Reading a file, sans whitespace

[Uri]

I have a file that looks like this: (but longer, no wordwrap)

Name: Date: Time: Company: Employee Number:
Jim 2.03.04 12:00 JimEnt 4
Steve 3.04.32 03:00 SteveEnt 5

I want to load 'Jim' and '12:00' and those types of answers into
variables in my program, the only delimiter in the file is whitespace.
How do I do this?

I can do it with string.split(" ",[0]) type line for a file that's
only delimited by single spaces, but when I'm searching for white
space, how do I do it?

THanks!

[Michael Geary]

Uri wrote:

I have a file that looks like this: (but longer, no wordwrap)

Name: Date: Time: Company: Employee Number:
Jim 2.03.04 12:00 JimEnt 4
Steve 3.04.32 03:00 SteveEnt 5

I want to load 'Jim' and '12:00' and those types of answers
into variables in my program, the only delimiter in the file
is whitespace. How do I do this?

I can do it with string.split(" ",[0]) type line for a file that's
only delimited by single spaces, but when I'm searching
for white space, how do I do it?

Use a regular expression. For speed, precompile it at the beginning of your
program:

reWhitespace = re.compile( r'\s+' )

Then, split each line with:

fields = reWhitespace.sp lit( line )

-Mike

[Rick L. Ratzel]

How about this:

import re
for line in open( "inputFile" , "r" ).readlines(): .... print re.split( "\s+", line.strip() )
....
['Name:', 'Date:', 'Time:', 'Company:', 'Employee', 'Number:']
['Jim', '2.03.04', '12:00', 'JimEnt', '4']
['Steve', '3.04.32', '03:00', 'SteveEnt', '5']

-Rick Ratzel
Uri wrote: I have a file that looks like this: (but longer, no wordwrap)

Name: Date: Time: Company: Employee Number:
Jim 2.03.04 12:00 JimEnt 4
Steve 3.04.32 03:00 SteveEnt 5

I want to load 'Jim' and '12:00' and those types of answers into
variables in my program, the only delimiter in the file is whitespace.
How do I do this?

I can do it with string.split(" ",[0]) type line for a file that's
only delimited by single spaces, but when I'm searching for white
space, how do I do it?

THanks!

[Tim Daneliuk]

Uri wrote:

I have a file that looks like this: (but longer, no wordwrap)

Name: Date: Time: Company: Employee Number:
Jim 2.03.04 12:00 JimEnt 4
Steve 3.04.32 03:00 SteveEnt 5

I want to load 'Jim' and '12:00' and those types of answers into
variables in my program, the only delimiter in the file is whitespace.
How do I do this?

I can do it with string.split(" ",[0]) type line for a file that's
only delimited by single spaces, but when I'm searching for white
space, how do I do it?

THanks!

Say you have read a line in the above format into variable 's'.
Then,

l = s.split()

will return a list containing each of the fields of the line as
an entry with the whitespace stripped out. Then,

VarName = l[0]
VarDate = l[1]
VarTime = l[2]
VarCo = l[3]
VarEmp = l[4]
Is this what you had in mind?

--
----------------------------------------------------------------------------
Tim Daneliuk tu****@tundrawa re.com
PGP Key: http://www.tundraware.com/PGP/

[Michael Geary]

> Uri wrote:

I have a file that looks like this: (but longer, no wordwrap)

Name: Date: Time: Company: Employee Number:
Jim 2.03.04 12:00 JimEnt 4
Steve 3.04.32 03:00 SteveEnt 5

I want to load 'Jim' and '12:00' and those types of answers into
variables in my program, the only delimiter in the file is whitespace.
How do I do this?

I can do it with string.split(" ",[0]) type line for a file that's
only delimited by single spaces, but when I'm searching for white
space, how do I do it?

THanks!

Tim Daneliuk wrote: Say you have read a line in the above format into variable 's'.
Then,

l = s.split()

will return a list containing each of the fields of the line as
an entry with the whitespace stripped out. Then,

VarName = l[0]
VarDate = l[1]
VarTime = l[2]
VarCo = l[3]
VarEmp = l[4]

D'oh! That's much better than the regular expression solution I posted.

The regular expression split is good to know about for more complicated
patterns, but for simple whitespace splitting there's no need for it.

