Stripping whitespace

[ryan k]

Hello. I have a string like 'LNAME
PASTA   ZONE'. I want to create a list of those words and
basically replace all the whitespace between them with one space so i
could just do lala.split(). Thank you!

Ryan Kaskel
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Re: Stripping whitespace

[Marc 'BlackJack' Rintsch]

On Wed, 23 Jan 2008 10:50:02 -0800, ryan k wrote:

> Hello. I have a string like 'LNAME
> PASTA   ZONE'. I want to create a list of those words and
> basically replace all the whitespace between them with one space so i
> could just do lala.split(). Thank you!

You *can* just do ``lala.split()``:

In [97]: lala = 'LNAME   PASTA   ZONE'

In [98]: lala.split()
Out[98]: ['LNAME', 'PASTA', 'ZONE']

Ciao,
Marc 'BlackJack' Rintsch
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Re: Stripping whitespace

[Paul Rubin]

ryan k <[EMAIL PROTECTED]> writes:
> Hello. I have a string like 'LNAME
> PASTA   ZONE'. I want to create a list of those words and
> basically replace all the whitespace between them with one space so i
> could just do lala.split(). Thank you!

import re
s = 'LNAME  PASTAZONE'
re.split('\s+', s)
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Re: Stripping whitespace

[James Matthews]

Using the split method is the easiest!

On 23 Jan 2008 19:04:38 GMT, Marc 'BlackJack' Rintsch <[EMAIL PROTECTED]> wrote:
> On Wed, 23 Jan 2008 10:50:02 -0800, ryan k wrote:
>
> > Hello. I have a string like 'LNAME
> > PASTA   ZONE'. I want to create a list of those words and
> > basically replace all the whitespace between them with one space so i
> > could just do lala.split(). Thank you!
>
> You *can* just do ``lala.split()``:
>
> In [97]: lala = 'LNAME   PASTA   ZONE'
>
> In [98]: lala.split()
> Out[98]: ['LNAME', 'PASTA', 'ZONE']
>
> Ciao,
> Marc 'BlackJack' Rintsch
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>



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Re: Stripping whitespace

[ryan k]

On Jan 23, 2:04 pm, Marc 'BlackJack' Rintsch <[EMAIL PROTECTED]> wrote:
> On Wed, 23 Jan 2008 10:50:02 -0800, ryan k wrote:
> > Hello. I have a string like 'LNAME
> > PASTA   ZONE'. I want to create a list of those words and
> > basically replace all the whitespace between them with one space so i
> > could just do lala.split(). Thank you!
>
> You *can* just do ``lala.split()``:

Indeed you can thanks!

>
> In [97]: lala = 'LNAME   PASTA   ZONE'
>
> In [98]: lala.split()
> Out[98]: ['LNAME', 'PASTA', 'ZONE']
>
> Ciao,
> Marc 'BlackJack' Rintsch

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Re: Stripping whitespace

[ryan k]

I am taking a database class so I'm not asking for specific answers.
Well I have this text tile:

http://www.cs.tufts.edu/comp/115/projects/proj0/customer.txt

And this code:

# Table and row classes used for queries

class Row(object):
def __init__(self, column_list, row_vals):
print len(column_list)
print len(row_vals)
for column, value in column_list, row_vals:
if column and value:
setattr(self, column.lower(), value)

class Table(object):
def __init__(self, table_name, table_fd):
self.name = table_name
self.table_fd = table_fd
self.rows = []
self._load_table()

def _load_table(self):
counter = 0
for line in self.table_fd:
# Skip the second line
if not '-' in line:
if counter == 0:
# This line contains the columns, parse it
column_list = line.split()
else:
# This is a row, parse it
row_vals = line.split()
# Create a new Row object and add it to the
table's
# row list
self.rows.append(Row(column_list, row_vals))
counter += 1

