ソフトウェアエンジニアの技術ブログ：Software engineer tech blog

import turtle

def draw_star(some_turtle):
    for i in range(1, 6):
        some_turtle.forward(100)
        some_turtle.right(144)

def draw_art():
    window = turtle.Screen()
    window.bgcolor("red")
    
    brad = turtle.Turtle()
    brad.shape("arrow")
    brad.color("blue")    
    brad.speed(5)
    for i in range(1, 11):
        draw_star(brad)
        brad.right(36)

    # angie = turtle.Turtle()
    # angie.shape("arrow")
    # angie.color("blue")
    # angie.circle(100)

    # triangle = turtle.Turtle()
    # angie.shape("arrow")
    # angie.color("blue")
    
    # for x in range(0, 3):
    #    brad.forward(100)
    #    brad.right(240)

    window.exitonclick()

draw_art()

open file and read the content from the file.
python library: https://docs.python.org/2/library/functions.html#open

below code “quotes” indicate the object another word instance.

def read_text():
   quotes = open(r"C:\Users\hoge\Desktop\controller\movie_quote.txt")
   contents_of_file = quotes.read()
   print(contents_of_file)
   quotes.close()
   
read_text()

using python build-in function

def multi_func(a, b):
    return a*b

items = [1,3, 5, 7]
def reduce_value():
    value = reduce(multi_func, items)
    print(value)

reduce_value()

105
>>>

time alert program which call you tube video.

import time
import webbrowser

total_breaks = 3
break_count = 0

print("this program start on"+time.ctime())
while(break_count < total_breaks):
    time.sleep(2*60*60)
    webbrowser.open("https://www.youtube.com/watch?v=PDSkFeMVNFs")
    break_count = break_count + 1

get a file from computer and rename file name.In this case, remove the number of file name.

import os
def rename_files():
    #(1)get file names from a folder
    file_list = os.listdir(r"C:\Users\prank")
    #print(file_list)
    save_path = os.getcwd()
    print(save_path)
    os.chdir(r"C:\Users\prank")
    #(2)for each file, rename filename
    for file_name in file_list:
       os.rename(file_name, file_name.translate(None, "0123456789"))
    os.chdir(save_path)

rename_files()

def crawl_web(seed): # returns index, graph of outlinks
    tocrawl = [seed]
    crawled = []
    graph = {}  # <url>:[list of pages it links to]
    index = {} 
    while tocrawl: 
        page = tocrawl.pop()
        if page not in crawled:
            content = get_page(page)
            add_page_to_index(index, page, content)
            outlinks = get_all_links(content)
            graph[page] = outlinks
            union(tocrawl, outlinks)
            crawled.append(page)
    return index, graph

def ancestors(genealogy, person):
  if person in genealogy:
    parents = genealogy[person]
    result = parents
    for parent in parents:
      result = result + ancestors(genealogy, parent)
    return result
    
  return []

Blaise Pascal Triangle

def make_next_row(row):
  result = []
  prev = 0
  for e in row:
    result.append(e + prev)
    prev = e
  result.append(prev)
  return result

def triangle(n):
  result = []
  current = [1]
  for unused in range(0, n):
    result.append(current)
    current = make_next_row(current)
    
  return result

-base cases
fibonacci(0)=0
fibonacci(1)=1

-recursive case
fibonacci(n) = fibonacci(n-1)+fibonacci(n-2)
n > 1

A procedure, fibonacci, that takes a natural number as its input, and returns the value of that fibonacci number.

def fibonacci(n):
    if n == 0:
      return 0
    if n == 1:
      return n
    return fibonacci(n-1) + fibonacci(n-2)

fibonacci has interesting feature below
fibo(x) = fibo(x-n-1)

More faster fibonacci procedure using for loop.

def fibonacci(n):
    current = 0
    after = 1
    for i in range(0, n):
      current, after = after, current + after
    return current

mass_of_earth = 5.9722 * 10**24
mass_of_rabbit = 2

n = 1
while fibonacci(n) * mass_of_rabbit < mass_of_earth:
  n = n + 1
print n, fibonacci(n)

- Ranking web pages as popularity
popularity(p) = # of people who are friends with p
popularity(p) = Σ popularity(f), f E friends of p

def popularity(p):
score = 0
for f in friends(p):
score = score + popularity(f)
return score

factorial(n) = n*(n-1)*(n-2)*…1

factorial(n)=1
factorial(n)=n*factorial(n-1)

A procedure, factorial, that takes a natural number as its input, and returns the number of ways to arrange the input number of items.

def factorial(n):
 if n == 0:
   return 1
 else:
   return n * factorial(n-1)

Palindromes:match the first and last string, such as level.
A procedure is_palindrome, that takes as input a string, and returns a Boolean indicating if the input string is a palindrome.

def is_palindrome(s):
  if s == "":
    return True
  else:
    if s[1] == s[-1]:
        return is_palindrome(s[1:-1])
    else:
        return false

Another way, using for loop, to write palindrome procedure.

def iter_palindrome(s):
  for i in range(0, len(s)/2):
    if s[i] != s[-(i + 1)]:
      return False
  return True