Network (Graph)

A Network is a collection of connected nodes

What is a Network (Graph) ๐ŸŽ†

A Network is a collection of connected nodes. nodes = elements

Courtesy of NASA taken from ISS

Earth ๐ŸŒŽ ๐ŸŒ ๐ŸŒ

Viewing earth from the international space station, there is clusters of light in a sea of darkness. These pockets of light are highly connected Networks of people and things people make.

Social Network ๐ŸŒ

A Social Network is groups of people connected together.

Each line is equal to a friendship

Kyle's Facebook Friend Profile: ๐ŸŒ

  • Family Network:

    • โค๏ธWife, Kids, parents, grandparents, cousins, aunts, uncles, inlawsโค๏ธ

  • Friends Network:

    • childhood friends๐Ÿผ, work friends๐Ÿ‘ทโ€โ™€๏ธ, hobbie friends๐Ÿ€๐ŸŽฎ

  • Dank Meme & Programming Network: ๐Ÿ’ฏ

    • ๐Ÿ˜œweirdos๐Ÿคชmore weirdos๐Ÿคฅ

I'm personally connected to all these people above in a Network. All of the people im connected to are also connected to their own people. and all of those people are... etc, etc, etc...

I Need a Map, A Map of the Internet! ๐Ÿง 

Networks are used to represent more complicated relationships and normally used when other data structures simply will not work.

Partial map of the Internet from opte.org

Types of Networks ๐ŸŒฌ๏ธ ๐ŸŒช๏ธ

Directed Networks: Connections between nodes flow in a specific direction

  • Water always flows in one direction from a higher point to a lower point

    • ๐Ÿž๏ธ Water Tower -> Homes -> Sewer ๐Ÿž๏ธ

  • Twitters following/follower system

    • I follow the @PresidentOfTheUnitedStates ๐Ÿšถ

    • The President Of The United States does Not follow me ๐Ÿšซ

Undirected Networks: Connections between nodes flow in both directions

  • Facebooks friend system

    • I send a friend request to uncle Jim Bob and he accepts ๐Ÿ‘ฏโ€โ™‚๏ธ

Linked List vs Tree vs Network๐ŸŽ ๐ŸŒฒ ๐ŸŒŽ

Linked List and Trees can be represented as simple Networks. The following example explains the differences between the 3 as different types of networks.

Example:

  • 7 Nodes = A, B, C, D, E, F, G โœด๏ธ โœด๏ธ โœด๏ธ โœด๏ธ โœด๏ธ โœด๏ธ โœด๏ธ โœด๏ธ

Linked Lists: a simple directed network where each node flows to the next node. ๐Ÿ‘‰

  • (start) A -> B -> C -> D -> E -> F -> G -> END

Trees: are a directed network where the starting node flows down to multiple nodes ๐Ÿ‘ˆ๐Ÿ‘‰

  •            (start)
                  A 
                  '
          -------------------
         '                   '
         B                   C
         '                   '
     -----------         -----------
    '           '       '           '
    D           E       F           G

Networks: can be used to diagram highly connected systems๐Ÿ‘ˆ๐Ÿ‘‰๐Ÿ‘†๐Ÿ‘‡๐Ÿค™

  • - = 2-way connection
    ' = 2-way connection
    x = 4-way connection
    No starting point 
    No ending point
  • A  -  B  -  C
    '  x  '  x  '
    D  -  E  -  F
    '  x  '  x  '
    ----- G -----

The key takeaway is all systems have the same number of Nodes but a different number of Connections. The Connections are what make the data structure a linked list, tree or network.

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