How to specify each index number - Python

Question

I'm writing this program that is supposed to convert binary to hex. I have to use the for loop. The part I need is how do I get the program to get the integer and its index number.

my code so far

q = raw_input('asdf ')
p = list(q)
t = [int(x) for x in p]
for i in t:
    if i == 1:
    w=i*(2**(3-t[x]))
    print w

the t[x] part is supposed to be the index number. So what is happening is if its a one then it will multiply by 2^3-(its index number)

How do I refer to the index number?

And how do I get it to sum all the values it gets

If this is homework please tag it as such, otherwise there's absoluely no reason to code this yourself — Assaf Lavie
– Assaf Lavie, Commented Aug 18, 2011 at 16:16

Cédric Julien · Accepted Answer · 2011-08-18 17:22:21Z

4

You can use the enumerate function.

for rank, item in enumerate(my_list):
   # here you have the index of the item (rank)
   # and the item ( the same as my_list[rank] )

for your example you can do something like this :

 inital_binary = raw_input("polop")
 for rank, letter in enumerate(inital_binary):
    print int(letter) * 2**(len(inital_binary) - (rank+1))

that will give for an input of 1100 :

edited Aug 18, 2011 at 17:22

answered Aug 18, 2011 at 16:17

Cédric Julien

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7 Comments

jimbob Over a year ago

so instead of t[x] i put rank

Cédric Julien Over a year ago

@tyim : yes, it sounds like this

jimbob Over a year ago

i need it so that when i grabs the i it also knows what index number the i is so that it plug into the formula right each time

jimbob Over a year ago

if i use your code i gives me eight different numbers even though i only put in 4 numbers

Cédric Julien Over a year ago

@tyim : maybe i didn't understand exactly what you want -_- could you give an example of what you want to achieve (input and expected result)

|

andronikus · Accepted Answer · 2011-08-18 20:31:48Z

0

Try this:

for ind in range(len(t)):
  i = t[ind]
  ...

Then i is the variable you had before, and ind is the loop number.

For the sum, do:

result = 0

before the loop, and

  result += w

inside the loop.

answered Aug 18, 2011 at 20:31

andronikus

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