First, just a little rant :-)
It doesn't help to randomly change some lines or introduce some new
concepts you don't understand yet and then hope to get the right result.
Your chances are very small that this will be succesful.
You should try to understand some basic concepts first and build on them.
From your postings the last weeks and especially from today I have the
impression that you still don't understand how fundamental programming
concepts work: for-loops, differences between data types (strings,
lists, sets, ...)
Honestly, have you already read any programming tutorial? (You'll find a
big list at http://wiki.python.org/moin/BeginnersGuide/NonProgrammers )?
At the moment it looks like you are just copying some code snippets from
different places and then you hopelessly try to modify them to suit your
needs. IMHO the problems you want to solve are a little too big for you
right now.
Nevertheless, here are some comments:
Based on former advice, I made a correction/modification on the below code.
1] the set and subgroup does not work, here I wish to put all the
subgroup in a big set, the set like
That's a good idea, but you don't use the set correctly.
> subgroups=[]
> subgroup=[]
> def LongestCommonSubstring(S1, S2):
I think it's better to move "subgroups" and "subgroup" into the
function. (I've noticed that in most of your scripts you are using a lot
of global variables. IMHO that's not the best programming style. Do you
know what "global/local variables", "namespace", "scope" mean?)
You are defining "subgroups" as an empty list, but later you want to use
it as a set. Thus, you should define it as an empty set:
subgroups = set()
You are also defining "subgroup" as an empty list, but later you assign
a slice of "S1" to it. Since "S1" is a string, the slice is also a
string. Therefore:
subgroup = ""
> M = [[0]*(1+len(S2)) for i in xrange(1+len(S1))]
Peter told you already why "xrange" doesn't work in Python 3. But
instead of using an alias like
xrange = range
IMHO it's better to change it in the code directly.
> longest, x_longest = 0, 0
> for x in xrange(1,1+len(S1)):
> for y in xrange(1,1+len(S2)):
> if S1[x-1] == S2[y-1]:
> M[x][y] = M[x-1][y-1]+1
> if M[x][y]> longest:
> longest = M[x][y]
> x_longest = x
> if longest>= 3:
> subgroup=S1[x_longest-longest:x_longest]
> subgroups=set([subgroup])
Here you overwrite in the first iteration your original empty list
"subgroups" with the set of the list which contains the string
"subgroup" as its only element. Do you really understand this line?
And in all the following iterations you are overwriting this one-element
set with another one-element set (the next "subgroup").
If you want to add an element to an existing set instead of replacing
it, you have to use the "add()"-method for adding an element to a set:
subgroups.add(subgroup)
This will add the string "subgroup" as a new element to the set "subgroups".
> print(subgroups)
> else:
> M[x][y] = 0
>
> return S1[x_longest-longest:x_longest]
Here you probably want to return the set "subgroups":
return subgroups
2] I still have trouble in reading files, mainly about not read "" etc.
The problem is that in your data files there is just this big one-line
string. AFAIK you have produced these data files yourself, haven't you?
In that case it would be better to change the way how you save the data
(be it a well-formatted string or a list or something else) instead of
trying to fix it here (in this script).
Bye, Andreas
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