Re: [Tutor] Unique Items in Lists
Try a simple bubble sort. This will not have great performance on big files at a worst case scenario it will take n-1 loops to sort. This is not very general and would require a substantially different implementation. def bublesort(l1,l2,l3): modified=True while modified: modified=False for number,value in enumerate(l3): if number>0:#to avoid index error if l3[number]Dear Danny, thank you for ur help. But a basic >question ? > >In a table, more specifically a matrix 3X3, > >AppleFruitDenmark >F-16 Fighter USA >Taj Wonder India >MummyAntique Egypt > > >IF I have to sort on country, it should be > >AppleFruitDenmark >MummyAntique Egypt >Taj Wonder India >F-16 Fighter USA > > __ Do you Yahoo!? Yahoo! Mail - now with 250MB free storage. Learn more. http://info.mail.yahoo.com/mail_250 ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Unique Items in Lists
Srinivas,
You can't sort a string, since it's immutable. You can, however, sort
a list. To sort your table by the third element, you can do something
like this:
>>> table = (("apple", "fruit", "denmark"),
... ("mummy", "antique", "egypt"),
... ("taj", "wonder", "india"),
... ("f-16", "fighter", "usa"))
>>> sorter = [(elt[2], elt) for elt in table]
>>> sorter.sort()
>>> tuple([elt[1] for elt in sorter])
(('apple', 'fruit', 'denmark'),
('mummy', 'antique', 'egypt'),
('taj', 'wonder', 'india'),
('f-16', 'fighter', 'usa'))
# I edited the table output edited for clarity
When you sort a list of tuples, the default is to sort the list by the
first element in the tuples. If you make a list where the element you
want to sort on is first in all of the tuples (see the 'sorter = ...'
line), then sort that list, then remove the element you added (the
'tuple([...])' line), you are left with a list which is ordered the
way you want it.
Peace
Bill Mill
bill.mill at gmail.com
On Thu, 27 Jan 2005 08:29:10 -0800 (PST), Srinivas Iyyer
<[EMAIL PROTECTED]> wrote:
> Dear Danny, thank you for ur help. But a basic
> question ?
>
> In a table, more specifically a matrix 3X3,
>
> AppleFruitDenmark
> F-16 Fighter USA
> Taj Wonder India
> MummyAntique Egypt
>
> IF I have to sort on country, it should be
>
> AppleFruitDenmark
> MummyAntique Egypt
> Taj Wonder India
> F-16 Fighter USA
>
> How can I sort by binding Denmark to fruit and apple
> as a string. String does not support sort function.
> Sincerly I dont know how to sort to follow your
> suggestion. can you please help.. sorry for asking
> basic question.
>
> thank you
>
>
> --- Danny Yoo <[EMAIL PROTECTED]> wrote:
>
> >
> >
> > On Wed, 26 Jan 2005, Srinivas Iyyer wrote:
> >
> > > I have a list with 4 columns and column1 elements
> > are unique. I wanted
> > > to extract unique elements in column3 and and
> > place the other elements
> > > of the column along with unique elements in column
> > 4 as a tab delim
> > > text.
> > >
> > > Table:
> > >
> > > col1col2col3 col4
> > > A Apple 5Chennai
> > > B Baby 11Delhi
> > > I Baby* 1Delhi
> > > M Dasheri+ 5Mumbai
> > > K Apple 12 Copenhagen
> >
> >
> > [Meta: we seem to be getting a run of similar
> > questions this week. Scott
> > Melnyk also asked about grouping similar records
> > together:
> >
> http://mail.python.org/pipermail/tutor/2005-January/035185.html.]
> >
> >
> > Hi Srinivas,
> >
> > I see that you are trying to group records based on
> > some criterion. You
> > may find the problem easier to do if you fist do a
> > sort on that criterion
> > column: that will make related records "clump"
> > together.
