Is there an easier way to express this list slicing?

[John Henry]

If I have a list of say, 10 elements and I need to slice it into
irregular size list, I would have to create a bunch of temporary
variables and then regroup them afterwords, like:

# Just for illustration. Alist can be any existing 10 element list
a_list=("",)*10
(a,b,c1,c2,c3,d 1,d2,d3,d4,d5)= a_list
alist=(a,)
blist=(b,)
clist=(c1,c2,c3 )
dlist=(d2,d3,d4 ,d5)

That obviously work but do I *really* have to do that?

BTW: I know you can do:
alist=a_list[0]
blist=a_list[1]
clist=a_list[2:5]
dlist=a_list[5:]

but I don't see that it's any better.

Can I say something to the effect of:

(a,b,c[0:2],d[0:5])=a_list # Obviously this won't work

??

I am asking this because I have a section of code that contains *lots*
of things like this. It makes the code very unreadable.

Thanks,

[John Henry]

Paul McGuire wrote:

"Paul McGuire" <pt***@austin.r r._bogus_.comwr ote in message
news:Mm******** **********@torn ado.texas.rr.co m...

"John Henry" <jo**********@h otmail.comwrote in message
news:11******** *************@7 9g2000cws.googl egroups.com...

snip

Grrrr... that's what I get for not keeping editor and interpreter windows in
sync. My post was referencing vars I had defined in the interpreter, but
which the function had no clue of. !!! Here's a working version.

-- Paul
def splitUp(src,len s):
ret = []
cur = 0
for length in lens:
if length is not None:
ret.append( src[cur:cur+length] )
cur += length
else:
ret.append( src[cur:] )
return ret

origlist = list("ABCDEFGHI J")
alist, blist, clist, dlist = splitUp( origlist, (1,1,3,None) )
print alist, blist, clist, dlist

Nice.

While we are at it, why not:

class splitUp(object) :
def __init__(self,s rc):
self._src=list( src)
def slice(self, lens):
ret = []
cur = 0
for length in lens:
if length is not None:
ret.append( self._src[cur:cur+length] )
cur += length
else:
ret.append( self._src[cur:] )
return ret

alist, blist, clist, dlist = splitUp("ABCDEF GHIJ").slice((1 ,1,3,None))
print alist, blist, clist, dlist

Now, that's readable!

[John Henry]

John Henry wrote:

Paul McGuire wrote:

"Paul McGuire" <pt***@austin.r r._bogus_.comwr ote in message
news:Mm******** **********@torn ado.texas.rr.co m...

"John Henry" <jo**********@h otmail.comwrote in message
news:11******** *************@7 9g2000cws.googl egroups.com...

snip

Grrrr... that's what I get for not keeping editor and interpreter windows in
sync. My post was referencing vars I had defined in the interpreter, but
which the function had no clue of. !!! Here's a working version.

-- Paul
def splitUp(src,len s):
ret = []
cur = 0
for length in lens:
if length is not None:
ret.append( src[cur:cur+length] )
cur += length
else:
ret.append( src[cur:] )
return ret

origlist = list("ABCDEFGHI J")
alist, blist, clist, dlist = splitUp( origlist, (1,1,3,None) )
print alist, blist, clist, dlist

Nice.

While we are at it, why not:

class splitUp(object) :
def __init__(self,s rc):
self._src=list( src)
def slice(self, lens):
ret = []
cur = 0
for length in lens:
if length is not None:
ret.append( self._src[cur:cur+length] )
cur += length
else:
ret.append( self._src[cur:] )
return ret

alist, blist, clist, dlist = splitUp("ABCDEF GHIJ").slice((1 ,1,3,None))
print alist, blist, clist, dlist

Now, that's readable!

Further, if splitUp is a sub-class of string, then I can do:

alist, blist, clist, dlist = "ABCDEFGHIJ".sl ice((1,1,3,None ))

Now, can I override the slice operator?

[Thomas Ploch]

John Henry schrieb:

If I have a list of say, 10 elements and I need to slice it into
irregular size list, I would have to create a bunch of temporary
variables and then regroup them afterwords, like:

# Just for illustration. Alist can be any existing 10 element list
a_list=("",)*10
(a,b,c1,c2,c3,d 1,d2,d3,d4,d5)= a_list
alist=(a,)
blist=(b,)
clist=(c1,c2,c3 )
dlist=(d2,d3,d4 ,d5)

That obviously work but do I *really* have to do that?

