Python Dictionaries

 A dictionary in python can contain name value pairs. Like

thisdict = {

    "name" : "Shiva",

    "gender" : True,

    "age" : 45,

}

where thisdict contains name, gender and age of string, boolean and int data type.

On purpose I have created another dict with a JSON as a value of a name-value pair.

thisdict = {

    "name" : "Shiva",

    "gender" : True,

    "age" : 45,

    "assets-json" : {

        "net-worth": 1000000,

        "house-type": "flat",

        "address": ["J P Nagar 5th Ph",

                    "Bangalore",

                    "560034"]

    }

}

I have made use of this dictionary structure in a program which

a. finds the length of the dictionary

b. prints the name, gender and age

c. prints the net-worth of the individual in the dictionary object.

thisdict = {

    "name" : "Shiva",

    "gender" : True,

    "age" : 45,

    "assets-json" : {

        "net-worth": 1000000,

        "house-type": "flat",

        "address": ["J P Nagar 5th Ph",

                    "Bangalore",

                    "560034"]

    }

}

thatdict = {

    "name" : "Harish",

    "gender" : True,

    "age" : 54,

    "assets-json" : {

        "net-worth": 10000000,

        "house-type": "Individual House",

        "address": ["Jayanagar",

                    "Bangalore",

                    "560045"]

    }

}

def length_of_dict(dict_param):

    return len(dict_param)

def display_dict(dict_param):

    print("this dict is of %s" % dict_param["name"])

    gender = "male" if dict_param["gender"] == True else "female"

    print("Age = %s \nGender= %s" %(dict_param["age"], gender))

    print("Net Worth:%s" % dict_param["assets-json"]["net-worth"])

if __name__=="__main__":

    print("Length of thatdict:",length_of_dict(thatdict))

    print("Length of thisdict:",length_of_dict(thisdict))

    display_dict(thatdict)

    display_dict(thisdict)

Output of the program:

Length of thatdict: 4

Length of thisdict: 4

this dict is of Harish

Age = 54

Gender= male

Net Worth:10000000

this dict is of Shiva

Age = 45

Gender= male

Net Worth:1000000

Python Lists

 In Python, a list is a built-in dynamic sized array (automatically grows and shrinks). We can store all types of items (including another list) in a list. A list may contain mixed type of items, this is possible because a list mainly stores references at contiguous locations and actual items maybe stored at different locations.

• List can contain duplicate items.
• List in Python are Mutable. Hence, we can modify, replace or delete the items.
• List are ordered. It maintain the order of elements based on how they are added.
• Accessing items in List can be done directly using their position (index), starting from 0.

nested lists in python : matrix = [

    [1, 2, 3],

    [4, 5, 6],

    [7, 8, 9]

]

# Access element at row 2, column 3

print(matrix[1][2])

Another program to find pair of numbers in a sorted array that sum to a value(target):

def pair_sum_sorted_all_pairs(arr, target):

  """

  Finds all pairs in a sorted array that sum to a given target.

  Args:

    arr: A sorted array of integers.

    target: The target sum.

  Returns:

    A list of tuples representing the pairs.

  """

  result = []

  left, right = 0, len(arr) - 1

  while left < right:

    current_sum = arr[left] + arr[right]

    if current_sum == target:

      result.append((arr[left], arr[right]))

      left += 1

      right -= 1

    elif current_sum < target:

      left += 1

    else:

      right -= 1

  return result

if __name__=="__main__":

    arr = [1, 2, 3, 4, 5, 6, 7]

    target = 8

    print(pair_sum_sorted_all_pairs(arr, target))

When we run this program here we get following output:

C:\Users\kamat>python untitled123.py

[(1, 7), (2, 6), (3, 5)]