Best way to delimit a list?

[dannywebster]

Hi - I have a list returned from popen/readlines, and am wondering how
to go about iterating over each item which was returned (rather than
currently having the whole lot returned).

so far:

returns ['host1 host2 host3 ... hostN\n]'

i'd like to be in a position to iterate through these, grabbing each
host. I have played with transmuting to a str, and using split, and
this works, but I get the subscript brackets from the list output as
expected, as the list output is now a string literal, and this is not
what I want - and I think it's a bit long-winded to do a search 'n
replace on it - hence why I ask in the subject what's the best way.
["['host1","host2", ... ,"hostN\n']"]


Any help is highly appreciated

ta

dan.

 

[castironpi]

Hi - I have a list returned from popen/readlines, and am wondering how
to go about iterating over each item which was returned (rather than
currently having the whole lot returned).

so far:

returns ['host1 host2 host3 ... hostN\n]'

i'd like to be in a position to iterate through these, grabbing each
host.  I have played with transmuting to a str, and using split, and
this works, but I get the subscript brackets from the list output as
expected, as the list output is now a string literal, and this is not
what I want - and I think it's a bit long-winded to do a search 'n
replace on it - hence why I ask in the subject what's the best way.

["['host1","host2", ... ,"hostN\n']"]

Any help is highly appreciated

ta

dan.

Bring up the Google Ring. Where you only wiggle fingers, it might pay
to get jobs at home. All we up here would have to do would be
schedule something. Make a decision is easy in talking. I think it
would be easy to centralize the time the world's at and redistribute
money. If all we'd do is normal life, this constrained, open markets
would be easy to set up. It's just illegal to talk about pricing in
2004 Microecon. classes.

 

[dannywebster]

Hi - I have a list returned from popen/readlines, and am wondering how
to go about iterating over each item which was returned (rather than
currently having the whole lot returned).

so far:

returns ['host1 host2 host3 ... hostN\n]'

i'd like to be in a position to iterate through these, grabbing each
host. I have played with transmuting to a str, and using split, and
this works, but I get the subscript brackets from the list output as
expected, as the list output is now a string literal, and this is not
what I want - and I think it's a bit long-winded to do a search 'n
replace on it - hence why I ask in the subject what's the best way.

["['host1","host2", ... ,"hostN\n']"]

Any help is highly appreciated

ta

dan.

I did indeed mean "os.popen", no "os.open"

 

[Gabriel Genellina]

Hi - I have a list returned from popen/readlines, and am wondering how
to go about iterating over each item which was returned (rather than
currently having the whole lot returned).

so far:

returns ['host1 host2 host3 ... hostN\n]'

You meant readlines(), I presume. A file acts as its own iterator:

f=os.open("./get_hostnames")
try:
for line in f:
# do something with line
finally:
f.close()

 

[castironpi]

Hi - I have a list returned from popen/readlines, and am wondering how
to go about iterating over each item which was returned (rather than
currently having the whole lot returned).

so far:
returns ['host1 host2 host3 ... hostN\n]'

i'd like to be in a position to iterate through these, grabbing each
host.  I have played with transmuting to a str, and using split, and
this works, but I get the subscript brackets from the list output as
expected, as the list output is now a string literal, and this is not
what I want - and I think it's a bit long-winded to do a search 'n
replace on it - hence why I ask in the subject what's the best way.
["['host1","host2", ... ,"hostN\n']"]

Any help is highly appreciated

dan.

I did indeed mean "os.popen", no "os.open"- Hide quoted text -

- Show quoted text -

I do indeed write a pretty fine real-time, low-bandwidth, game. It is
like real-time chess, and seen the movie, Tron. Can't the P2Ps zip up
in an hour?

 

[dannywebster]

You meant readlines(), I presume. A file acts as its own iterator:

f=os.open("./get_hostnames")
try:
for line in f:
# do something with line
finally:
f.close()

Hi - thank you for your reply.

I meant:

f=os.popen("./get_hostnames").readlines()

So f is a list, rather than a file object, of which os.open would have
returned (my initial typo redirected the missive of this post, sorry!)

cheers

 

[Gabriel Genellina]

On May 13, 11:28 am, (e-mail address removed) wrote:

I did indeed mean "os.popen", no "os.open"

Ouch, replace open with popen an my example is valid (but to get the
meaning I intended to write, replace os.open with open...)

 

[castironpi]

Ouch, replace open with popen an my example is valid (but to get the  
meaning I intended to write, replace os.open with open...)

Writing's fine, but don't the musicals suck?

 

[castironpi]

Ouch, replace open with popen an my example is valid (but to get the  
meaning I intended to write, replace os.open with open...)

Yes: fine! But, all we do is start a Tron ring, play Tron on
laptops. You have micro-divide currency, you can probably make
musicals -too-; and I don't have enough to say to get this...

BE TALKING!

