Exercises: Computational Statistics in Python - Introduction to Python

To prepare for further exploration in data analytics, and give myself some time to absorb R, I decided to work in Python for a while. For this, I worked through Computational Statistics in Python module Introduction to Python. These are some of the code produced to solve the exercises:

 # Tutorial Answers  
 """http://people.duke.edu/~ccc14/sta-663/IntroductionToPythonSolutions.html"""    
   
 """1. Solve the FizzBuzz problem  
 “Write a program that prints the numbers from 1 to 100. But for multiples of three print “Fizz”   
 instead of the number and for the multiples of five print “Buzz”.   
 For numbers which are multiples of both three and five print “FizzBuzz”."""  
 def fizz_buzz(begin, end):  
   """Write a program that prints the numbers from 1 to 100.  
   But for multiples of three print “Fizz” instead of the number  
   and for the multiples of five print “Buzz”.  
   For numbers which are multiples of both three and five print “FizzBuzz"""  
   for i in range(begin, end):  
     if i%3 == 0 & i%5 == 0:  
       print("FizzBuzz")  
     elif i%5 == 0:  
       print("Buzz")  
     elif i%3 == 0:  
       print("Fizz")  
     else:  
       print(i)  
   
 fizz_buzz(0,100)  
   
   
 """2. Given x=3 and y=4, swap the values of x and y so that x=4 and y=3."""  
 x, y = 3, 4  
 x, y = y, x  
   
   
 """3. Write a function that calculates and returns the euclidean distance between two points u and v,   
 where u and v are both 2-tuples (x,y)(x,y). For example, if u=(3,0) and v=(0,4),   
 the function should return 55."""  
 import math  
 def euclidean(UPoint, VPoint, ShortCalc):  
   """Write a function that calculates and returns the euclidean distance   
   between two points u and v, where u and v are both 2-tuples (x,y).   
   For example, if u=(3,0) and v=(0,4) the function should return 5."""  
   try:  
     if ShortCalc == False:  
       hyp = UPoint[0]**2 + VPoint[1]**2  
       return hyp**.5  
     elif ShortCalc == True:  
       return math.hypot(UPoint[0], VPoint[1])  
   except:  
     return 0  
   
 euclidean((3,0),(0,4),True)  
   
   
 """4. Using a dictionary, write a program to calculate the number times each character occurs in the given string s.   
 Ignore differneces in capitalization - i.e ‘a’ and ‘A’ should be treated as a single key. For example,   
 we should get a count of 7 for ‘a’."""  
 import string  
 someString = """Write a function that calculates and returns the euclidean distance   
   between two points u and v, where u and v are both 2-tuples (x,y).   
   For example, if u=(3,0) and v=(0,4) the function should return 5."""  
   
 def CountCharacters(someString):  
    """Using a dictionary, write a program to calculate the number times   
    each character occurs in the given string s. Ignore differneces in   
    capitalization - i.e ‘a’ and ‘A’ should be treated as a single key.   
    For example, we should get a count of 7 for ‘a’."""  
    arr = list(someString.lower())  
    arrUnique = dict.fromkeys(set(arr), 0)  
    for item in arrUnique:  
      arrUnique[item] = arr.count(item)  
    return arrUnique  
   
 def CountCharactersAlt(someString):  
    """Using a dictionary, write a program to calculate the number times   
    each character occurs in the given string s. Ignore differneces in   
    capitalization - i.e ‘a’ and ‘A’ should be treated as a single key.   
    For example, we should get a count of 7 for ‘a’."""  
    newDict = {}  
    for item in list(someString.lower()):  
      try:  
        val = newDict.get(item)  
        newDict[item] = val + 1  
      except:  
        newDict[item] = 1  
    return newDict  
   
 def CountCharactersAlt2(someString):  
    """Using a dictionary, write a program to calculate the number times   
    each character occurs in the given string s. Ignore differneces in   
    capitalization - i.e ‘a’ and ‘A’ should be treated as a single key.   
    For example, we should get a count of 7 for ‘a’."""  
    newDict = {}  
    for item in someString.lower():  
      newDict[item] = newDict.get(item, 0) + 1  
    return newDict  
   