> >
> >
> > For your sample data above, if we sort against the
> > second column, the
> > records will end up in the following order:
> >
> > ###
> > A Apple 5Chennai
> > K Apple 12 Copenhagen
> > B Baby 11 Delhi
> > I Baby 1Delhi
> > M Dasheri 5Mumbai
> > ###
> >
> >
> > In this sorting approach, you can then run through
> > the sorted list in
> > order. Since all the related elements should be
> > adjacent, grouping
> > related lines together should be much easier, and
> > you should be able to
> > produce the final output:
> >
> > ###
> > Apple A,K 5,12Chennai,Copenhagen
> > Baby B,I 1,11Delhi
> > Dasheri M 5 Mumbai
> > ###
> >
> > without too much trouble. You can do this problem
> > without dictionaries at
> > all, although you may find the dictionary approach a
> > little easier to
> > implement.
> >
> >
> >
> >
> > > A dictionary option does not work
> >
> > A dictionary approach is also very possible. The
> > thing you may be stuck
> > on is trying to make a key associate with multiple
> > values. Most examples
> > of dictionaries in tutorials use strings as both the
> > keys and values, but
> > dictionaries are more versatile: we can also make a
> > dictionary whose
> > values are lists.
> >
> >
> > For example, here is a small program that groups
> > words by their first
> > letters:
> >
> > ###
> > >>> def groupAlpha(words):
> > ... groups = {}
> > ... for w in words:
> > ... firstLetter = w[0]
> > ... if firstLetter not in groups:
> > ... groups[firstLetter] = []
> > ... groups[firstLetter].append(w)
> > ... return groups
> > ...
> > >>> groupAlpha("this is a test of the emergency
> > broadcast system".split())
> > {'a': ['a'],
> > 'b': ['broadcast'],
> > 'e': ['emergency'],
> > 'i': ['is'],
> > 'o': ['of'],
> > 's': ['system'],
> > 't': ['this', 'test', 'the']}
> > ###
> >
> >
> > If you have more questions, please feel free to ask.
> >
> >
>
> __
> Do you Yahoo!?
> Meet the all-new My Yahoo! - Try it today!
> http://my.yahoo.com
>
>
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Re: [Tutor] Unique Items in Lists
Dear Danny, thank you for ur help. But a basic
question ?
In a table, more specifically a matrix 3X3,
AppleFruitDenmark
F-16 Fighter USA
Taj Wonder India
MummyAntique Egypt
IF I have to sort on country, it should be
AppleFruitDenmark
MummyAntique Egypt
Taj Wonder India
F-16 Fighter USA
How can I sort by binding Denmark to fruit and apple
as a string. String does not support sort function.
Sincerly I dont know how to sort to follow your
suggestion. can you please help.. sorry for asking
basic question.
thank you
--- Danny Yoo <[EMAIL PROTECTED]> wrote:
>
>
> On Wed, 26 Jan 2005, Srinivas Iyyer wrote:
>
> > I have a list with 4 columns and column1 elements
> are unique. I wanted
> > to extract unique elements in column3 and and
> place the other elements
> > of the column along with unique elements in column
> 4 as a tab delim
> > text.
> >
> > Table:
> >
> > col1col2col3 col4
> > A Apple 5Chennai
> > B Baby 11Delhi
> > I Baby* 1Delhi
> > M Dasheri+ 5Mumbai
> > K Apple 12 Copenhagen
>
>
> [Meta: we seem to be getting a run of similar
> questions this week. Scott
> Melnyk also asked about grouping similar records
> together:
>
http://mail.python.org/pipermail/tutor/2005-January/035185.html.]
>
>
> Hi Srinivas,
>
> I see that you are trying to group records based on
> some criterion. You
> may find the problem easier to do if you fist do a
> sort on that criterion
> column: that will make related records "clump"
> together.
>
>
> For your sample data above, if we sort against the
> second column, the
> records will end up in the following order:
>
> ###
> A Apple 5Chennai
> K Apple 12 Copenhagen
> B Baby 11 Delhi
> I Baby 1Delhi
> M Dasheri 5Mumbai
> ###
>
>
> In this sorting approach, you can then run through
> the sorted list in
> order. Since all the related elements should be
> adjacent, grouping
> related lines together should be much easier, and
> you should be able to
> produce the final output:
>
> ###
> Apple A,K 5,12Chennai,Copenhagen
> Baby B,I 1,11Delhi
> Dasheri M 5 Mumbai
> ###
>
> without too much trouble. You can do this problem
> without dictionaries at
> all, although you may find the dictionary approach a
> little easier to
> implement.
