Creating multiple list from loops

Question

I want to make multiple lists with my for loops, My code is:

  for port in portlist1:
    print port.getname(),port.getsize()
    for register in port.getregisters():
        j=j+1
    print j
    j=0

Output is:

I want to make list every time:

List1=[[B,10],1]
List2=[[C,15],1]
List3=[[F,30],1]

Can someone help me here?

Use list comprehensions: [ [[p.getname(),p.getsize()],len(p.getregisters())] for p in portlist1] — mtadd
– mtadd, Commented Jul 17, 2013 at 18:34

Maciej Gol · Accepted Answer · 2013-07-17 18:30:47Z

2

lists = []
for port in portlist1:
    l = [[port.getname(), port.getsize()]]
    for register in port.getregisters():
        j=j+1
    l.append(j)
    lists.append(l)
    j=0

answered Jul 17, 2013 at 18:30

Maciej Gol

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1 Comment

akaRem Over a year ago

Inline as suggested by alecxe or using generator makes code much, much faster than your variant with multiple lookup overheads like l.append. BTW, j=j+1 = lol. --> j+=1

alecxe · Accepted Answer · 2013-07-17 18:32:45Z

2

It's not clear what was the value of j before the loop, but it looks like you are using it to measure the length of port.getregisters(). Try this one-liner:

result = [[[port.getname(), port.getsize()], len(port.getregisters())] for port in portlist1]

answered Jul 17, 2013 at 18:32

alecxe

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2 Comments

mtadd Over a year ago

missing close paren on len() call

akaRem Over a year ago

@alecxe Да пожалуйста! ;)

b0bz · Accepted Answer · 2013-07-17 19:47:36Z

1

It's a bad idea to make a new list each time, you should just go with nesting each list. If the amount of ports is static, you can use vars()['listX'].. But still not really recomended. You should go with the answer given by kroolik or alecxe

But if you REALLY need someting like..:

List1=[[B,10],1]
List2=[[C,15],1]
List3=[[F,30],1]

You can use:

lname = "list"
for i,p in enumerate(portlist1):
    j = len(p.getregisters())
    vars()[lname+str(i)] = [(p.getname(),p.getsize()), j]

print list0
print list1
print list2

edited Jul 17, 2013 at 19:47

answered Jul 17, 2013 at 18:52

b0bz

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7 Comments

akaRem Over a year ago

vars()[lname+str(i)] is unpythonic

b0bz Over a year ago

@akaRem : It's not like I recommended it, I just answered his question: «Creating multiple list from loops»

akaRem Over a year ago

It really looks like you recommend it for solving this problem.. Uh.

b0bz Over a year ago

@akaRem, read it again: "But still not really recomended. You should go with the answer given by kroolik or alecxe". I answered the question, where he ASKED to have diffrent lists as output "I want to make list every time:*example given*".

akaRem Over a year ago

"I want to make list every time" -> Use yield which is fast and memory-safe.. But I'll stop pushing. ;)

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