 CountCharacters(someString)  
 CountCharactersAlt(someString)  
 CountCharactersAlt(someString)  
   
   
 """5. Write a program that finds the percentage of sliding windows of length 5 for the sentence s that   
 contain at least one ‘a’. Ignore case, spaces and punctuation. For example, the first sliding window   
 is ‘write’ which contains 0 ‘a’s, and the second is ‘ritea’ which contains 1 ‘a’."""  
 import string  
 somestring = """Write a function that calculates and returns the euclidean distance   
   between two points u and v, where u and v are both 2-tuples (x,y).   
   For example, if u=(3,0) and v=(0,4) the function should return 5."""  
   
 def Sliding_Windows_Percentage(someString, findThis):  
    """Write a program that finds the percentage of sliding windows   
    of length 5 for the sentence s that contain at least one ‘a’.   
    Ignore case, spaces and punctuation. For example, the first   
    sliding window is ‘write’ which contains 0 ‘a’s, and the second   
    is ‘ritea’ which contains 1 ‘a’."""  
    exclude = set(string.punctuation)  
    out = ''.join(ch for ch in somestring.replace(" ","").replace("/n","") if ch not in exclude)  
    found_Counter = 0  
    for i in range(0, len(out)-4):  
      if findThis in out[i: i+4]:  
        found_Counter += 1  
    return found_Counter / (len(out)-4)  
   
 Sliding_Windows_Percentage(somestring, 'b')  
   
 """6. Find the unique numbers in the following list."""  
 numList = [36, 45, 58, 3, 74, 96, 64, 45, 31, 10, 24, 19, 33, 86, 99, 18, 63, 70, 85,  
  85, 63, 47, 56, 42, 70, 84, 88, 55, 20, 54, 8, 56, 51, 79, 81, 57, 37, 91,  
  1, 84, 84, 36, 66, 9, 89, 50, 42, 91, 50, 95, 90, 98, 39, 16, 82, 31, 92, 41,  
  45, 30, 66, 70, 34, 85, 94, 5, 3, 36, 72, 91, 84, 34, 87, 75, 53, 51, 20, 89, 51, 20]  
   
 #Soluton 1  
 list(dict.fromkeys(set(numList), 0).keys())  
   
 #Solution 2  
 list(set(numList) & set(numList))  
   
   
 """8. Create a list of the cubes of x for x in [0, 10] using  
 a for loop  
 a list comprehension  
 the map function"""  
 testListForLoop = [x for x in range(0, 11)]  
 testListComprehension = [x**3 for x in range(0, 11)]  
 testListMap = list(map(lambda x: x**3, testListForLoop))  
   
   
 """9. A Pythagorean triple is an integer solution to the Pythagorean theorem a2+b2=c2a2+b2=c2.   
 The first Pythagorean triple is (3,4,5). Find all unique Pythagorean triples for the positive   
 integers a, b and c less than 100."""  
 import math  
 def findTriples():  
   """A Pythagorean triple is an integer solution to the Pythagorean theorem a2+b2=c2.   
   The first Pythagorean triple is (3,4,5). Find all unique Pythagorean triples for the positive   
   integers a, b and c less than 100."""  
   resultList = list()  
   for leg1 in range(1, 100):  
     for leg2 in range(1, 100):  
       leg3 = math.hypot(leg1, leg2)  
       if leg3 == math.floor(leg3) & math.floor(leg3) <= 100:  
         resultList.append([leg1,leg2,int(leg3)])  
   return resultList  
   
 # The better solution  
 pythagorean_triples = [(a, b, c) for a in range(1, 100)  
                  for b in range(1, 100)  
                  for c in range(1, 100)  
                  if a**2 + b**2 == c**2]  
   
   
 """10. Fix the bug in this function that is intended to take a list of numbers   
 and return a list of normalized numbers."""  
 def f(xs):  
   """Return normalized list summing to 1."""  
   s = 0  
   for x in xs:  
     s += x  
   tempList = [(x/s)/2 for x in xs]  
   return tempList + list(reversed(tempList))  

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