Nested lists or conditional logic?

Joe Francia usenet at -OBFUSCATION-joefrancia.com
Wed Jan 28 19:41:34 CET 2004


mike beck wrote:
 > this is not all complex, but as a noob i'm having a hard time getting
 > my head around it.
 >
 > i have a list of items. i need to print the items in batches of x,
 > with a summary line after each complete or partial batch, and a total
 > line at the end of the job.
 >
 > if the list looks like ['line1','line2','line3'], and my ITEMSINBATCH
 > = 1, the output should look like this:
 >
 > line1
 > ---summary line---
 > line2
 > ---summary line---
 > line3
 > ---summary line---
 > ---total line---
 >
 > if ITEMSINBATCH = 2, the output should look like this:
 >
 > line1
 > line2
 > ---summary line---
 > line3
 > ---summary line---
 > ---total line---
 >
 > i've done the following, which works, but it seems like there must be
 > a better/simpler/faster way to do this with nested loops. ideas?
 >
 >
 > # ---------------------Begin code---------------------
 > ITEMSINBATCH = 1;
 > ARBITRARYNUM = 51;
 >
 > # create a list to work with
 > myList = ['1']*ARBITRARYNUM;
 >
 > for i in range( len(myList) ):
 >     # avoid starting at 0
 >     count = i + 1;
 >
 >     print "The item is:",myList[i],'\t',count;
 >
 >     # ensure that the batch summary line is printed every ITEMSINBATCH
 >     # times but not if the number of items is evenly divisible by
 >     # ITEMSINBATCH, in which case both the inner print and the outer
 >     # print would execute and we'd get consecutive batch summary lines
 >     if ( (count) % ITEMSINBATCH ) is 0 and count != len(myList)::
 >         print "-----Add batch summary line-----";
 >
 > # add a final batch line for those trailing items
 > print "------Add batch summary line------And BTW, i is", count;
 >
 > # and add the final summary line
 > print "------Add file summary------";
 >
 > # ---------------------End code---------------------


I'm not sure this is faster, but it sure is simpler:

mylist = range(23)
batchsize = 4

for i in range(0,len(mylist),batchsize):
     for l in mylist[i:i+batchsize]:
         print l
     print "---summary line---"
print "---file summary---"



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