicago.

# 다른 곳에 있는 참여자들의 local time ?

# pytz module

from datetime import datetime

from pytz import timezone

d = datetime(2012, 12, 21, 9, 30, 0)

print(d)

central = timezone('US/Central') # Localize the date for Chicago

loc_d = central.localize(d)

print(loc_d)

bang_d = loc_d.astimezone(timezone('Asia/Kolkata'))

print(bang_d)

# Consider Daylight saving time

d = datetime(2013, 3, 10, 1, 45)

loc_d = central.localize(d)

print(loc_d)

later = loc_d + timedelta(minutes=30)

print(later) # Wrong Result

from datetime import timedelta

later = central.normalize(loc_d + timedelta(minutes=30))

print(later)

#print(loc_d)

#utc_d = loc_d.astimezone(pytz.utc)

#print(utc_d)