import math

import cmath

# Complex
for cpx in [3j, 1.5 + 1j, -2 - 2j]:

    # Polar coordinate conversion
    plr = cmath.polar(cpx)
    print 'Complex:', cpx
    print 'Polar:', plr, '(in radians)'
    print 'Amplitude:', abs(cpx)
    print 'Angle:', math.degrees(plr[1]), '(grades)'

import random
import string

# Choose a letter
print random.choice(string.ascii_uppercase)

# Choose a number from 1 to 10
print random.randrange(1, 11)

# Choose a float from 0 to 1
print random.random()

from decimal import Decimal

t = 5.
for i in range(50):
    t = t - 0.1

print 'Float:', t

t = Decimal('5.')
for i in range(50):
    t = t - Decimal('0.1')

print 'Decimal:', t

from fractions import Fraction

# Three fractions
f1 = Fraction('-2/3')
f2 = Fraction(3, 4)
f3 = Fraction('.25')
print "Fraction('-2/3') =", f1
print "Fraction('3, 4') =", f2
print "Fraction('.25') =", f3

# Sum
print f1, '+', f2, '=', f1 + f2
print f2, '+', f3, '=', f2 + f3

import sys

# Create an object of type file
temp = open('temp.txt', 'w')

# Write output
for i in range(20):
    temp.write('%03d\n' % i)

temp.close()

temp = open('temp.txt')

# Write in terminal
for x in temp:
    # writing in sys.stdout sends
    # text to standard output
    sys.stdout.write(x)

temp.close()

import sys
import os.path

fn = 'test.txt'

if not os.path.exists(fn):
    print 'Try again...'
    sys.exit()

# Numbering lines
for i, s in enumerate(open(fn)):
    print i + 1, s,

# Prints a list with all the lines from a file
print open('temp.txt').readlines()

import os.path
import glob

# Shows a list of file names
# and their respective sizes 
for arq in sorted(glob.glob('*.py')):
    print arq, os.path.getsize(arq)

import os

text = 'Test'
# creates a temporary file
temp = os.tmpfile()

# writes in the temp file
temp.write(text)

# Go back to the beginning the the file
temp.seek(0)

# Shows file content
print temp.read()

# Closes file
temp.close()

"""
Writing text in a compressed file
"""

import zipfile

text = """
**************************************
This text will be compressed and ...
... stored inside a zip file.
***************************************
"""

# Creates a new zip
zip = zipfile.ZipFile('arq.zip', 'w',
    zipfile.ZIP_DEFLATED)

# Writes a string in zip as if it were a file
zip.writestr('text.txt', text)

# closes the zip
zip.close()

"""
Reading a compressed file
"""

import zipfile

# Open the zip file for reading 
zip = zipfile.ZipFile('arq.zip')

# Gets a list of compressed files
arqs = zip.namelist()

for arq in arqs:
    # Shows the file name
    print 'File:', arq
    # get file info
    zipinfo = zip.getinfo(arq)
    print 'Original size:', zipinfo.file_size
    print 'Compressed size:', zipinfo.compress_size

    # Shows file content
    print zip.read(arq)

import csv

# Data
dt = (('temperatura', 15.0, 'C', '10:40', '2006-12-31'),
    ('peso', 42.5, 'kg', '10:45', '2006-12-31'))

# A writing routine which receives one object of type file
out = csv.writer(file('dt.csv', 'w'))

# Writing the tuples in file
out.writerows(dt)

import csv

# The reading routine receives a file object
dt = csv.reader(file('dt.csv'))

# For each record in file, prints
for reg in dt:
    print reg

import os
import sys
import platform

def uid():
    """
    uid() -> returns the current user identification
    or None if not possible to identify
    """

    # Ambient variables for each operating system
    us = {'Windows': 'USERNAME',
        'Linux': 'USER'}

    u = us.get(platform.system())
    return os.environ.get(u)

print 'User:', uid()
print 'plataform:', platform.platform()
print 'Current dir:', os.path.abspath(os.curdir)
exep, exef = os.path.split(sys.executable)
print 'Executable:', exef
print 'Executable dir:', exep

import sys
from subprocess import Popen, PIPE

# ping
cmd = 'ping -c 1 '
# No Windows
if sys.platform == 'win32':
    cmd = 'ping -n 1 '

# Local just for testing
host = '127.0.0.1'

# Comunicates with another process
# a pipe with the command stdout
py = Popen(cmd + host, stdout=PIPE)

# Shows command output
print py.stdout.read()

import time

# localtime() Returns a date and local time in the form 
# of a structure called struct_time, which is a 
# collection with the items: year, month, day, hour, minute,
# secund, day of the week, day of the year and e daylight saving time
print time.localtime()

# asctime() returns a date and hour with string, according to
# operating system configuration
print time.asctime()

# time() returns system time in seconds
ts1 = time.time()

# gmtime() converts seconds to struct_time
tt1 = time.gmtime(ts1)
print ts1, '->', tt1

# Adding an hour
tt2 = time.gmtime(ts1 + 3600.)

# mktime() converts struct_time  to seconds
ts2 = time.mktime(tt2)
print ts2, '->', tt2

# clock() returs time since the program started, in seconds
print 'The program took', time.clock(), \
    'seconds up to now...'

# Counting seconds...
for i in xrange(5):

    # sleep() waits the number of seconds specified as parameter
    time.sleep(1)
    print i + 1, 'second(s)'

import datetime

# datetime() receives as parameter:
# year, month, day, hour, minute, second and 
# returns an object of type datetime
dt = datetime.datetime(2020, 12, 31, 23, 59, 59)

# Objects date and time can be created from
# a datetime object
date = dt.date()
hour = dt.time()

# How many time to 12/31/2020
dd = dt - dt.today()

print 'Date:', date
print 'Hour:', hour
print 'How many time to 12/31/2020:', dd


import re

# Compile the regular expression using compile()
# the compiled regular expression is stored and 
# can be reused
rex = re.compile('\w+')

# Finds the occurrences according to the expression
bands = 'Yes, Genesis & Camel'
print bands, '->', rex.findall(bands)

# Identify occurrences of Björk (and their variations)
bjork = re.compile('[Bb]j[öo]rk')
for m in ('Björk', 'björk', 'Biork', 'Bjork', 'bjork'):

    # match() finds occurrences at the beginning of the string
    # to find at any part of the string, use search()
    print m, '->', bool(bjork.match(m))

# Replacing text
text = 'The next track is Stairway to Heaven'
print text, '->', re. sub('[Ss]tairway [Tt]o [Hh]eaven',
    'The Rover', text)

# Splitting text
bands = 'Tool, Porcupine Tree and NIN'
print bands, '->', re.split(',?\s+and?\s+', bands)