Because the addresses contain spaces, this won't work because there
are too many values being unpacked in row's __init__'s for loop. Any
suggestions for a better way to parse this file? I don't want to cheat
but just some general ideas would be nice. Thanks!
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Re: Stripping whitespace

[John Machin]

On Jan 24, 5:50 am, ryan k <[EMAIL PROTECTED]> wrote:
> Hello. I have a string like 'LNAME
> PASTA   ZONE'. I want to create a list of those words and
> basically replace all the whitespace between them with one space so i
> could just do lala.split(). Thank you!
>
> Ryan Kaskel

So when you go to the Python interactive prompt and type firstly
lala = 'LNAME PASTA ZONE'
and then
lala.split()
what do you see, and what more do you need to meet your requirements?
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Re: Stripping whitespace

[John Machin]

On Jan 24, 6:05 am, Paul Rubin  wrote:
> ryan k <[EMAIL PROTECTED]> writes:
> > Hello. I have a string like 'LNAME
> > PASTA   ZONE'. I want to create a list of those words and
> > basically replace all the whitespace between them with one space so i
> > could just do lala.split(). Thank you!
>
> import re
> s = 'LNAME  PASTAZONE'
> re.split('\s+', s)

That is (a) excessive for the OP's problem as stated and (b) unlike
str.split will cause him to cut you out of his will if his problem
turns out to include leading/trailing whitespace:

>>> lala = '   LNAME   PASTA   ZONE   '
>>> import re
>>> re.split(r'\s+', lala)
['', 'LNAME', 'PASTA', 'ZONE', '']
>>> lala.split()
['LNAME', 'PASTA', 'ZONE']
>>>
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Re: Stripping whitespace

[John Machin]

On Jan 24, 6:17 am, ryan k <[EMAIL PROTECTED]> wrote:
> I am taking a database class so I'm not asking for specific answers.
> Well I have this text tile:
>
> http://www.cs.tufts.edu/comp/115/projects/proj0/customer.txt

Uh-huh, "column-aligned" output.

>
> And this code:
>
[snip]

>
> Because the addresses contain spaces, this won't work because there
> are too many values being unpacked in row's __init__'s for loop. Any
> suggestions for a better way to parse this file?


Tedious (and dumb) way:
field0 = line[start0:end0+1].rstrip()
field1 = line[start1:end1+1].rstrip()
etc

Why dumb: if the column sizes change, you have to suffer the tedium
again. While your sample appears to pad out each field to some
predetermined width, some reporting software (e.g. the Query Analyzer
that comes with MS SQL Server) will tailor the widths to the maximum
size actually observed in the data in each run of the report ... so
you write your program based on some tiny test output and next day you
run it for real and there's a customer whose name is Marmaduke
Rubberduckovitch-Featherstonehaugh or somesuch and your name is mud.

Smart way: note that the second line (the one with all the dashes)
gives you all the information you need to build lists of start and end
positions.
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Re: Stripping whitespace

[ryan k]

On Jan 23, 2:53 pm, John Machin <[EMAIL PROTECTED]> wrote:
> On Jan 24, 6:17 am, ryan k <[EMAIL PROTECTED]> wrote:
>
> > I am taking a database class so I'm not asking for specific answers.
> > Well I have this text tile:
>
> >http://www.cs.tufts.edu/comp/115/projects/proj0/customer.txt
>
> Uh-huh, "column-aligned" output.
>
>
>
> > And this code:
>
> [snip]
>
>
>
> > Because the addresses contain spaces, this won't work because there
> > are too many values being unpacked in row's __init__'s for loop. Any
> > suggestions for a better way to parse this file?
>
> Tedious (and dumb) way:
> field0 = line[start0:end0+1].rstrip()
> field1 = line[start1:end1+1].rstrip()
> etc
>
> Why dumb: if the column sizes change, you have to suffer the tedium
> again. While your sample appears to pad out each field to some
> predetermined width, some reporting software (e.g. the Query Analyzer
> that comes with MS SQL Server) will tailor the widths to the maximum
> size actually observed in the data in each run of the report ... so
> you write your program based on some tiny test output and next day you
> run it for real and there's a customer whose name is Marmaduke
> Rubberduckovitch-Featherstonehaugh or somesuch and your name is mud.
>
> Smart way: note that the second line (the one with all the dashes)
> gives you all the information you need to build lists of start and end
> positions.

