Re: Multiple values for one key
Hi,
try defaultdict:
In [1]: from collections import defaultdict
In [2]: d=defaultdict(list)
In [3]: d[1].append(7)
In [4]: d[1].append(8)
In [5]: d
Out[5]: defaultdict(type 'list', {1: [7, 8]})
In [6]: d[1]
Out[6]: [7, 8]
Regards,
wr
Am Donnerstag 28 August 2008 19:02:55 schrieb Ron Brennan:
I have another question.
How would like to be able to add the contents on the values for one key.
key['20001']:[978, 345]
How can I do this?
Thanks,
Ron
On Thu, Aug 28, 2008 at 11:56 AM, Bruno Desthuilliers
[EMAIL PROTECTED] wrote:
norseman a écrit :
Terry Reedy wrote:
Ron Brennan wrote:
Hello,
How would I create a dictionary that contains multiple values for
one key.
Make the value a collection object (set or list if you plan to add and
delete).
I'd also like the key to be able to have duplicate entries.
Dict keys must be hashable and unique.
tjr
--
http://mail.python.org/mailman/listinfo/python-list
First part I understand, second is still giving me a problem.
For some reason I still want keys to be dbf column headers.
like:
name:address:zip so forth
--- --- --
guy: unknown:0
girl: 123 tiny street:12345
boy:321 here:3
gal:999 over there: 5
so forth
Thus one key has many values. And you can then index on whatever key(s)
you wish - name,zip...
You can either use 1/ a list of dicts, or 2/ a dict mapping keys to
lists.
1/
records = [
{name:guy, address:unknown,zip:0},
{name:girl, address:123 tiny street,zip:12345},
{name:boy, address:321 here,zip:3},
{name:gal, address:999 over there,zip:5},
]
keys = (name, address, zip)
print :.join(keys)
print - * len(:.join(keys))
for record in records:
data = [record[key] for key in keys]
print :.join(data)
2/
records = dict(
name=[guy, girl, boy, gal],
address=[unknown,123 tiny street,321 there,999 over there],
zip=[0, 12345, 3, 5]
)
keys = (name, address, zip)
nb_records = len(records[keys[0]])
print :.join(keys)
print - * len(:.join(keys))
for i in xrange(nb_records):
data = [data[key][i] for key in keys]
print :.join(data)
You are of course entitled the right to prefer the second solution, but
then I hope I'll never have to maintain your code, since it's obviously
not an appropriate data structure.
With billions plus records,
With billions plus records, it may be time to move to a serious RDBMS.
Which btw will provide solution 1, or a lighter version of it using a
list of tuples, ie:
cursor = connection.cursor()
cursor.execute(select name, address, zip from peoples)
records = cursor.fetchall()
# at this time, you have :
#records = [
# (guy, unknown,0,),
# (girl, 123 tiny street,12345,),
# (boy, 321 here,3,),
# (gal, 999 over there, 5,),
#]
(snip)
OK - I know I missed the whole concept of a Python Dictionary.
Bad thing for you, since it's the central datastructure in Python.
I haven't read anything as yet that gives a clear picture of what it is
and
what it is for.
Then you failed to read the FineManual's tutorial, which is where you
should have started:
http://docs.python.org/tut/node7.html#SECTION00750
Do yourself a favour : read the above first, then if you still have
questions about dicts, we'll gladly try to help.
And do yourself another favour : learn about SQL, relational model and
RDBMS.
(snip description of why the OP *really* wants a RDBMS)
--
http://mail.python.org/mailman/listinfo/python-list
--
http://mail.python.org/mailman/listinfo/python-list
Re: Multiple values for one key
Le Thursday 28 August 2008 03:43:16 norseman, vous avez écrit :
Terry Reedy wrote:
Ron Brennan wrote:
Hello,
How would I create a dictionary that contains multiple values for one
key.
Make the value a collection object (set or list if you plan to add and
delete).
I'd also like the key to be able to have duplicate entries.
Dict keys must be hashable and unique.
tjr
--
http://mail.python.org/mailman/listinfo/python-list
First part I understand, second is still giving me a problem.
