CODEWITHSUNDEEP
pythonlistpython-2.7
DBB
DBB

Reputation: 41

How to traverse a 2D List in python

I have the following list:

grid = [[2, 6, 8, 6, 9], [2, 5, 5, 5, 0], [1, 3, 8, 8, 7], [3, 2, 0, 6, 9], [2, 1, 4,5,8], [5, 6, 7, 4, 7]]

I used the fowling loop for traversing each element ->

for i in xrange(len(grid[i])):
    for j in xrange(len(grid[j])):
        print grid[i][j]
    print "\n"

But it doesn't show the last row i.e [5,6,7,4,7]

So, which is the proper way to travers a 2D List in python?

Upvotes: 4

Views: 36571

Answers (6)

Parakh Jain
Parakh Jain

Reputation: 1

If the number of columns are same in all the inner lists this should like==

li = [[1,2,3,4],[5,6,7,8],[9,10,11,12]]
for i in range(len(li)):
    for j in range(len(li)):
        print(li[i][j])
    print()

And if you don't know no. of columns and in any situation, this would be helpful ==

for i in li:
for j in i:
    print(j,end = " ")
print()

You can also use the following if rows and columns are different or the same:

li=[[1,2,3,4],[5,6,7],[8,9]]
for i in range(len(li)):
    for j in range(len(li[i])):
        print(li[i][j],end = " ")
   print()

Upvotes: 0

Bikash
Bikash

Reputation: 162

Why not use while loop for traversing the 2D list

grid = [[2, 6, 8, 6, 9], [2, 5, 5, 5, 0], [1, 3, 8, 8, 7], [3, 2, 0, 6, 9], [2, 1, 4,5,8], [5, 6, 7, 4, 7]]
i = 0
while i < len(grid):
    j = 0
    while j < len(grid[0]):
        print (grid[i][j], end=' ')
        j += 1
    print() #new line
    i += 1

Upvotes: 0

Soundar
Soundar

Reputation: 171

Try following instead. You can do necessary operation instead of "print grid[i][j]"

for i in range(len(grid)):
    for j in range(len(grid[i])):
        print grid[i][j]
    print '---'

Upvotes: 2

thefourtheye
thefourtheye

Reputation: 239473

The proper way to traverse a 2-D list is 

for row in grid:
    for item in row:
        print item,
    print

The for loop in Python, will pick each items on every iteration. So, from grid 2-D list, on every iteration, 1-D lists are picked. And in the inner loop, individual elements in the 1-D lists are picked.

If you are using Python 3.x, please use the print as a function, not as a statement, like this

for row in grid:
    for item in row:
        print(item, end = " ")
    print()

Output

2 6 8 6 9
2 5 5 5 0
1 3 8 8 7
3 2 0 6 9
2 1 4 5 8
5 6 7 4 7

But, in case, if you want to change the element at a particular index, then you can do

for row_index, row in enumerate(grid):
    for col_index, item in enumerate(row):
        gird[row_index][col_index] = 1     # Whatever needs to be assigned.

Upvotes: 20

Soundar
Soundar

Reputation: 171

Try following...

for i in grid:
    for j in i:
        print j
    print '----'

Upvotes: 0

FlogFR
FlogFR

Reputation: 779

Why not:

for i in grid:
    for j in i:
        print("{}".format(j))
    print("\n")

Upvotes: 0

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