>
>
>
>
> > A dictionary option does not work
>
> A dictionary approach is also very possible. The
> thing you may be stuck
> on is trying to make a key associate with multiple
> values. Most examples
> of dictionaries in tutorials use strings as both the
> keys and values, but
> dictionaries are more versatile: we can also make a
> dictionary whose
> values are lists.
>
>
> For example, here is a small program that groups
> words by their first
> letters:
>
> ###
> >>> def groupAlpha(words):
> ... groups = {}
> ... for w in words:
> ... firstLetter = w[0]
> ... if firstLetter not in groups:
> ... groups[firstLetter] = []
> ... groups[firstLetter].append(w)
> ... return groups
> ...
> >>> groupAlpha("this is a test of the emergency
> broadcast system".split())
> {'a': ['a'],
> 'b': ['broadcast'],
> 'e': ['emergency'],
> 'i': ['is'],
> 'o': ['of'],
> 's': ['system'],
> 't': ['this', 'test', 'the']}
> ###
>
>
> If you have more questions, please feel free to ask.
>
>
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Re: [Tutor] Unique Items in Lists
> for i in range(len(a)): > for k in range(len(a)): for k in range(i,len(a)): is faster, and if you calculate len before starting the loops that will speed it up too. (You calculate len for each iteration of each loop!) > if i != k: > if a[i] == a[k]: > print a[i] > break HTH Alan G. ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Unique Items in Lists
Srinivas Iyyer said unto the world upon 2005-01-27 01:17:
Dear Jacob, thank you for your suggestion.
however, i think my question was not clear. what i
meant to ask in my previous question was, how to know
which elements repeated and how many times they were
repeated.
while my question was flying, i did a small test:
took a list:
a
[1, 1, 2, 3, 4, 2, 2]
wanted to know which elements repeated and how many
times:
for i in range(len(a)):
for k in range(len(a)):
if i != k:
if a[i] == a[k]:
print a[i]
break
In this very huge list (:-) kidding) of 7 elements, it
is easy know by the above primitive code that there 1
s repeated two times, and 2 s repeated three times and
finally 1 and 2 numbers are repeated in list a:
With sets option i get a list of unique elements, but
by no means i get to know which elements were repeated
and how many times. With the above primitive code , I
know that 1 and 2 are peated. However, in case where
there are thousands of entries, how can I get to kno
wich elements got repeated and how many times.
Do you see any flaws in this code, how can that be
made to look more pyhonian way.
Hope my question is clear now and appreciate your
suggestions.
Thank you in advance
Srini
Hi Srini,
for the task of finding out which items are repeated and how many
times, I'd do this:
def dups_in_list_report(a_list):
'''Prints a duplication report for a list.'''
items_dict = {}
for i in a_list:
if i in items_dict:
items_dict[i] = items_dict[i] + 1
else:
items_dict[i] = 1
for key in items_dict.copy(): # Try it without the .copy()
if items_dict[key] == 1:# and see what happens.
del items_dict[key]
dict_keys = items_dict.keys()
dict_keys.sort()
for key in dict_keys:
print '%s occurred %s times' %(key, items_dict[key])
f = [1,1,2,3,3,3,3,4,4,4,4,4,4,4,5]
dups_in_list_report(f)
And, now that I get back on-line, I see that Chad posted the same
basic idea. But, perhaps the extra stuff here is of use, too.