For some reason I still want keys to be dbf column headers.
like:
name:address:zip so forth
--- --- --
guy: unknown:0
girl: 123 tiny street:12345
boy:321 here:3
gal:999 over there: 5
so forth
Thus one key has many values. And you can then index on whatever key(s)
you wish - name,zip...
With billions plus records, trying to put a unique key on each entry
seems to preclude the need for a dictionary, just use the entries.
(Format to SDF and index on substr(line,1,24)+substr(line,48,+5) etc..)
name+ zip
OK - I know I missed the whole concept of a Python Dictionary. I haven't
read anything as yet that gives a clear picture of what it is and what
it is for. Please, classroom concepts usually consist of a handful of
objects. I have files here that takes up multiple DVDs each, AFTER a 15
to 1 compression. 3 bytes per pixel. I need to work with them. Things
like changing geobase projections and cookie cutting based on real world
coordinates and modifying the lumens and so forth. Based on what I've
read, the Python Dictionary concept flat will not work for such as this.
Yes - the example is overkill. But in my world it is reality. I deal
with sizeable things. Not all are raster. Most all are binary! Things
that work on massive text files - like banking and mortgage - simply
don't work here. There are seldom 'lines'. There are always bytes. Lots
of bytes. Things that form a group are not necessarily stored sequentially.
Back to What Is A Python Dictionary: Somebody please enlighten me.
Disctionaries are hash tables with a unique key and constant time lookup. What
you want could be implemented as a complex data structures with as many dict
as needed keys, but it seems you really want a relational table and a rdbms.
This is exactly what they are for. A short example with the new python2.5
sqlite package :
[107]: import sqlite3
[108]: from string import letters
[109]: db = sqlite3.connect(':memory:')
[110]: db.execute(create table 'table1' ('name' text(20), 'address'
text(100), primary key ('name', 'address')))
...[110]: sqlite3.Cursor object at 0x2b0cd9712c38
[111]: db.executemany(insert into 'table1' values (?, ?),
((letters[i%len(letters)]*i, %d street % i) for i in range(1000))).rowcount
...[111]: 1000
[112]: for i in db.execute(select * from 'table1' where address
like '99 %') : print i
.:
(u'VVV',
u'99 street')
[113]: for i in db.execute(select * from 'table1' where name
like '___') : print i
.:
(u'ddd', u'3 street')
[114]: db.execute(insert into 'table1' values (?, ?), ('ddd', '4
street')).rowcount
...[114]: 1
[115]: for i in db.execute(select * from 'table1' where name
like '___') : print i
.:
(u'ddd', u'3 street')
(u'ddd', u'4 street')
[116]: db.execute(insert into 'table1' values (?, ?), ('ddd', '4
street')).rowcount
---
IntegrityErrorTraceback (most recent call last)
/home/maric/ipython console in module()
IntegrityError: columns name, address are not unique
Steve
[EMAIL PROTECTED]
--
http://mail.python.org/mailman/listinfo/python-list
--
_
Maric Michaud
--
http://mail.python.org/mailman/listinfo/python-list
Re: Multiple values for one key
norseman a écrit :
Terry Reedy wrote:
Ron Brennan wrote:
Hello,
How would I create a dictionary that contains multiple values for one
key.
Make the value a collection object (set or list if you plan to add and
delete).
I'd also like the key to be able to have duplicate entries.
Dict keys must be hashable and unique.
tjr
--
http://mail.python.org/mailman/listinfo/python-list
First part I understand, second is still giving me a problem.
For some reason I still want keys to be dbf column headers.
like:
name:address:zip so forth
--- --- --
guy: unknown:0
girl: 123 tiny street:12345
boy:321 here:3
gal:999 over there: 5
so forth
Thus one key has many values. And you can then index on whatever key(s)
you wish - name,zip...
You can either use 1/ a list of dicts, or 2/ a dict mapping keys to lists.