Thank you for your detailed response Mr. Machin. The teacher *said*
that the columns were supposed to be tab delimited but they aren't. So
yea i will just have to count dashes. Thank you!
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Re: Stripping whitespace

[John Machin]

On Jan 24, 6:57 am, ryan k <[EMAIL PROTECTED]> wrote:

> So yea i will just have to count dashes.

Read my lips: *you* counting dashes is dumb. Writing your code so that
*code* is counting dashes each time it opens the file is smart.

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Re: Stripping whitespace

[ryan k]

On Jan 23, 3:02 pm, John Machin <[EMAIL PROTECTED]> wrote:
> On Jan 24, 6:57 am, ryan k <[EMAIL PROTECTED]> wrote:
>
> > So yea i will just have to count dashes.
>
> Read my lips: *you* counting dashes is dumb. Writing your code so that
> *code* is counting dashes each time it opens the file is smart.

Okay it's almost working ...

new parser function:

def _load_table(self):
counter = 0
for line in self.table_fd:
# Skip the second line
if counter == 0:
# This line contains the columns, parse it
column_list = line.split()
elif counter == 1:
# These are the dashes
line_l = line.split()
column_width = [len(i) for i in line_l]
print column_width
else:
# This is a row, parse it
marker = 0
row_vals = []
for col in column_width:
start = sum(column_width[:marker])
finish = sum(column_width[:marker+1])
print line[start:finish].strip()
row_vals.append(line[start:finish].strip())
marker += 1
self.rows.append(Row(column_list, row_vals))
counter += 1

Something obvious you can see wrong with my start finish code?

['rimon', 'rimon', 'Barr', 'Rimon', '22 Greenside Cres., Thornhill, ON
L3T 6W9', '2', '', 'm', '102', '100
-', '22.13 1234567890', '[EMAIL PROTECTED]', '']
['UNAME', 'PASSWD', 'LNAME', 'FNAME', 'ADDR', 'ZONE', 'SEX', 'AGE',
'LIMIT', 'BALANCE', 'CREDITCARD', 'EMAIL',
 'ACTIVE']
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RE: Stripping whitespace

[Reedick, Andrew]

> -Original Message-
> From: [EMAIL PROTECTED] [mailto:python-
> [EMAIL PROTECTED] On Behalf Of ryan k
> Sent: Wednesday, January 23, 2008 3:24 PM
> To: python-list@python.org
> Subject: Re: Stripping whitespace
> 
> On Jan 23, 3:02 pm, John Machin <[EMAIL PROTECTED]> wrote:
> > On Jan 24, 6:57 am, ryan k <[EMAIL PROTECTED]> wrote:
> >
> > > So yea i will just have to count dashes.
> >
> > Read my lips: *you* counting dashes is dumb. Writing your code so
> that
> > *code* is counting dashes each time it opens the file is smart.
> 
> Okay it's almost working ...
> 

Why is it that so many Python people are regex adverse?  Use the dashed
line as a regex.  Convert the dashes to dots.  Wrap the dots in
parentheses.  Convert the whitespace chars to '\s'.  Presto!  Simpler,
cleaner code.

import re

state = 0
header_line = ''
pattern = ''
f = open('a.txt', 'r')
for line in f:
if line[-1:] == '\n':
line = line[:-1]

if state == 0:
header_line = line
state += 1
elif state == 1:
pattern = re.sub(r'-', r'.', line)
pattern = re.sub(r'\s', r'\\s', pattern)
pattern = re.sub(r'([.]+)', r'(\1)', pattern)
print pattern
state += 1

headers = re.match(pattern, header_line)
if headers:
print headers.groups()
else:
state = 2
m = re.match(pattern, line)
if m:
print m.groups()


f.close()