 

[Wolfgang Grafen]

Hi - I have a list returned from popen/readlines, and am wondering how
to go about iterating over each item which was returned (rather than
currently having the whole lot returned).

so far:

returns ['host1 host2 host3 ... hostN\n]'

i'd like to be in a position to iterate through these, grabbing each
host. I have played with transmuting to a str, and using split, and
this works, but I get the subscript brackets from the list output as
expected, as the list output is now a string literal, and this is not
what I want - and I think it's a bit long-winded to do a search 'n
replace on it - hence why I ask in the subject what's the best way.
["['host1","host2", ... ,"hostN\n']"]


Any help is highly appreciated

untested:
f=" ".join(f)
f.split()

Best regards

Wolfgang

 

[J. Clifford Dyer]

Hi - I have a list returned from popen/readlines, and am wondering how
to go about iterating over each item which was returned (rather than
currently having the whole lot returned).

so far:

returns ['host1 host2 host3 ... hostN\n]'

i'd like to be in a position to iterate through these, grabbing each
host. I have played with transmuting to a str, and using split, and
this works, but I get the subscript brackets from the list output as
expected, as the list output is now a string literal, and this is not
what I want - and I think it's a bit long-winded to do a search 'n
replace on it - hence why I ask in the subject what's the best way.
["['host1","host2", ... ,"hostN\n']"]

Instead of casting to a string, each element of your list is already a
string, so use that instead:

f = open("get_hostnames")
hosts =[]

# gets each string one at a time.
for line in f:
# get rid of the pesky \n at the end
line = line.strip()
# separate the hostnames into a list
hosts += line.split(' ')

 

[Giuseppe Ottaviano]

Hi - I have a list returned from popen/readlines, and am wondering how
to go about iterating over each item which was returned (rather than
currently having the whole lot returned).

so far:

returns ['host1 host2 host3 ... hostN\n]'

i'd like to be in a position to iterate through these, grabbing each
host. I have played with transmuting to a str, and using split, and
this works, but I get the subscript brackets from the list output as
expected, as the list output is now a string literal, and this is not
what I want - and I think it's a bit long-winded to do a search 'n
replace on it - hence why I ask in the subject what's the best way.
["['host1","host2", ... ,"hostN\n']"]

If the file is really big, you may want not to construct an actual
list with all the words, but instead use an iterator. If you define
the function

def ichain(seq):
for s in seq:
for x in s: yield x

(which is often useful and I don't think it has been included in
itertools) you can iterate lazily on the file:

hosts = ichain(s.split() for s in f)
for host in hosts:
# ...

HTH,
Giuseppe

 

[castironpi]

Hi - I have a list returned from popen/readlines, and am wondering how
to go about iterating over each item which was returned (rather than
currently having the whole lot returned).

so far:
returns ['host1 host2 host3 ... hostN\n]'

i'd like to be in a position to iterate through these, grabbing each
host.  I have played with transmuting to a str, and using split, and
this works, but I get the subscript brackets from the list output as
expected, as the list output is now a string literal, and this is not
what I want - and I think it's a bit long-winded to do a search 'n
replace on it - hence why I ask in the subject what's the best way.

f=str(f)
f.split()

["['host1","host2", ... ,"hostN\n']"]

If the file is really big, you may want not to construct an actual  
list with all the words, but instead use an iterator. If you define  
the function

def ichain(seq):
        for s in seq:
                for x in s: yield x

(which is often useful and I don't think it has been included in  
itertools) you can iterate lazily on the file:

hosts = ichain(s.split() for s in f)
for host in hosts:
        # ...

HTH,
Giuseppe- Hide quoted text -

- Show quoted text -

I am having trouble following, but I am not an always-rightter. Was
s.split( ) one of the things you wanted to do to a line, and likely a
really common one? I'm trying to approach problems impractically.

Now of course, if anything else is going on in the program, you will
need separate threads or separate interpreters/processes. Does Python
meet sufficiencies on threading? What file do we have to test it on?

 

[Peter Otten]

def ichain(seq):
        for s in seq:
                for x in s: yield x

(which is often useful and I don't think it has been included in  
itertools) you can iterate lazily on the file:

Python 2.6 includes itertools.chain.from_iterable() with that functionality.

Peter

 

[castironpi]

Python 2.6 includes itertools.chain.from_iterable() with that functionality.

Peter

Can you color the help manual with very fine shades of off-white to
ease reading? I was thinking a few pixels shy of red of white to
accentuate what are the class methods and which are not. I also have
an argument that net readability would decrease, but the sample sizes
on that kind of metric are a little brinky with privacy fears around
where I'm from. I just try to make Tron rings.

 

[castironpi]

Can you color the help manual with very fine shades of off-white to
ease reading?  I was thinking a few pixels shy of red of white to
accentuate what are the class methods and which are not.  I also have
an argument that net readability would decrease, but the sample sizes
on that kind of metric are a little brinky with privacy fears around
where I'm from.  I just try to make Tron rings.

I am also me the that's the readability of legibles on color of light
the lighterers.

More simply, that could vary widely though, and I've heard of a
'fovea'.

 

[castironpi]

I am also me the that's the readability of legibles on color of light
the lighterers.

More simply, that could vary widely though, and I've heard of a
'fovea'.- Hide quoted text -

- Show quoted text -

Furthermore "Optical Sensors and Sensing Systems for Natural Resources
and Food Safety and Quality" from wixipedia omits sex. for Food and
Sex. I think concepts are related to perceptions. food.

 

[castironpi]

So f is a list, rather than a file object, of which os.open would have
returned (my initial typo redirected the missive of this post, sorry!)

        Other than the facet that os.open() is low-level C file object and
not a Python file object...

        What you have returned is a list of lines... Hmmm, if os.popen()
supports .readlines() it might even support direct iteration

for ln in os.popen():
        do something with the line

        Now the matter comes down to what each line looks like... It is NOT
a "list" in Python terms, no matter what delimiters it has (and one of
your examples doesn't even seem to be consistant -- [' .... ]' is not
the same as [' .... '] )

        For space separated hostnames....

for ln in os.popen(...):        #assuming it works without a preread
        for host in ln.split():
                do something with host...
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