1/
records = [
{name:guy, address:unknown,zip:0},
{name:girl, address:123 tiny street,zip:12345},
{name:boy, address:321 here,zip:3},
{name:gal, address:999 over there,zip:5},
]
keys = (name, address, zip)
print :.join(keys)
print - * len(:.join(keys))
for record in records:
data = [record[key] for key in keys]
print :.join(data)
2/
records = dict(
name=[guy, girl, boy, gal],
address=[unknown,123 tiny street,321 there,999 over there],
zip=[0, 12345, 3, 5]
)
keys = (name, address, zip)
nb_records = len(records[keys[0]])
print :.join(keys)
print - * len(:.join(keys))
for i in xrange(nb_records):
data = [data[key][i] for key in keys]
print :.join(data)
You are of course entitled the right to prefer the second solution, but
then I hope I'll never have to maintain your code, since it's obviously
not an appropriate data structure.
With billions plus records,
With billions plus records, it may be time to move to a serious RDBMS.
Which btw will provide solution 1, or a lighter version of it using a
list of tuples, ie:
cursor = connection.cursor()
cursor.execute(select name, address, zip from peoples)
records = cursor.fetchall()
# at this time, you have :
#records = [
# (guy, unknown,0,),
# (girl, 123 tiny street,12345,),
# (boy, 321 here,3,),
# (gal, 999 over there, 5,),
#]
(snip)
OK - I know I missed the whole concept of a Python Dictionary.
Bad thing for you, since it's the central datastructure in Python.
I haven't
read anything as yet that gives a clear picture of what it is and what
it is for.
Then you failed to read the FineManual's tutorial, which is where you
should have started:
http://docs.python.org/tut/node7.html#SECTION00750
Do yourself a favour : read the above first, then if you still have
questions about dicts, we'll gladly try to help.
And do yourself another favour : learn about SQL, relational model and
RDBMS.
(snip description of why the OP *really* wants a RDBMS)
--
http://mail.python.org/mailman/listinfo/python-list
Re: Multiple values for one key
2008/8/28 Bruno Desthuilliers [EMAIL PROTECTED]:
You can either use 1/ a list of dicts, or 2/ a dict mapping keys to lists.
1/
records = [
{name:guy, address:unknown,zip:0},
{name:girl, address:123 tiny street,zip:12345},
{name:boy, address:321 here,zip:3},
{name:gal, address:999 over there,zip:5},
]
I think I'd make a class with members name, address, zip, etc. Then
make a list of instances of that class or (better for access) identify
a primary key -- what *is* unique about each entry -- and use that as
a dictionary key with class instances as values. Or use a DBMS.
Certainly the original poster should read up on database design, or
chances are he'll have a nightmare maintaining referential integrity.
--
Tim Rowe
--
http://mail.python.org/mailman/listinfo/python-list
Re: Multiple values for one key
I have another question.
How would like to be able to add the contents on the values for one key.
key['20001']:[978, 345]
How can I do this?
Thanks,
Ron
On Thu, Aug 28, 2008 at 11:56 AM, Bruno Desthuilliers
[EMAIL PROTECTED] wrote:
norseman a écrit :
Terry Reedy wrote:
Ron Brennan wrote:
Hello,
How would I create a dictionary that contains multiple values for one
key.
Make the value a collection object (set or list if you plan to add and
delete).
I'd also like the key to be able to have duplicate entries.
Dict keys must be hashable and unique.
tjr
--
http://mail.python.org/mailman/listinfo/python-list
First part I understand, second is still giving me a problem.
For some reason I still want keys to be dbf column headers.
like:
name:address:zip so forth
--- --- --
guy: unknown:0
girl: 123 tiny street:12345
boy:321 here:3
gal:999 over there: 5
so forth
Thus one key has many values. And you can then index on whatever key(s)
you wish - name,zip...
You can either use 1/ a list of dicts, or 2/ a dict mapping keys to lists.
1/
records = [
{name:guy, address:unknown,zip:0},
{name:girl, address:123 tiny street,zip:12345},
{name:boy, address:321 here,zip:3},
{name:gal, address:999 over there,zip:5},
]
keys = (name, address, zip)
print :.join(keys)
print - * len(:.join(keys))
for record in records:
data = [record[key] for key in keys]
print :.join(data)
2/
records = dict(
name=[guy, girl, boy, gal],
address=[unknown,123 tiny street,321 there,999 over there],
zip=[0, 12345, 3, 5]
)
keys = (name, address, zip)
nb_records = len(records[keys[0]])
print :.join(keys)
print - * len(:.join(keys))
for i in xrange(nb_records):
data = [data[key][i] for key in keys]
print :.join(data)
You are of course entitled the right to prefer the second solution, but
then I hope I'll never have to maintain your code, since it's obviously not
an appropriate data structure.