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Re: Stripping whitespace

[John Machin]

On Jan 24, 7:23 am, ryan k <[EMAIL PROTECTED]> wrote:
> On Jan 23, 3:02 pm, John Machin <[EMAIL PROTECTED]> wrote:
>
> > On Jan 24, 6:57 am, ryan k <[EMAIL PROTECTED]> wrote:
>
> > > So yea i will just have to count dashes.
>
> > Read my lips: *you* counting dashes is dumb. Writing your code so that
> > *code* is counting dashes each time it opens the file is smart.
>
> Okay it's almost working ...
>
> new parser function:
>
> def _load_table(self):
> counter = 0
> for line in self.table_fd:
> # Skip the second line

The above comment is a nonsense.

> if counter == 0:
> # This line contains the columns, parse it
> column_list = line.split()

In generality, you would have to allow for the headings to contain
spaces as well -- this means *saving* a reference to the heading line
and splitting it *after* you've processed the line with the dashes.

> elif counter == 1:
> # These are the dashes
> line_l = line.split()
> column_width = [len(i) for i in line_l]

Whoops.
column_width = [len(i) + 1 for i in line_l]

> print column_width
> else:
> # This is a row, parse it
> marker = 0
> row_vals = []
> for col in column_width:
> start = sum(column_width[:marker])
> finish = sum(column_width[:marker+1])
> print line[start:finish].strip()

If you had printed just line[start:finish], it would have been obvious
what the problem was. See below for an even better suggestion.

> row_vals.append(line[start:finish].strip())
> marker += 1

Using sum is a tad ugly. Here's an alternative:

row_vals = []
start = 0
for width in column_width:
finish = start + width
#DEBUG# print repr(line[start:finish].replace(' ', '~'))
row_vals.append(line[start:finish].strip())
start = finish

> self.rows.append(Row(column_list, row_vals))
> counter += 1
>
> Something obvious you can see wrong with my start finish code?

See above.

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Re: Stripping whitespace

[Steven D'Aprano]

On Wed, 23 Jan 2008 11:05:01 -0800, Paul Rubin wrote:

> ryan k <[EMAIL PROTECTED]> writes:
>> Hello. I have a string like 'LNAME
>> PASTA   ZONE'. I want to create a list of those words and
>> basically replace all the whitespace between them with one space so i
>> could just do lala.split(). Thank you!
> 
> import re
> s = 'LNAME  PASTAZONE'
> re.split('\s+', s)

Please tell me you're making fun of the poor newbie and didn't mean to 
seriously suggest using a regex merely to split on whitespace?

>>> import timeit
>>> timeit.Timer("s.split()", "s = 'one   two  three four'").repeat()
[1.4074358940124512, 1.3505148887634277, 1.3469438552856445]
>>> timeit.Timer("re.split('\s+', s)", "import re;s = 'one   two  
three four'").repeat()
[7.9205508232116699, 7.8833441734313965, 7.9301259517669678]





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Re: Stripping whitespace

[ryan k]

On Jan 23, 5:37 pm, Steven D'Aprano <[EMAIL PROTECTED]
cybersource.com.au> wrote:
> On Wed, 23 Jan 2008 11:05:01 -0800, Paul Rubin wrote:
> > ryan k <[EMAIL PROTECTED]> writes:
> >> Hello. I have a string like 'LNAME
> >> PASTA   ZONE'. I want to create a list of those words and
> >> basically replace all the whitespace between them with one space so i
> >> could just do lala.split(). Thank you!
>
> > import re
> > s = 'LNAME  PASTAZONE'
> > re.split('\s+', s)
>
> Please tell me you're making fun of the poor newbie and didn't mean to
> seriously suggest using a regex merely to split on whitespace?
>
> >>> import timeit
> >>> timeit.Timer("s.split()", "s = 'one   two  three four'").repeat()
>
> [1.4074358940124512, 1.3505148887634277, 1.3469438552856445]>>> 
> timeit.Timer("re.split('\s+', s)", "import re;s = 'one   two
>
> three four'").repeat()
> [7.9205508232116699, 7.8833441734313965, 7.9301259517669678]
>
> --
> Steven

