Convert string to command..

[Abandoned]

I want to convert a string to command..
For example i have a string:
a="['1']"
I want to do this list..
How can i do ?

[Adam Atlas]

On Oct 18, 10:23 am, Abandoned <best...@gmail. comwrote:

I want to convert a string to command..
For example i have a string:
a="['1']"
I want to do this list..
How can i do ?

Use the builtin function "eval".

[Diez B. Roggisch]

Abandoned wrote:

I want to convert a string to command..
For example i have a string:
a="['1']"
I want to do this list..
How can i do ?

The correct wording here would be expression. To evaluate expressions, there
is the function eval:

a = eval("['1']")

But beware: if the expression contains some potentially harmful code, it
will be executed. So it is generally considered bad style to use eval.

An example that fails would be

a = eval("10**2000* *2000")

or such thing.

Another alternative is to use parsers like simplejson to extract the
information. This of course only works, if your expressions are valid json.

Diez

[Abandoned]

Thanks you all answer..
But "eval" is very slow at very big dictionary {2:3,4:5,6:19.. ..}
(100.000 elements)
Is there any easy alternative ?

[Diez B. Roggisch]

Abandoned wrote:

Thanks you all answer..
But "eval" is very slow at very big dictionary {2:3,4:5,6:19.. ..}
(100.000 elements)
Is there any easy alternative ?

How big? How slow? For me, a 10000-element list takes 0.04 seconds to be
parsed. Which I find fast.

Diez

[Abandoned]

On Oct 18, 6:14 pm, "Diez B. Roggisch" <de...@nospam.w eb.dewrote:

Abandoned wrote:

Thanks you all answer..
But "eval" is very slow at very big dictionary {2:3,4:5,6:19.. ..}
(100.000 elements)
Is there any easy alternative ?

How big? How slow? For me, a 10000-element list takes 0.04 seconds to be
parsed. Which I find fast.

Diez

173.000 dict elements and it tooks 2.2 seconds this very big time for
my project

[Hrvoje Niksic]

Abandoned <be*****@gmail. comwrites:

173.000 dict elements and it tooks 2.2 seconds this very big time
for my project

If you're generating the string from Python, use cPickle instead.
Much faster:

>>import time
d = dict((i, i+1) for i in xrange(170000))
len(d)

170000

>>s=repr(d)
t0 = time.time(); d2 = eval(s); t1 = time.time()
t1-t0

1.5457899570465 088

>>import cPickle as pickle
s = pickle.dumps(d, -1)
len(s)

1437693

>>t0 = time.time(); d2 = pickle.loads(s) ; t1 = time.time()
t1-t0

0.0603079795837 40234

>>len(d2)

170000

That is 25x speedup. Note that cPickle's format is binary. Using the
textual format makes for more readable pickles, but reduces the
speedup to "only" 9.5x on my machine.
P.S.
Before someone says that using pickle is unsafe, remember that he is
considering *eval* as the alternative. :-)

[Diez B. Roggisch]

Abandoned wrote:

On Oct 18, 6:14 pm, "Diez B. Roggisch" <de...@nospam.w eb.dewrote:

>Abandoned wrote:

Thanks you all answer..
But "eval" is very slow at very big dictionary {2:3,4:5,6:19.. ..}
(100.000 elements)
Is there any easy alternative ?

How big? How slow? For me, a 10000-element list takes 0.04 seconds to be
parsed. Which I find fast.

Diez

173.000 dict elements and it tooks 2.2 seconds this very big time for
my project

Where does the data come from?

Diez

[Abandoned]

On Oct 18, 6:26 pm, Hrvoje Niksic <hnik...@xemacs .orgwrote:

Abandoned <best...@gmail. comwrites:

173.000 dict elements and it tooks 2.2 seconds this very big time
for my project

If you're generating the string from Python, use cPickle instead.
Much faster:

>import time
d = dict((i, i+1) for i in xrange(170000))
len(d)

170000

>s=repr(d)
t0 = time.time(); d2 = eval(s); t1 = time.time()
t1-t0

1.5457899570465 088

>import cPickle as pickle
s = pickle.dumps(d, -1)
len(s)

1437693

>t0 = time.time(); d2 = pickle.loads(s) ; t1 = time.time()
t1-t0

0.0603079795837 40234>>len(d2)

170000

That is 25x speedup. Note that cPickle's format is binary. Using the
textual format makes for more readable pickles, but reduces the
speedup to "only" 9.5x on my machine.

P.S.
Before someone says that using pickle is unsafe, remember that he is
considering *eval* as the alternative. :-)

import cPickle as pickle
a="{2:3,4:6,2:7 }"
s=pickle.dumps( a, -1)
g=pickle.loads( s);
print g
'{2:3,4:6,2:7}'

Thank you very much for your answer but result is a string ??

[Abandoned]

On Oct 18, 6:51 pm, Marc 'BlackJack' Rintsch <[e-mail] wrote:

On Thu, 18 Oct 2007 08:41:30 -0700, Abandoned wrote:

import cPickle as pickle
a="{2:3,4:6,2:7 }"
s=pickle.dumps( a, -1)
g=pickle.loads( s);
print g
'{2:3,4:6,2:7}'

Thank you very much for your answer but result is a string ??

In Python terms yes, strings in Python can contain any byte value. If you
want to put this into a database you need a BLOB column or encode it as
base64 or something similar more ASCII safe.

Ciao,
Marc 'BlackJack' Rintsch

'{2:3,4:6,2:7}' already in database, i select this and convert to real
dictionary..