Select as dictionary...

[Besturk.Net Admin]

Hi..
I am using python with postgresql.
And i have a query :

aia.execute("SE LECT id, w from list")
links=aia.fetch all()
print links

and result
[(1, 5), (2,5).......] (2 million result)

I want to see this result directly as a dictionary:

{1: 5, 2: 5 .....}

How do i select in this format ?

I'm sorry my bad english.

King Regards...

[Bruno Desthuilliers]

Besturk.Net Admin a écrit :

Hi..
I am using python with postgresql.
And i have a query :

aia.execute("SE LECT id, w from list")
links=aia.fetch all()
print links

and result
[(1, 5), (2,5).......] (2 million result)

I want to see this result directly as a dictionary:

{1: 5, 2: 5 .....}

How do i select in this format ?

IIRC, postgres' db-api connector (well, at least one of them - I don't
know which one you're using) has a DictCursor. You should find all you
want to know in the relevant doc.

FWIW:
http://www.initd.org/tracker/psycopg/wiki/PsycopgTwoFaq

HTH

[J. Clifford Dyer]

On Mon, Oct 01, 2007 at 06:32:07AM -0700, Besturk.Net Admin wrote regarding Select as dictionary...:

>
aia.execute("SE LECT id, w from list")
links=aia.fetch all()
print links

and result
[(1, 5), (2,5).......] (2 million result)

I want to see this result directly as a dictionary:

{1: 5, 2: 5 .....}

How do i select in this format ?

Try this:

aia.execute("SE LECT id, w from list")
links=aia.fetch all()
linkdict = dict()
for k,v in links:
linkdict[k] = v
print linkdict
Cheers,
Cliff

[Stargaming]

On Mon, 01 Oct 2007 09:57:46 -0400, J. Clifford Dyer wrote:

On Mon, Oct 01, 2007 at 06:32:07AM -0700, Besturk.Net Admin wrote
regarding Select as dictionary...:

>>
aia.execute("S ELECT id, w from list") links=aia.fetch all()
print links

and result
[(1, 5), (2,5).......] (2 million result)

I want to see this result directly as a dictionary:

{1: 5, 2: 5 .....}

How do i select in this format ?

Try this:

aia.execute("SE LECT id, w from list")
links=aia.fetch all()
linkdict = dict()
for k,v in links:
linkdict[k] = v
print linkdict

Besides using the already pointed out DB adapters, you can easily
transform a list of items into a dictionary with the `dict` constructor::

>>links = [(1, 5), (2, 5), (3, 10)]
dict(links)

{1: 5, 2: 5, 3: 10}

Stargaming

[M.-A. Lemburg]

On 2007-10-01 15:32, Besturk.Net Admin wrote:

Hi..
I am using python with postgresql.
And i have a query :

aia.execute("SE LECT id, w from list")
links=aia.fetch all()
print links

and result
[(1, 5), (2,5).......] (2 million result)

I want to see this result directly as a dictionary:

{1: 5, 2: 5 .....}

How do i select in this format ?

You can easily convert the above list to a dictionary:

d = dict(links)

--
Marc-Andre Lemburg
eGenix.com

Professional Python Services directly from the Source (#1, Oct 01 2007)

>>Python/Zope Consulting and Support ... http://www.egenix.com/
mxODBC.Zope.D atabase.Adapter ... http://zope.egenix.com/
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Registered at Amtsgericht Duesseldorf: HRB 46611

[Duncan Booth]

"J. Clifford Dyer" <jc*@sdf.lonest ar.orgwrote:

aia.execute("SE LECT id, w from list")
links=aia.fetch all()
linkdict = dict()
for k,v in links:
linkdict[k] = v
print linkdict

Wouldn't it be simpler just to do:

aia.execute("SE LECT id, w from list")
linkdict=dict(a ia.fetchall())

even better would be to use an iterator to avoid fetching the entire
resultset as a list.

[Carsten Haese]

On Mon, 2007-10-01 at 09:57 -0400, J. Clifford Dyer wrote:

On Mon, Oct 01, 2007 at 06:32:07AM -0700, Besturk.Net Admin wrote regarding Select as dictionary...:

aia.execute("SE LECT id, w from list")
links=aia.fetch all()
print links

and result
[(1, 5), (2,5).......] (2 million result)

I want to see this result directly as a dictionary:

{1: 5, 2: 5 .....}

How do i select in this format ?

Try this:

aia.execute("SE LECT id, w from list")
links=aia.fetch all()
linkdict = dict()
for k,v in links:
linkdict[k] = v
print linkdict

Improvement 1: Use the fact that dict can be initialized from a sequence
of key/value pairs:

aia.execute("SE LECT id, w from list")
linkdict = dict(aia.fetcha ll())

Improvement 2: Use an iterator instead of reading all rows into memory:

aia.execute("SE LECT id, w from list")
linkdict = dict(iter(aia.f etchone,None))

--
Carsten Haese
http://informixdb.sourceforge.net

[Carsten Haese]

On Mon, 2007-10-01 at 15:50 +0200, Bruno Desthuilliers wrote:

Besturk.Net Admin a écrit :

I want to see this result directly as a dictionary:

{1: 5, 2: 5 .....}

How do i select in this format ?

IIRC, postgres' db-api connector (well, at least one of them - I don't
know which one you're using) has a DictCursor.

That would return the results as a list of dictionaries like this:

[{'id':1, 'w':5}, {'id':2, 'w':5}, ...]

--
Carsten Haese
http://informixdb.sourceforge.net

[Carsten Haese]

linkdict = dict(iter(aia.f etchone,None))

And by the way, that line can be shortened to "linkdict=dict( aia)" if
the cursor object supports the iterator protocol, but that's not a
mandatory feature in DB-API v2. The longer form is guaranteed to work
with any DB-API v2 compliant implementation.

--
Carsten Haese
http://informixdb.sourceforge.net

[J. Clifford Dyer]

On Mon, Oct 01, 2007 at 10:12:04AM -0400, Carsten Haese wrote regarding Re: Select as dictionary...:

>
On Mon, 2007-10-01 at 09:57 -0400, J. Clifford Dyer wrote:

>

Try this:

aia.execute("SE LECT id, w from list")
links=aia.fetch all()
linkdict = dict()
for k,v in links:
linkdict[k] = v
print linkdict

Improvement 1: Use the fact that dict can be initialized from a sequence
of key/value pairs:

aia.execute("SE LECT id, w from list")
linkdict = dict(aia.fetcha ll())

This is only an improvement if the SQL query remains a list of 2-tuples. If the OP wants to add more values, the more verbose version allows for easier extensibility.

for k,v1,v2 in links:
linkdict[k] = (v1, v2)

Of course even better would be not to have to add variables, so maybe:

for link in links:
linkdict[link[0]] = link[1:],

which changes the output format somewhat, but keeps the access by dict keyed to the DB id.

Improvement 2: Use an iterator instead of reading all rows into memory:

aia.execute("SE LECT id, w from list")
linkdict = dict(iter(aia.f etchone,None))

Agreed. A much better solution.

Cheers,
Cliff