With billions plus records,
With billions plus records, it may be time to move to a serious RDBMS.
Which btw will provide solution 1, or a lighter version of it using a list
of tuples, ie:
cursor = connection.cursor()
cursor.execute(select name, address, zip from peoples)
records = cursor.fetchall()
# at this time, you have :
#records = [
# (guy, unknown,0,),
# (girl, 123 tiny street,12345,),
# (boy, 321 here,3,),
# (gal, 999 over there, 5,),
#]
(snip)
OK - I know I missed the whole concept of a Python Dictionary.
Bad thing for you, since it's the central datastructure in Python.
I haven't read anything as yet that gives a clear picture of what it is and
what it is for.
Then you failed to read the FineManual's tutorial, which is where you
should have started:
http://docs.python.org/tut/node7.html#SECTION00750
Do yourself a favour : read the above first, then if you still have
questions about dicts, we'll gladly try to help.
And do yourself another favour : learn about SQL, relational model and
RDBMS.
(snip description of why the OP *really* wants a RDBMS)
--
http://mail.python.org/mailman/listinfo/python-list
--
FYI, my email address is changing. My rogers account will be deactivated
shortly. From now on please use:
[EMAIL PROTECTED]
--
http://mail.python.org/mailman/listinfo/python-list
Re: Multiple values for one key
On Thu, Aug 28, 2008 at 10:02 AM, Ron Brennan [EMAIL PROTECTED] wrote:
I have another question.
How would like to be able to add the contents on the values for one key.
key['20001']:[978, 345]
I'm assuming that by this you meant:
assert the_dict['20001'] == [978, 345]
How can I do this?
sum(the_dict['20001']) #= 1323
Regards,
Chris
Follow the path of the Iguana...
Rebertia: http://rebertia.com
Blog: http://blog.rebertia.com
Thanks,
Ron
On Thu, Aug 28, 2008 at 11:56 AM, Bruno Desthuilliers
[EMAIL PROTECTED] wrote:
norseman a écrit :
Terry Reedy wrote:
Ron Brennan wrote:
Hello,
How would I create a dictionary that contains multiple values for one
key.
Make the value a collection object (set or list if you plan to add and
delete).
I'd also like the key to be able to have duplicate entries.
Dict keys must be hashable and unique.
tjr
--
http://mail.python.org/mailman/listinfo/python-list
First part I understand, second is still giving me a problem.
For some reason I still want keys to be dbf column headers.
like:
name:address:zip so forth
--- --- --
guy: unknown:0
girl: 123 tiny street:12345
boy:321 here:3
gal:999 over there: 5
so forth
Thus one key has many values. And you can then index on whatever key(s)
you wish - name,zip...
You can either use 1/ a list of dicts, or 2/ a dict mapping keys to lists.
1/
records = [
{name:guy, address:unknown,zip:0},
{name:girl, address:123 tiny street,zip:12345},
{name:boy, address:321 here,zip:3},
{name:gal, address:999 over there,zip:5},
]
keys = (name, address, zip)
print :.join(keys)
print - * len(:.join(keys))
for record in records:
data = [record[key] for key in keys]
print :.join(data)
2/
records = dict(
name=[guy, girl, boy, gal],
address=[unknown,123 tiny street,321 there,999 over there],
zip=[0, 12345, 3, 5]
)
keys = (name, address, zip)
nb_records = len(records[keys[0]])
print :.join(keys)
print - * len(:.join(keys))
for i in xrange(nb_records):
data = [data[key][i] for key in keys]
print :.join(data)
You are of course entitled the right to prefer the second solution, but
then I hope I'll never have to maintain your code, since it's obviously not
an appropriate data structure.
With billions plus records,
With billions plus records, it may be time to move to a serious RDBMS.
