efficient updating of nested dictionaries

**Edward C. Jones** · Jul 18 '05, 07:54 AM

Re: efficient updating of nested dictionaries

omission9 wrote:[color=blue]
> I have a dictionary that looks like this
> MY_DICT[KEY_X][KEY_Y][KEY_Z]=FOO
>
> I am having a problem updating this with a simple
> MY_DICT.update( NEW_DICT) as update doesn't seem to care about getting
> into the inner dicts.
> Getting the keys of each and iterating through and updating each one is
> terribly slow as the number of keys gets bigger and bigger.
> What is the bst way to update my nested dicts?[/color]

Make a table whose rows are (KEY_X, KEY_Y, KEY_Z, FOO). If the table is
large use MySQL or some other database. For small or medium sized tables
try "http://members.tripod. com/~edcjones/MultiDict.py".

**Rich Krauter** · Jul 18 '05, 07:54 AM

Re: efficient updating of nested dictionaries

The following is probably too dependent on the data type of the keys,
but it may be suitable in some programs. It's certainly not a general
solution for all cases. Others will have much better ideas, but here
goes anyway ...

You may want to use a non-nested dict with a 'superkey' composed of the
concatenation of the three keys, seperated by some delimiter.
use MY_DICT[KEY_X+'_'+KEY_Y +'_'+KEY_Z]=FOO

Then you could use update().You would just have to do some pre- and
post-processing of the keys. i.e. splitting or joining the 'superkey' by
the delimiter you choose.

Although, that's probably kind of lame - I bet others will have much
better suggestions. I'm interested in how other people do this too.
Rich

On Sun, 2004-01-25 at 21:33, omission9 wrote:
[color=blue]
> I have a dictionary that looks like this
> MY_DICT[KEY_X][KEY_Y][KEY_Z]=FOO
>
> I am having a problem updating this with a simple
> MY_DICT.update( NEW_DICT) as update doesn't seem to care about getting
> into the inner dicts.
> Getting the keys of each and iterating through and updating each one is
> terribly slow as the number of keys gets bigger and bigger.
> What is the bst way to update my nested dicts?
>
>[/color]

**omission9** · Jul 18 '05, 07:54 AM

Re: efficient updating of nested dictionaries

omission9 wrote:
[color=blue]
> I have a dictionary that looks like this
> MY_DICT[KEY_X][KEY_Y][KEY_Z]=FOO
>
> I am having a problem updating this with a simple
> MY_DICT.update( NEW_DICT) as update doesn't seem to care about getting
> into the inner dicts.
> Getting the keys of each and iterating through and updating each one is
> terribly slow as the number of keys gets bigger and bigger.
> What is the bst way to update my nested dicts?
>
>
>[/color]
So far I have found this on the internet:
def rUpdate(self,ta rgetDict,itemDi ct):
valtab=[]
for key,val in itemDict.items( ):
if type(val)==type ({}):
newTarget=targe tDict.setdefaul t(key,{})
self.rUpdate(ne wTarget,val)
else:
targetDict[key]=val

However, this does not seem to handle the fact that each dict has
multiple keys. :( So far the modification I have made to make it work
right have failed. Any ideas?

**Josiah Carlson** · Jul 18 '05, 07:54 AM

Re: efficient updating of nested dictionaries

> Although, that's probably kind of lame - I bet others will have much[color=blue]
> better suggestions. I'm interested in how other people do this too.
> Rich[/color]

String concatenation is not that lame, but I'd use tuples:
MY_DICT[(KEY_X, KEY_Y, KEY_Z)] = FOO

Tuples save on string operations.

- Josiah

**Sidharthk** · Jul 18 '05, 07:54 AM

Re: efficient updating of nested dictionaries

omission9 <omission9@inva lid.email.info> wrote in message news:<H%_Qb.260 9$925.1917@nwrd dc02.gnilink.ne t>...[color=blue]
> I have a dictionary that looks like this
> MY_DICT[KEY_X][KEY_Y][KEY_Z]=FOO
>
> I am having a problem updating this with a simple
> MY_DICT.update( NEW_DICT) as update doesn't seem to care about getting
> into the inner dicts.
> Getting the keys of each and iterating through and updating each one is
> terribly slow as the number of keys gets bigger and bigger.
> What is the bst way to update my nested dicts?[/color]

Use a tuple
MY_DICT[(KEY_X,KEY_Y,KE Y_Z)]=FOO

unless you have a particular reason to use these nested dicts :)

**Sidharthk** · Jul 18 '05, 07:54 AM

Re: efficient updating of nested dictionaries

omission9 <omission9@inva lid.email.info> wrote in message news:<H%_Qb.260 9$925.1917@nwrd dc02.gnilink.ne t>...[color=blue]
> I have a dictionary that looks like this
> MY_DICT[KEY_X][KEY_Y][KEY_Z]=FOO
>
> I am having a problem updating this with a simple
> MY_DICT.update( NEW_DICT) as update doesn't seem to care about getting
> into the inner dicts.
> Getting the keys of each and iterating through and updating each one is
> terribly slow as the number of keys gets bigger and bigger.
> What is the bst way to update my nested dicts?[/color]