The main topic is not an issue anymore.
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Re: Stripping whitespace

[John Machin]

On Jan 24, 7:57 am, "Reedick, Andrew" <[EMAIL PROTECTED]> wrote:
>
> Why is it that so many Python people are regex adverse?  Use the dashed
> line as a regex.  Convert the dashes to dots.  Wrap the dots in
> parentheses.  Convert the whitespace chars to '\s'.  Presto!  Simpler,
> cleaner code.

Woo-hoo! Yesterday was HTML day, today is code review day. Yee-haa!

>
> import re
>
> state = 0
> header_line = ''
> pattern = ''
> f = open('a.txt', 'r')
> for line in f:
> if line[-1:] == '\n':
> line = line[:-1]
>
> if state == 0:
> header_line = line
> state += 1

state = 1

> elif state == 1:
> pattern = re.sub(r'-', r'.', line)
> pattern = re.sub(r'\s', r'\\s', pattern)
> pattern = re.sub(r'([.]+)', r'(\1)', pattern)

Consider this:
pattern = ' '.join('(.{%d})' % len(x) for x in line.split())

> print pattern
> state += 1

state = 2

>
> headers = re.match(pattern, header_line)
> if headers:
> print headers.groups()
> else:
> state = 2

assert state == 2

> m = re.match(pattern, line)
> if m:
> print m.groups()
>
> f.close()
>
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Re: Stripping whitespace

[John Machin]

On Jan 24, 9:47 am, ryan k <[EMAIL PROTECTED]> wrote:
> On Jan 23, 5:37 pm, Steven D'Aprano <[EMAIL PROTECTED]
>
>
>
> cybersource.com.au> wrote:
> > On Wed, 23 Jan 2008 11:05:01 -0800, Paul Rubin wrote:
> > > ryan k <[EMAIL PROTECTED]> writes:
> > >> Hello. I have a string like 'LNAME
> > >> PASTA   ZONE'. I want to create a list of those words and
> > >> basically replace all the whitespace between them with one space so i
> > >> could just do lala.split(). Thank you!
>
> > > import re
> > > s = 'LNAME  PASTAZONE'
> > > re.split('\s+', s)
>
> > Please tell me you're making fun of the poor newbie and didn't mean to
> > seriously suggest using a regex merely to split on whitespace?
>
> > >>> import timeit
> > >>> timeit.Timer("s.split()", "s = 'one   two  three four'").repeat()
>
> > [1.4074358940124512, 1.3505148887634277, 1.3469438552856445]>>> 
> > timeit.Timer("re.split('\s+', s)", "import re;s = 'one   two
>
> > three four'").repeat()
> > [7.9205508232116699, 7.8833441734313965, 7.9301259517669678]
>
> > --
> > Steven
>
> The main topic is not an issue anymore.

