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Rivier Grullon
Rivier Grullon

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Understanding 2D array (with python)

2D Array

Two dimensional array is an array within an array inside, in this type of array the position of a data element is refered by two indices , it's represents a table with row and columns of data. An example of this can be a recolect of the temperature in a week:

  • Day 1 - 11, 12, 5, 2
  • Day 2 - 15, 6, 10
  • Day 3 - 10, 8, 12, 5
  • Day 4 - 12, 15,8, 6

In ther array this can be represented like this:

T = [[11, 12, 5, 2], [15, 6,10], [10, 8, 12, 5], [12,15,8,6]]

Accesing values in a two dimensional array

How I write before for you can acces of a specific value of the array, you have to use two indices. One index referring to the parent array and other to refer the position inside the parent:

T = [[11, 12, 5, 2], [15, 6,10], [10, 8, 12, 5], [12,15,8,6]]

print(T[1][2])
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When the code above is execute the output is

10

To printe the entire 2d array we can use the for loop to iterate this:

for r in T:
    for c in r:
        print(c, end = " ")
   print()

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output:

11 12 5 2
15 6 10
10 8 12 5
12 15 8 6

Inserting values in the two dimensional array

We can insert new data at specific position by using the insert() method and specifying the index:

T.insert(2, [0,5,11,13,6])

for r in T:
    for c in r:
        print(c,end = " ")
    print()
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output:

11 12 5 2
15 6 10
0 5 11 13 6
10 8 12 5
12 15 8 6

Updating values in two dimensional array

We can edit the entire inner array or some specific element by reassigning the values using the array index:

T[2] = [ 11, 9]
T[0][3] = 7

Now the array will be:

11 12 5 7
15 6 10
11 9
12 15 8 6

Deleting the values in two dimensional array

We can also delete the entire inner array or some specific data using the index and the keyword del before:

del T[3]

The array will be:

11 12 5 2
15 6 10
10 8 12 5


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Thank you for read.

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