How to create a list of lists in Python

Question

I have a start end, and a step, I would like to create a list like this (start= 0, end = 300, step = 100):

[[1, 100], [101, 200], [201, 300]]

The start, end, and step will vary, so I have to dynamically create the list.

Your list is inconsistent. You add 100 the first time, then 99 every other time.. — Brendan Long
– Brendan Long, Commented Nov 21, 2012 at 17:49
Sorry guys, the start is 1, and the step in this sample is 99. It will vary. — dtch
– dtch, Commented Nov 21, 2012 at 17:51
@user1842734: Please edit your question to show the true input and output. — kennytm
– kennytm, Commented Nov 21, 2012 at 17:55

applicative_functor · Accepted Answer · 2012-11-21 17:54:28Z

4

>>> start = 0
>>> end = 300
>>> step = 100
>>> [[1 + x, step + x] for x in range(start, end, step)]
[[1, 100], [101, 200], [201, 300]]

answered Nov 21, 2012 at 17:54

applicative_functor

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dtch Over a year ago

black_dragon this is exactly what I need. Thank you!

Rohit Jain · Accepted Answer · 2012-11-21 17:53:01Z

1

You just need a simple while loop: -

start = 0
end = 300
step = 100

my_list = []

while start < end:   # Loop until you reach the end
    my_list.append([start + 1, start + step]) 
    start += step    # Increment start by step value to consider next group

print my_list

OUTPUT : -

[[1, 100], [101, 200], [201, 300]]

The same thing can be achieved by range or xrange function, in a list comprehension.

answered Nov 21, 2012 at 17:53

Rohit Jain

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dtch Over a year ago

Thank you all! You have been awesome! :-)

Brendan Long · Accepted Answer · 2012-11-21 17:56:59Z

1

You can create two ranges and zip them together:

def do_your_thing(start, end, step):
    return zip(range(start, end - step + 2, step),
               range(start + step - 1, end + 1, step))

answered Nov 21, 2012 at 17:56

Brendan Long

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