BTW: I know you can do:
alist=a_list[0]
blist=a_list[1]
clist=a_list[2:5]
dlist=a_list[5:]

but I don't see that it's any better.

Can I say something to the effect of:

(a,b,c[0:2],d[0:5])=a_list # Obviously this won't work

??

I am asking this because I have a section of code that contains *lots*
of things like this. It makes the code very unreadable.

Thanks,

I had a little bit of fun while writing this:

itemList = (a,b,c1,c2,c3,d 1,d2,d3,d4,d5) and
itemList2 = (a1,a2,a3,b,c,d 1,d2,d3,d4,d5) the next time.

def getSlices(aCoun t, bCount, cCount, dCount, items):
a,b,c,d = (items[0:aCount],
items[aCount:aCount+b Count],
items[aCount+bCount:a Count+bCount+cC ount],
item[aCount+bCount+c Count:aCount+bC ount+cCount+dCo unt])
return list(a),list(b) ,list(c),list(d )

>>>a,b,c,d = getSlices(1,1,3 ,5,itemList)
print a,b,c,d

['a'] ['b'] ['c1', 'c2', 'c3'] ['d1', 'd2', 'd3', 'd4', 'd5']

>>>a,b,c,d = getSlices(3,1,1 ,0,itemList2)
print a,b,c,d

['a1', 'a2', 'a3'] ['b'] ['c'] []

%-)

Thomas

[John Henry]

John Henry wrote:

>
Further, if splitUp is a sub-class of string, then I can do:

alist, blist, clist, dlist = "ABCDEFGHIJ".sl ice((1,1,3,None ))

Now, can I override the slice operator?

Maybe like:

alist, blist, clist, dlist = newStr("ABCDEFG HIJ")[1,1,3,None]

where newStr is a sub-class of str, with a __repr__ that takes a
variable list of arguments?

(No clue how to code that yet, still pretty new to this)

Maybe they should make this a standard slicing feature....

[John Henry]

Thomas Ploch wrote:
<snip>

>
I had a little bit of fun while writing this:

itemList = (a,b,c1,c2,c3,d 1,d2,d3,d4,d5) and
itemList2 = (a1,a2,a3,b,c,d 1,d2,d3,d4,d5) the next time.

Huh? What's a,b,....d5?

def getSlices(aCoun t, bCount, cCount, dCount, items):
a,b,c,d = (items[0:aCount],
items[aCount:aCount+b Count],
items[aCount+bCount:a Count+bCount+cC ount],
item[aCount+bCount+c Count:aCount+bC ount+cCount+dCo unt])

You meant "items" here, right?

return list(a),list(b) ,list(c),list(d )

>>a,b,c,d = getSlices(1,1,3 ,5,itemList)
print a,b,c,d

['a'] ['b'] ['c1', 'c2', 'c3'] ['d1', 'd2', 'd3', 'd4', 'd5']

>>a,b,c,d = getSlices(3,1,1 ,0,itemList2)
print a,b,c,d

['a1', 'a2', 'a3'] ['b'] ['c'] []

%-)

Thomas

[Thomas Ploch]

John Henry schrieb:

Thomas Ploch wrote:
<snip>

>I had a little bit of fun while writing this:

itemList = (a,b,c1,c2,c3,d 1,d2,d3,d4,d5) and
itemList2 = (a1,a2,a3,b,c,d 1,d2,d3,d4,d5) the next time.

Huh? What's a,b,....d5?

John Henry schrieb:

Thomas Ploch wrote:
<snip>

>I had a little bit of fun while writing this:

itemList = (a,b,c1,c2,c3,d 1,d2,d3,d4,d5) and
itemList2 = (a1,a2,a3,b,c,d 1,d2,d3,d4,d5) the next time.

Huh? What's a,b,....d5?