Use Tuples

MY_DICT[(KEY_X,KEY_Y,KE Y_Z)]=FOO

Unless for some you need to use nested dicts :)

**Sidharthk** · Jul 18 '05, 07:54 AM

Re: efficient updating of nested dictionaries

omission9 <omission9@inva lid.email.info> wrote in message news:<H%_Qb.260 9$925.1917@nwrd dc02.gnilink.ne t>...[color=blue]
> I have a dictionary that looks like this
> MY_DICT[KEY_X][KEY_Y][KEY_Z]=FOO
>
> I am having a problem updating this with a simple
> MY_DICT.update( NEW_DICT) as update doesn't seem to care about getting
> into the inner dicts.
> Getting the keys of each and iterating through and updating each one is
> terribly slow as the number of keys gets bigger and bigger.
> What is the bst way to update my nested dicts?[/color]

Use Tuples

MY_DICT[(KEY_X,KEY_Y,KE Y_Z)]=FOO

Unless for some you need to use nested dicts :)

**Duncan Booth** · Jul 18 '05, 07:54 AM

Re: efficient updating of nested dictionaries

Josiah Carlson <jcarlson@nospa m.uci.edu> wrote in
news:bv2e21$j5e $2@news.service .uci.edu:
[color=blue][color=green]
>> Although, that's probably kind of lame - I bet others will have much
>> better suggestions. I'm interested in how other people do this too.
>> Rich[/color]
>
> String concatenation is not that lame, but I'd use tuples:
> MY_DICT[(KEY_X, KEY_Y, KEY_Z)] = FOO
>
> Tuples save on string operations.[/color]

I would omit the extra parentheses here, but its a style thing.

MY_DICT[KEY_X, KEY_Y, KEY_Z] = FOO

(Note to original poster: I'd also turn off caps-lock)

**Sidharthk** · Jul 18 '05, 07:54 AM

Re: efficient updating of nested dictionaries

This is untested code but i think it should work.(fingers crossed)
Btw i doubt this will be fast though.

def rec_update(mydi ct, newdict):
presentKeysPair s = [(key,value)
for (key, value) in newdict.items()
if mydict.has_key( key)]
newKeysPairs = [(key,value)
for (key, value) in newdict,items()
if not mydict.has_key( key)]
for key, newValue in presentKeysPair s:
currentValue = mydict[key]
if isisntance(newV alue, dict):
mydict[key] = rec_update(newV alue)
else:
mydict[key] = newValue
mydict.update(d ict(newKeysPair s))
return mydict

regards

ps. why can't you simply use tuples to represent the different
dimensions, even if the number of dimensions vary.
is there any particular reason why you are using these nested
dictionaries?

**Rich Krauter** · Jul 18 '05, 07:55 AM

Re: efficient updating of nested dictionaries

>> String concatenation is not that lame, but I'd use tuples:[color=blue][color=green]
>> MY_DICT[(KEY_X, KEY_Y, KEY_Z)] = FOO
>> Tuples save on string operations.[/color][/color]

What a nice way to simplify this common task. That's great. Thanks for
the advice.
Rich

**Ben Finney** · Jul 18 '05, 07:55 AM

Re: efficient updating of nested dictionaries

On Mon, 26 Jan 2004 20:11:39 -0500, Rich Krauter wrote:[color=blue]
> What a nice way to simplify this common task. That's great. Thanks for
> the advice.
>
> [HTML garbage repeating the same content][/color]

What a hideous way to complicate this simple medium. That sucks.
Thanks for turning it off in future.

--
\ "My roommate got a pet elephant. Then it got lost. It's in the |
`\ apartment somewhere." -- Steven Wright |
_o__) |
Ben Finney <http://bignose.squidly .org/>

**Rich Krauter** · Jul 18 '05, 07:55 AM

Re: efficient updating of nested dictionaries

Oh crap. Sorry about the html emails. I've been meaning to turn that
off. Thanks for reminding me.
Rich

**Ben Finney** · Jul 18 '05, 07:55 AM

Re: efficient updating of nested dictionaries

On Mon, 26 Jan 2004 21:32:28 -0500, Rich Krauter wrote:[color=blue]
> Oh crap. Sorry about the html emails. I've been meaning to turn that
> off. Thanks for reminding me.[/color]

Much better! Thanks for being considerate.

--
\ "When I turned two I was really anxious, because I'd doubled my |
`\ age in a year. I thought, if this keeps up, by the time I'm six |
_o__) I'll be ninety." -- Steven Wright |
Ben Finney <http://bignose.squidly .org/>

efficient updating of nested dictionaries

efficient updating of nested dictionaries

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