Which btw will provide solution 1, or a lighter version of it using a list
of tuples, ie:
cursor = connection.cursor()
cursor.execute(select name, address, zip from peoples)
records = cursor.fetchall()
# at this time, you have :
#records = [
# (guy, unknown,0,),
# (girl, 123 tiny street,12345,),
# (boy, 321 here,3,),
# (gal, 999 over there, 5,),
#]
(snip)
OK - I know I missed the whole concept of a Python Dictionary.
Bad thing for you, since it's the central datastructure in Python.
I haven't read anything as yet that gives a clear picture of what it is
and what it is for.
Then you failed to read the FineManual's tutorial, which is where you
should have started:
http://docs.python.org/tut/node7.html#SECTION00750
Do yourself a favour : read the above first, then if you still have
questions about dicts, we'll gladly try to help.
And do yourself another favour : learn about SQL, relational model and
RDBMS.
(snip description of why the OP *really* wants a RDBMS)
--
http://mail.python.org/mailman/listinfo/python-list
--
FYI, my email address is changing. My rogers account will be deactivated
shortly. From now on please use:
[EMAIL PROTECTED]
--
http://mail.python.org/mailman/listinfo/python-list
--
http://mail.python.org/mailman/listinfo/python-list
Multiple values for one key
Hello, How would I create a dictionary that contains multiple values for one key. I'd also like the key to be able to have duplicate entries. Thanks, Ron -- FYI, my email address is changing. My rogers account will be deactivated shortly. From now on please use: [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
Re: Multiple values for one key
Ron Brennan wrote: How would I create a dictionary that contains multiple values for one key. I'd also like the key to be able to have duplicate entries. look for the thread titled python multimap. /F -- http://mail.python.org/mailman/listinfo/python-list
Re: Multiple values for one key
Ron Brennan wrote: Hello, How would I create a dictionary that contains multiple values for one key. Make the value a collection object (set or list if you plan to add and delete). I'd also like the key to be able to have duplicate entries. Dict keys must be hashable and unique. tjr -- http://mail.python.org/mailman/listinfo/python-list
Re: Multiple values for one key
Le Thursday 28 August 2008 01:56:54 Terry Reedy, vous avez écrit : I'd also like the key to be able to have duplicate entries. Dict keys must be hashable and unique. Let's admit they don't have to be unique (it's easy to implement all sort of data structures in pure python), but what would be the syntax for modifying an existing value, for example, what should be the result of two consecutive assignements ? d[5] = None d[5] = 0 d[5] == [ None, 0 ] ?? What exactly are you trying to achieve ? -- _ Maric Michaud -- http://mail.python.org/mailman/listinfo/python-list
Re: Multiple values for one key
Terry Reedy wrote: Ron Brennan wrote: Hello, How would I create a dictionary that contains multiple values for one key. Make the value a collection object (set or list if you plan to add and delete). I'd also like the key to be able to have duplicate entries. Dict keys must be hashable and unique. tjr -- http://mail.python.org/mailman/listinfo/python-list First part I understand, second is still giving me a problem. For some reason I still want keys to be dbf column headers. like: name:address:zip so forth --- --- -- guy: unknown:0 girl: 123 tiny street:12345 boy:321 here:3 gal:999 over there: 5 so forth Thus one key has many values. And you can then index on whatever key(s) you wish - name,zip... With billions plus records, trying to put a unique key on each entry seems to preclude the need for a dictionary, just use the entries. (Format to SDF and index on substr(line,1,24)+substr(line,48,+5) etc..) name+ zip OK - I know I missed the whole concept of a Python Dictionary. I haven't read anything as yet that gives a clear picture of what it is and what it is for. Please, classroom concepts usually consist of a handful of objects. I have files here that takes up multiple DVDs each, AFTER a 15 to 1 compression. 3 bytes per pixel. I need to work with them. Things like changing geobase projections and cookie cutting based on real world coordinates and modifying the lumens and so forth. Based on what I've read, the Python Dictionary concept flat will not work for such as this. Yes - the example is overkill. But in my world it is reality. I deal with sizeable things. Not all are raster. Most all are binary! Things that work on massive text files - like banking and mortgage - simply don't work here. There are seldom 'lines'. There are always bytes. Lots of bytes. Things that form a group are not necessarily stored sequentially. Back to What Is A Python Dictionary: Somebody please enlighten me. Steve [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