Can be any object, as you had in your example in your mail:

>>>If I have a list of say, 10 elements and I need to slice it into
irregular size list, I would have to create a bunch of temporary
variables and then regroup them afterwords, like:

# Just for illustration. Alist can be any existing 10 element list
a_list=("",)* 10
(a,b,c1,c2,c3 ,d1,d2,d3,d4,d5 )=a_list
alist=(a,)
blist=(b,)
clist=(c1,c2, c3)
dlist=(d2,d3, d4,d5)

>def getSlices(aCoun t, bCount, cCount, dCount, items):
a,b,c,d = (items[0:aCount],
items[aCount:aCount+b Count],
items[aCount+bCount:a Count+bCount+cC ount],
item[aCount+bCount+c Count:aCount+bC ount+cCount+dCo unt])

You meant "items" here, right?

> return list(a),list(b) ,list(c),list(d )

>>>>a,b,c,d = getSlices(1,1,3 ,5,itemList)
print a,b,c,d

['a'] ['b'] ['c1', 'c2', 'c3'] ['d1', 'd2', 'd3', 'd4', 'd5']

>>>>a,b,c,d = getSlices(3,1,1 ,0,itemList2)
print a,b,c,d

['a1', 'a2', 'a3'] ['b'] ['c'] []

%-)

Thomas

[John Henry]

Thomas Ploch wrote:

>
John Henry schrieb:

Thomas Ploch wrote:
<snip>
I had a little bit of fun while writing this:

itemList = (a,b,c1,c2,c3,d 1,d2,d3,d4,d5) and
itemList2 = (a1,a2,a3,b,c,d 1,d2,d3,d4,d5) the next time.

>
Huh? What's a,b,....d5?
>

Can be any object, as you had in your example in your mail:

Oh, sorry.

[Paul McGuire]

"John Henry" <jo**********@h otmail.comwrote in message
news:11******** **************@ j72g2000cwa.goo glegroups.com.. .

>
John Henry wrote:

>>
Further, if splitUp is a sub-class of string, then I can do:

alist, blist, clist, dlist = "ABCDEFGHIJ".sl ice((1,1,3,None ))

Now, can I override the slice operator?

Maybe like:

alist, blist, clist, dlist = newStr("ABCDEFG HIJ")[1,1,3,None]

No need to contort string, just expand on your earlier idea. I changed your
class name to SplitUp to more more conventional (class names are usually
capitalized), and changed slice to __call__. Then I changed the lens arg to
*lens - note the difference in the calling format. Pretty close to what you
have above. Also, reconsider whether you want the __init__ function
list-ifying the input src - let the caller decide what to send in.

-- Paul

class SplitUp(object) :
def __init__(self,s rc):
self._src=list( src)
def __call__(self, *lens):
ret = []
cur = 0
for length in lens:
if length is not None:
ret.append( self._src[cur:cur+length] )
cur += length
else:
ret.append( self._src[cur:] )
return ret

alist, blist, clist, dlist = SplitUp("ABCDEF GHIJ")(1,1,3,No ne)
print alist, blist, clist, dlist

Prints:
['A'] ['B'] ['C', 'D', 'E'] ['F', 'G', 'H', 'I', 'J']

[John Henry]

Paul McGuire wrote:

"John Henry" <jo**********@h otmail.comwrote in message
news:11******** **************@ j72g2000cwa.goo glegroups.com.. .

John Henry wrote:

>
Further, if splitUp is a sub-class of string, then I can do:

alist, blist, clist, dlist = "ABCDEFGHIJ".sl ice((1,1,3,None ))

Now, can I override the slice operator?

Maybe like:

alist, blist, clist, dlist = newStr("ABCDEFG HIJ")[1,1,3,None]

No need to contort string, just expand on your earlier idea. I changed your
class name to SplitUp to more more conventional (class names are usually
capitalized), and changed slice to __call__. Then I changed the lens arg to
*lens - note the difference in the calling format. Pretty close to what you
have above. Also, reconsider whether you want the __init__ function
list-ifying the input src - let the caller decide what to send in.

In fact, should be possible to make that any object the caller want to
send in...

-- Paul

class SplitUp(object) :
def __init__(self,s rc):
self._src=list( src)
def __call__(self, *lens):
ret = []
cur = 0
for length in lens:
if length is not None:
ret.append( self._src[cur:cur+length] )
cur += length
else:
ret.append( self._src[cur:] )
return ret

alist, blist, clist, dlist = SplitUp("ABCDEF GHIJ")(1,1,3,No ne)
print alist, blist, clist, dlist

Prints:
['A'] ['B'] ['C', 'D', 'E'] ['F', 'G', 'H', 'I', 'J']

Thanks for the help,