[Tutor] how to convert array into tuple

[Noufal Ibrahim]

bhaaluu wrote:
> Can you explain how this works? How would this be written in
> a "conventional" way?

I'm not sure if this is addressed to me but I'll reply anyway. :)

>>>> foo = [1,2,3,4,5,6]
>>>> [(foo[i],foo[i+1]) for i in range(0,len(foo),2)]

range(0,len(foo)) would create a list of consecutive numbers starting 
from the first argument (0) till (but not including) the last (len(foo))
This will run as range(0,6) and will return
[0,1,2,3,4,5]

The 2 as the third argument to range specifies the increment (common 
difference of the arithmetic progression). So if you say range(0,10,2), 
you'd get [0,2,4,6,8]. If you say range(0,10,3), you'd get [0,3,6,9] 
etc. Thus the list comprehension is written to iterate over [0,2,4]

i is used as the loop variable in the list comprehension and we return 
tuples consisting of the ith and the i+1th elements of the list.

So, it should return
[(foo[0],foo[1]),
  (foo[2],foo[3]),
  (foo[4],foo[5])
]

Which is the result. Using a for loop, you can write this as

res = []
for i in range(0,len(foo),2):
   res.append( (foo[i],foo[i+1],))

print res

I hope I'm clear


> Also, what kinds of ways might this be used?

I can't off the cuff think of anything.

Peace

-- 
~noufal