Thanks,

-Mike

[Uri]

> Tim Daneliuk wrote:

Say you have read a line in the above format into variable 's'.
Then,

l = s.split()

will return a list containing each of the fields of the line as
an entry with the whitespace stripped out. Then,

VarName = l[0]
VarDate = l[1]
VarTime = l[2]
VarCo = l[3]
VarEmp = l[4]

D'oh! That's much better than the regular expression solution I posted.

The regular expression split is good to know about for more complicated
patterns, but for simple whitespace splitting there's no need for it.

Thanks,

-Mike

Thanks guys! Tim's idea seems like the easiest for a newbie to
implement, but I'll play around with Mike's pre-compiling thing, too.
I don't really understand what the compile part does, could you
expound upon that?

Thanks for all your help guys!

[Konstantin Veretennicov]

"Michael Geary" <Mi**@DeleteThi s.Geary.com> wrote in message news:<10******* ******@corp.sup ernews.com>...

import re
reWhitespace = re.compile( '\s+' )
for line in file( 'inputFile' ).readlines():
print reWhitespace.sp lit( line.strip() )

But for a large file, the second version will be faster because the regular

And you'll want to use "for line in file('inputFile ')"
instead of "for line in file('inputFile ').readlines()" ,
especially for large files ;)

- kv

[Terry Reedy]

"Michael Geary" <Mi**@DeleteThi s.Geary.com> wrote in message
news:10******** *****@corp.supe rnews.com...

Uri wrote:
For example, these do exactly the same thing:

import re
for line in file( 'inputFile' ).readlines():
print re.split( '\s+', line.strip() )

import re
reWhitespace = re.compile( '\s+' )
for line in file( 'inputFile' ).readlines():
print reWhitespace.sp lit( line.strip() )

But for a large file, the second version will be faster because the regular expression is compiled only once instead of every time through the loop.

I am curious whether you have actually timed this or seen others timings.
My impression (from other posts and from reading the code a year ago) is
that the current re implementation caches compiled re's
(recache[hash(restring)] = re.compile(rest ring)) just so that the first
example will *not* recompile every time thru the loop. If so, I think one
should name an re for pretty much the same reasons as for anything else:
conceptual chunking and reuse in multiple places.

Terry J. Reedy

[Michael Geary]

> Michael Geary wrote:

For example, these do exactly the same thing:

import re
for line in file( 'inputFile' ).readlines():
print re.split( '\s+', line.strip() )

import re
reWhitespace = re.compile( '\s+' )
for line in file( 'inputFile' ).readlines():
print reWhitespace.sp lit( line.strip() )

But for a large file, the second version will be faster because
the regular expression is compiled only once instead of every
time through the loop.

Terry Reedy wrote: I am curious whether you have actually timed this or seen others
timings. My impression (from other posts and from reading the
code a year ago) is that the current re implementation caches
compiled re's (recache[hash(restring)] = re.compile(rest ring))
just so that the first example will *not* recompile every time thru
the loop. If so, I think one should name an re for pretty much the
same reasons as for anything else: conceptual chunking and reuse
in multiple places.

Oh man, is my face red! No, I didn't know about the caching, and I hadn't
timed this. One should never make assumptions about performance issues! :-)

Also, as Konstantin pointed out, file( 'inputFile' ).readlines() should be
just file( 'inputFile' ), and I just noticed that I didn't use raw strings
for the regular expressions. '\s+' happens to work, but it would be better
to be in the habit of writing r'\s+' instead. This was not my day for
posting good code samples!

Now that you've shamed me into actually testing the performance, it turns
out that precompiling the regular expression does make a difference.
Consider these examples:

import re, time
input = []
for i in xrange( 1000000 ):
input.append( '%d abc def ghi jkl mno pqr stu' % i )
start = time.time()
for line in input:
result = re.split( r'\s+', line )
print time.time() - start

import re, time
input = []
for i in xrange( 1000000 ):
input.append( '%d abc def ghi jkl mno pqr stu' % i )
start = time.time()
reWhitespace = re.compile( r'\s+' )
for line in input:
result = reWhitespace.sp lit( line )
print time.time() - start

On my PIII-1.2GHz system, the first version runs in 27 seconds, and the
second version runs in 18 seconds, quite an improvement. I would guess that
the hash lookup for the cached regular expression is what's taking the extra
time in the first version, but I don't want to assume that's what it is. :-)

-Mike