CODEWITHSUNDEEP
pythonlistrange
y3di
y3di

Reputation: 673

issues with python range()

I have the following code: 

def steps(low, hi, n):
rn = range(n)
newrn = rn
print rn #print 1
for x in rn[:]:
    print x
    newrn[x] = float(x)/n

diff = hi - low

print newrn 
print rn #print 2
for y in rn[:]:
    print y
    rn.insert(y, (newrn[y] * diff) + low)

return rn

for some reason, my first print of rn returns [0, 1, 2] but my second print returns [0, .333, .666]. Why is rn changing? I only change newrn, but rn is getting changed as well. This is making me get a 'list indices must be integer not float' error when it tries to run the rn.insert line.

any help?

Upvotes: 0

Views: 237

Answers (2)

Staven
Staven

Reputation: 3165

This is how variables work in python. In there:

newrn = rn

You're assigning a reference, not a value (which is good sometimes, since you don't copy all the values to a new list). If you want a new, separate list with the same values, do this:

newrn = list(rn)

Upvotes: 3

cheeken
cheeken

Reputation: 34655

The problem is when you made this assignment: newrn = rn. Now both newrn and rn point to the same list, so when you modify one, you modify both.

Use newrn = rn[:] instead.

Upvotes: 5

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