Re: [Tutor] Is there a better way to get a current mid-rate Yen quote with Python?

[Dick Moores]

At 04:11 PM 7/25/2008, Alan Gauld wrote:

"Dick Moores" <[EMAIL PROTECTED]> wrote
Certainly Beautiful Soup will not be muh longer and a lot more 
elegant and probably more resilient.

Alan, expand a bit, please. Longer? Resilient?


Longer as in lines of code. BS is good for extracting several 
different parts from the soup, but just to pull out one very 
specific item the setup and so on may mean that the framework 
actually works out the same or longer than your code.


Resilient as in able to handle unexpected changes in the HTML used 
by the site or slight changes in formatting of the results etc.


But to extract a single piece of text in a well defined location 
then your approach although somewhat crude will work just fine.

Crude? What's crude about my code?


Its just a little bit too hard coded for my liking, all that 
splitting and searching means theres a lot of work going on
to extract a small piece of data. You iterate over the whole page to 
do the first spliot,


Ah. I had the idea that it would be better to split it into its 
natural lines, by line 7.  But I could have just started with the 
first relevant split.


 then you iterate over the whole thing again to find the line you 
want. Consider thios line:


if 'JPY' in x and '>USDJPY=X<' in x:

Sincy JPY is in both strings the first check is effectively 
redundant but still requires a string search over the line.
A well crafted regex would probably be faster than the double in 
test and provide better checking by including

allowances for extra spaces or case changes etc.


I'll try to do that.

Then having found the string once with 'in' you then have to find it 
again with split().


Do you mean string x? After c = x (line 10), the next split is on c. 
I'm not finding it again, am I?


 You could just have done a find the first time and stored the 
index as a basis for the slicing later.


You also use lots of very specific slicing values to extract the 
data - thats where you lose resilience compared to a parser approach like BS.


Since I posted I found that I could add some resilience by extending 
the end of the slice and then cutting back with an rstrip().


I haven't the slightest idea what a parser is. But I'll find out 
while learning BS.


 Again I suspect a regex might work better in extracting the value. 
And hard coding the url in the function also adds to its fragility.


I can't imagine what else is possible?

Stylistically all those single character variable names hurts 
readability and maintainability too.


I was at a loss as to what variable names to use, so I figured I'd 
use a, b, c, .. in order, because I thought it was obvious that I was 
narrowing the search for the yen rate. Could you give me an idea of 
what names I could use?



I want to improve, so please tell


It will work as is, but it could be tidied up a bit is all.


Thanks Alan, for your tough look at the code. I appreciate it.

Dick
===
Have you seen Kelie Feng's video introducing the terrific and free
IDE, Ulipad? 
Get Ulipad 3.9 from 
svn for the latest revision 
Mailing list for Ulipad: 

___
Tutor maillist  -  Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor

Re: [Tutor] Is there a better way to get a current mid-rate Yen quote with Python?

[Alan Gauld]

"Dick Moores" <[EMAIL PROTECTED]> wrote 

Certainly Beautiful Soup will not be muh longer and a lot more 
elegant and probably more resilient.


Alan, expand a bit, please. Longer? Resilient?


Longer as in lines of code. BS is good for extracting several 
different parts from the soup, but just to pull out one very 
specific item the setup and so on may mean that the 
framework actually works out the same or longer than 
your code.


Resilient as in able to handle unexpected changes in 
the HTML used by the site or slight changes in formatting 
of the results etc.


But to extract a single piece of text in a well defined location 
then your approach although somewhat crude will work just fine.


Crude? What's crude about my code? 


Its just a little bit too hard coded for my liking, all that 
splitting and searching means theres a lot of work going on
to extract a small piece of data. You iterate over the whole 
page to do the first spliot, then you iterate over the whole 
thing again to find the line you want. Consider thios line:


if 'JPY' in x and '>USDJPY=X<' in x:

Sincy JPY is in both strings the first check is effectively 
redundant but still requires a string search over the line.
A well crafted regex would probably be faster than the 
double in test and provide better checking by including

allowances for extra spaces or case changes etc.

Then having found the string once with 'in' you them have 
to find it again with split(). You could just have done 
a find the first time and stored the index as a basis for 
the slicing later.


You also use lots of very specific slicing values to extract the 
data - thats where you lose resilience compared to a parser 
approach like BS. Again I suspect a regex might work better 
in extracting the value. And hard coding the url in the function 
also adds to its fragility.


Stylistically all those single character variable names hurts 
readability and maintainability too. 

I want to improve, so please tell 


It will work as is, but it could be tidied up a bit is all.

Alan G.

___
Tutor maillist  -  Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor

Re: [Tutor] Is there a better way to get a current mid-rate Yen quote with Python?

[Dick Moores]

At 09:47 AM 7/25/2008, Alan Gauld wrote:

"Dick Moores" <[EMAIL PROTECTED]> wrote

Here's one opinion, an answer to my second question.
Dick


And to answer your first: It depends on how you define better.

Certainly Beautiful Soup will not be muh longer and a lot more 
elegant and probably more resilient.


Alan, expand a bit, please. Longer? Resilient?


But to extract a single piece of text in a well defined location 
then your approach although somewhat crude will work just fine.


Crude? What's crude about my code? I want to improve, so please tell 
me. 


Thanks,

Dick
===
Have you seen Kelie Feng's video introducing the terrific and free
IDE, Ulipad? 
Get Ulipad 3.9 from 
svn for the latest revision 
Mailing list for Ulipad: 

___
Tutor maillist  -  Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor

Re: [Tutor] Is there a better way to get a current mid-rate Yen quote with Python?

[Alan Gauld]

"Dick Moores" <[EMAIL PROTECTED]> wrote 


Here's one opinion, an answer to my second question.

Dick


And to answer your first: It depends on how you define better.

Certainly Beautiful Soup will not be muh longer and a lot more 
elegant and probably more resilient.


But to extract a single piece of text in a well defined location 
then your approach although somewhat crude will work just fine.


Alan G

___
Tutor maillist  -  Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor

Re: [Tutor] Is there a better way to get a current mid-rate Yen quote with Python?

[Dick Moores]

Here's one opinion, an answer to my second question.
Dick
Date: Fri, 25 Jul 2008 08:54:53 -0500
From: "W W" <[EMAIL PROTECTED]>
To: "Dick Moores" <[EMAIL PROTECTED]>
Subject: Re: [Tutor] Is there a better way to get a current mid-rate Yen
quote with Python?
Beautiful Soup is really awesome... I've used it a little, and I'd say
it's totally worth learning.
-Wayne
On Fri, Jul 25, 2008 at 7:14 AM, Dick Moores
<[EMAIL PROTECTED]> wrote:


Better than this?
<
http://py77.python.pastebin.com/fc7553a4>

I've heard about BeautifulSoup.
<
http://www.crummy.com/software/BeautifulSoup/>. Is it worth
learning? Is it crummy? ;-)

So 2 questions.

Thanks,

Dick Moores




___
Tutor maillist  -  Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor

[Tutor] Is there a better way to get a current mid-rate Yen quote with Python?

[Dick Moores]

Better than this? 

I've heard about BeautifulSoup. 
. Is it worth 
learning? Is it crummy? ;-)


So 2 questions.

Thanks,

Dick Moores

___
Tutor maillist  -  Tutor@python.org
http://mail.python.org/mailman/listinfo/tutor