HTH,
Brian vdB
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Re: [Tutor] Unique Items in Lists
Ok. I think I understand and I happen to be up at 1:30 my time so
here
is the solution as I understand the problem. This is a very common
problem and has a fairly easy solution. You can then take
adict.keys()
which returns a list of unique elements. Good Luck
import random
l=[random.randrange(1,20) for x in range(100)]
l
[7, 18, 17, 17, 6, 11, 14, 9, 4, 16, 2, 9, 3, 13, 4, 2, 5, 15, 15, 3,
3,
11, 18, 12, 6, 8, 15, 3, 7, 9, 9, 7, 12, 11, 11, 9, 19, 19, 15, 2,
17,
18, 16, 8, 15, 3, 19, 19, 19, 1, 3, 17, 3, 8, 16, 1, 5, 19, 17, 16,
19,
6, 3, 8, 16, 11, 12, 7, 10, 13, 13, 11, 6, 2, 18, 15, 17, 8, 12, 13,
5,
12, 2, 19, 2, 19, 7, 10, 4, 14, 15, 14, 5, 1, 16, 1, 9, 10, 17, 12]
adict={}
for x in l:
if adict.has_key(x):
#then there is already an item
adict[x]+=1 #increment the count by one
else: #there is no key the item hasn't been seen
adict[x]=1 #there is one instance so far
adict
{1: 4, 2: 6, 3: 8, 4: 3, 5: 4, 6: 4, 7: 5, 8: 5, 9: 6, 10: 3, 11: 6,
12:
6, 13: 4, 14: 3, 15: 7, 16: 6, 17: 7, 18: 4, 19: 9}
Srinivas Iyyer wrote:
>Dear Jacob, thank you for your suggestion.
>
>however, i think my question was not clear. what i
>meant to ask in my previous question was, how to know
>which elements repeated and how many times they were
>repeated.
>
>while my question was flying, i did a small test:
>
>took a list:
>
>
a
>[1, 1, 2, 3, 4, 2, 2]
>
>wanted to know which elements repeated and how many
>times:
>
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Re: [Tutor] Unique Items in Lists
Dear Jacob, thank you for your suggestion. however, i think my question was not clear. what i meant to ask in my previous question was, how to know which elements repeated and how many times they were repeated. while my question was flying, i did a small test: took a list: >>> a [1, 1, 2, 3, 4, 2, 2] wanted to know which elements repeated and how many times: for i in range(len(a)): for k in range(len(a)): if i != k: if a[i] == a[k]: print a[i] break 1 1 2 2 2 In this very huge list (:-) kidding) of 7 elements, it is easy know by the above primitive code that there 1 s repeated two times, and 2 s repeated three times and finally 1 and 2 numbers are repeated in list a: With sets option i get a list of unique elements, but by no means i get to know which elements were repeated and how many times. With the above primitive code , I know that 1 and 2 are peated. However, in case where there are thousands of entries, how can I get to kno wich elements got repeated and how many times. Do you see any flaws in this code, how can that be made to look more pyhonian way. Hope my question is clear now and appreciate your suggestions. Thank you in advance Srini > >>> import sets > >>> a = sets.Set([1,2,1,4,3,5,5,2,3,3,2]) > >>> a > Set([1, 2, 3, 4, 5]) > >>> list(a) ## This is one of the uses of the > builtin list -- to make a > >>> list of an iterable. > [1, 2, 3, 4, 5] > >>> > > HTH, > Jacob > > > This isnt working either. logic appears correct. > > looking forward for help pleas. > > > > thank you > > > > Srini > > > > > > > > > > > > > > __ > > Do you Yahoo!? > > The all-new My Yahoo! - What will yours do? > > http://my.yahoo.com > > ___ > > Tutor maillist - Tutor@python.org > > http://mail.python.org/mailman/listinfo/tutor > > > > > > __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Unique Items in Lists
col2_set = sets.Set(col2) how can I get a uniq elements that repeated several times: for item in range(len(list)): for k in range(len(list)): if item == k: if list[item] != k[list]: print item First off, this would never work. You are iterating over the same list so go through each step on paper or in your head. Oh, and don't use list for a variable name--it's a builtin function that you don't want to write over. An example a = [1,1,4,2,3,1,5] for item in range(len(a)): for k in range(len(a)): if item == k: if a[item]!=a[k]: ## I think this is what you meant to put--otherwise you would be trying to index an index! print item ## This returns an index, maybe you want the element instead? Ok... here's how it runs with all the variables replaced with the values defined by the loop. if 0 == 0: if 1!=1: print 1 That is okay. if 0 == 1: if 1 != 1: ## The first 1 comes from a[0] (item=0), the second 1 from a[1] (k=1) print 1 ## This is obviously not what you want, so immediately we see a problem. Then it goes through (0,2),(0,3),..(1,0),(1,1)(1,2),(2,0),(2,1), Anyway, this is all irrevelant because sets takes care of doubles. import sets a = sets.Set([1,2,1,4,3,5,5,2,3,3,2]) a Set([1, 2, 3, 4, 5]) list(a) ## This is one of the uses of the builtin list -- to make a list of an iterable. [1, 2, 3, 4, 5] HTH, Jacob This isnt working either. logic appears correct. looking forward for help pleas. thank you Srini __ Do you Yahoo!? The all-new My Yahoo! - What will yours do? http://my.yahoo.com ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Unique Items in Lists
On Wed, 26 Jan 2005, Srinivas Iyyer wrote:
> I have a list with 4 columns and column1 elements are unique. I wanted
> to extract unique elements in column3 and and place the other elements
> of the column along with unique elements in column 4 as a tab delim
> text.
