Hello
I found that price of += operator on string is too high in jython. For
example 5000 such operations took 90 seconds (i generated html copy of
table with 1000 rows and 5 columns). Generation of row data into separate
string and joining after lead to time 13 seconds !!!
What's alternative way to do that ? (similiar parts of my code are terribbly
slow and such simple solution as above didn't help).
Thanks,
Jan 5 6906
> I found that price of += operator on string is too high in jython. For example 5000 such operations took 90 seconds (i generated html copy of table with 1000 rows and 5 columns). Generation of row data into separate string and joining after lead to time 13 seconds !!!
Its generally not recommended to use simple string concatenation for
building larger strings - neither in python nor in java/jython.
afaik there are two solutions to this: The java-way and the jython way:
java: Use StringBuffer
python: use a list, and append the strings to that. Then, when you want the
result, do
"".join(stringl ist)
--
Regards,
Diez B. Roggisch
Jan Gregor wrote: Hello
I found that price of += operator on string is too high in jython. For example 5000 such operations took 90 seconds (i generated html copy of table with 1000 rows and 5 columns). Generation of row data into separate string and joining after lead to time 13 seconds !!!
What's alternative way to do that ? (similiar parts of my code are terribbly slow and such simple solution as above didn't help).
I don't use Jython, but are you not able to do something like:
string_list = []
for ... in ...:
...
string_list.app end(...)
...
string = ''.join(string_ list)
This is the usual Python idiom and is usually faster than the += idiom.
Note too that +ing strings in Java also has this problem -- hence
StringBuffer or whatever it's called.
Steve
Ok, thanks. I didn't think that += operator is nondestructive operation
- but strings are immutable so this makes sense.
On 2004-12-13, Diez B. Roggisch <de*********@we b.de> wrote: I found that price of += operator on string is too high in jython. For example 5000 such operations took 90 seconds (i generated html copy of table with 1000 rows and 5 columns). Generation of row data into separate string and joining after lead to time 13 seconds !!!
Its generally not recommended to use simple string concatenation for building larger strings - neither in python nor in java/jython.
afaik there are two solutions to this: The java-way and the jython way:
java: Use StringBuffer python: use a list, and append the strings to that. Then, when you want the result, do
"".join(stringl ist)
StringBuffer class from java was right solution - yours looses encoding,
and in jython I was unable to get it back - in python it worked fine.
Jan I don't use Jython, but are you not able to do something like:
string_list = [] for ... in ...: ... string_list.app end(...) ... string = ''.join(string_ list)
This is the usual Python idiom and is usually faster than the += idiom.
Note too that +ing strings in Java also has this problem -- hence StringBuffer or whatever it's called.
Steve
Jan Gregor wrote: StringBuffer class from java was right solution - yours looses encoding, and in jython I was unable to get it back - in python it worked fine.
If you mean that Jython returned a string, when the inputs were unicode, then
that can probably be fixed with:
result = u''.join(string _list)
(Python switches to the unicode version automatically if it finds any unicode
strings in the supplied sequence. Jython may not do that - I'm not a Jython user
though, so I'm not sure).
Cheers,
Nick.
--
Nick Coghlan | nc******@email. com | Brisbane, Australia
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