We know that. This thread will continue with biffo and brickbats long
after your assignment has been submitted :-)
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Re: Stripping whitespace

[ryan k]

On Jan 23, 5:37 pm, Steven D'Aprano <[EMAIL PROTECTED]
cybersource.com.au> wrote:
> On Wed, 23 Jan 2008 11:05:01 -0800, Paul Rubin wrote:
> > ryan k <[EMAIL PROTECTED]> writes:
> >> Hello. I have a string like 'LNAME
> >> PASTA   ZONE'. I want to create a list of those words and
> >> basically replace all the whitespace between them with one space so i
> >> could just do lala.split(). Thank you!
>
> > import re
> > s = 'LNAME  PASTAZONE'
> > re.split('\s+', s)
>
> Please tell me you're making fun of the poor newbie and didn't mean to
> seriously suggest using a regex merely to split on whitespace?
>
> >>> import timeit
> >>> timeit.Timer("s.split()", "s = 'one   two  three four'").repeat()
>
> [1.4074358940124512, 1.3505148887634277, 1.3469438552856445]>>> 
> timeit.Timer("re.split('\s+', s)", "import re;s = 'one   two
>
> three four'").repeat()
> [7.9205508232116699, 7.8833441734313965, 7.9301259517669678]
>
> --
> Steven

Much thanks to Machin for helping with the parsing job. Steven
D'Aprano, you are a prick.
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Re: Stripping whitespace

[John Machin]

On Jan 24, 9:50 am, ryan k <[EMAIL PROTECTED]> wrote:

> Steven D'Aprano, you are a prick.

And your reasons for coming to that stridently expressed conclusion
after reading a posting that was *not* addressed to you are .?

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Re: Stripping whitespace

[ryan k]

On Jan 23, 6:30 pm, John Machin <[EMAIL PROTECTED]> wrote:
> On Jan 24, 9:50 am, ryan k <[EMAIL PROTECTED]> wrote:
>
> > Steven D'Aprano, you are a prick.
>
> And your reasons for coming to that stridently expressed conclusion
> after reading a posting that was *not* addressed to you are .?

Because his tone is extremely condescending and quite frankly
annoying. From this post to others, his terse remarks scar this
community and fade its atmosphere of friendliness.
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Re: Stripping whitespace

[cokofreedom]

On Jan 24, 8:21 am, ryan k <[EMAIL PROTECTED]> wrote:
> On Jan 23, 6:30 pm, John Machin <[EMAIL PROTECTED]> wrote:
>
> > On Jan 24, 9:50 am, ryan k <[EMAIL PROTECTED]> wrote:
>
> > > Steven D'Aprano, you are a prick.
>
> > And your reasons for coming to that stridently expressed conclusion
> > after reading a posting that was *not* addressed to you are .?
>
> Because his tone is extremely condescending and quite frankly
> annoying. From this post to others, his terse remarks scar this
> community and fade its atmosphere of friendliness.

And your response was any better because...?
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RE: Stripping whitespace

[Reedick, Andrew]

> -Original Message-
> From: [EMAIL PROTECTED] [mailto:python-
> [EMAIL PROTECTED] On Behalf Of John Machin
> Sent: Wednesday, January 23, 2008 5:48 PM
> To: python-list@python.org
> Subject: Re: Stripping whitespace
> 
> On Jan 24, 7:57 am, "Reedick, Andrew" <[EMAIL PROTECTED]> wrote:
> >
> > Why is it that so many Python people are regex adverse?  Use the
> dashed
> > line as a regex.  Convert the dashes to dots.  Wrap the dots in
> > parentheses.  Convert the whitespace chars to '\s'.  Presto!
> Simpler,
> > cleaner code.
> 
> > pattern = re.sub(r'-', r'.', line)
> > pattern = re.sub(r'\s', r'\\s', pattern)
> > pattern = re.sub(r'([.]+)', r'(\1)', pattern)
> 
> Consider this:
> pattern = ' '.join('(.{%d})' % len(x) for x in line.split())
> 

Good.  But the main drawback to using split+join is that it works if
there is only one whitespace char acting as a column separator
(split+join will compress multiple whitespace characters down to one
char.)  Normally, it's safe to assume a one character separator between
columns, however since the input is supposed to be tab delimited (but
wasn't) and tabs tend to get randomly converted to spaces depending on
which butterfly is flapping its wings at any given instant, keeping the
original whitespace column separators is probably a good idea.



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