>
> Table:
>
> col1col2col3 col4
> A Apple 5Chennai
> B Baby 11Delhi
> I Baby* 1Delhi
> M Dasheri+ 5Mumbai
> K Apple 12 Copenhagen
[Meta: we seem to be getting a run of similar questions this week. Scott
Melnyk also asked about grouping similar records together:
http://mail.python.org/pipermail/tutor/2005-January/035185.html.]
Hi Srinivas,
I see that you are trying to group records based on some criterion. You
may find the problem easier to do if you fist do a sort on that criterion
column: that will make related records "clump" together.
For your sample data above, if we sort against the second column, the
records will end up in the following order:
###
A Apple 5Chennai
K Apple 12 Copenhagen
B Baby 11 Delhi
I Baby 1Delhi
M Dasheri 5Mumbai
###
In this sorting approach, you can then run through the sorted list in
order. Since all the related elements should be adjacent, grouping
related lines together should be much easier, and you should be able to
produce the final output:
###
Apple A,K 5,12Chennai,Copenhagen
Baby B,I 1,11Delhi
Dasheri M 5 Mumbai
###
without too much trouble. You can do this problem without dictionaries at
all, although you may find the dictionary approach a little easier to
implement.
> A dictionary option does not work
A dictionary approach is also very possible. The thing you may be stuck
on is trying to make a key associate with multiple values. Most examples
of dictionaries in tutorials use strings as both the keys and values, but
dictionaries are more versatile: we can also make a dictionary whose
values are lists.
For example, here is a small program that groups words by their first
letters:
###
>>> def groupAlpha(words):
... groups = {}
... for w in words:
... firstLetter = w[0]
... if firstLetter not in groups:
... groups[firstLetter] = []
... groups[firstLetter].append(w)
... return groups
...
>>> groupAlpha("this is a test of the emergency broadcast system".split())
{'a': ['a'],
'b': ['broadcast'],
'e': ['emergency'],
'i': ['is'],
'o': ['of'],
's': ['system'],
't': ['this', 'test', 'the']}
###
If you have more questions, please feel free to ask.
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[Tutor] Unique Items in Lists
Hi,
I am a new member to this group and relatively to
python.
I have a list with 4 columns and column1 elements are
unique. I wanted to extract unique elements in
column3 and and place the other elements of the column
along with unique elements in column 4 as a tab delim
text.
Table:
col1col2col3 col4
A Apple 5Chennai
B Baby 11Delhi
I Baby* 1Delhi
M Dasheri+ 5Mumbai
K Apple 12 Copenhagen
* -> Baby => Infant + -> Dasheri => Mango
for ele in table:
col2 = ele.split('\t')[1]
col2.append(col2)
col2_set = sets.Set(col2)
col2_set -> (Apple,Baby Dasheri)
Apple A,K 5,12Chennai, Copenhagen
Baby B,I 1,11Delhi
Dasheri M 5 Mumbai.
for ele in col1_set:
nam = ele.strip()
for k in list:
m = re.search(nam,k)
cols = k.split('\t')
a = cols[0]
n = cols[2]
c = cols[3]
print nam+'\t'+a+'\t'+n+'\t'+c
A dictionary option does not work beca
This isnt working properly.
please help me any one
question 2:
A list with 100 unique items, repeated several times.
Apples - repeated 1000 times in list
Vegie - repeated 300 times in list
how can I get a uniq elements that repeated several
times:
for item in range(len(list)):
for k in range(len(list)):
if item == k:
if list[item] != k[list]:
print item
This isnt working either. logic appears correct.
looking forward for help pleas.
thank you
Srini
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