Python loop through list starting at index

Question

I am looking for a more pythonic way to loop though a list starting an an index then return the values contained in sub-lists eg:

values = [[1,2], [2], [1,3,4]]
n=1
for i, item in enumerate(values[n:]):
    i += n
    if i < len(values):
        for sub_value in values[i]:
            print("index: "+str(i)+ " list: "+str(item)+ " sub value: "+str(sub_value))

The code works as intended but is pretty ugly, any ideas to simplify it?

Answer 1

I'm going to take a swing here and guess that you are trying to make a simple python function that loops through a list and prints out every element in the sublists. Here is the easiest way to do it:

def get_sublists(start=0):
    values = [[1,2], [2], [1,3,4]] 
    index = start 
    item = 0
    for value in values[index:]: 
        for sub_value in value: 
            print("Item: %s // Index: %s // List: %s // Sub Value: %s" % (item, index, values[index], sub_value)) 
            item += 1
        index += 1

get_sublists(1)

This will print out the following:

Item: 0 // Index: 1 // List: [2] // Sub Value: 2                                                                                                                                                                                                       
Item: 1 // Index: 2 // List: [1, 3, 4] // Sub Value: 1                                                                                                                                                                                                 
Item: 2 // Index: 2 // List: [1, 3, 4] // Sub Value: 3                                                                                                                                                                                                 
Item: 3 // Index: 2 // List: [1, 3, 4] // Sub Value: 4

I am not 100% sure about the question because it is a bit ambigous, so let me know if you have any further modifications.

Answer 2

I'm not sure I completely understand what you are trying to achieve.If you want to print a flat list of the items from index 1 you could do this:

[item for sublist in values[1:] for item in sublist]

which produces:

[2, 1, 3, 4]