[Tutor] dealing with lists (2)

[marcus.luetolf at bluewin.ch]

Sorry, I sent my following comment to the wrong address :

 

Yes, you are right. 

 

But but my final goal is to create 20 sublistst with item-pairs (16 items
total) appearing only once.

I found that my initial approach to which I postet questions a few days ago
lead to a dead end.

 

So I used a simpler way tro create those 20 sublists as posted more
recently.

 

I am still working on a way to change the sequence of items in those 20
sublists til the condition concerning the pairs of items is met.

 

I know that my goal is  mathematically possible with 16 items in 20 sublists
from a discussion a couple of years ago.

 

I refined my code below but with changing the indices of f1, f2, f3, f4 and
by n manually I'am unable to avoid double pairings.

I think I reached another dead end.

Bur mybe someone could give me an idea for a different approach before
giving up.

 

 

>comb_list = []

f>or dummy_i in range(4):  

    >copy_all_letters = all_letters[:]

    >lst = (16*16)*copy_all_letters

    >f1 = []

    >f2 = []

    >f3 = []

    >f4 = []

   > f1.append(lst[0+n])

    >f1.append(lst[2+n])

    >f1.append(lst[4+n])

    >f1.append(lst[6+n])

   > f1.sort()

    >comb_list.append(f1)

    >f2.append(lst[8+n])

    >f2.append(lst[10+n])

    >f2.append(lst[12+n])

    >f2.append(lst[14+n])

    >f2.sort()

    >comb_list.append(f2)

   > f3.append(lst[1+n])

    >f3.append(lst[3+n])

    >f3.append(lst[5+n])

    >f3.append(lst[7+n])

    >f3.sort()

    >comb_list.append(f3)

   > f4.append(lst[9+n])

    >f4.append(lst[11+n])

   > f4.append(lst[13+n])

   > f4.append(lst[15+n])

    >f4.sort()

   > comb_list.append(f4)

   > print(f1, f2, f4, f4)

   > print(comb_list)

   > n += 3

 

 

Hello Experts, 

I try to solve the following problem:

 

I'd like to create  5 lists, each containing 4 sublists : f1, f2, f3, f4,
f5, a total of 20 sublists.

I have a list (named all_letters) contaning 16 characters a, b, c, ...p.

 

I  would liketo  distribute all 16 characters to the 4 sublists 5 times in 5
iterations respectivly  so that

as a condition a pair of characters, p.e. ['a', 'b', .]  or ['a', 'c'.] or
[.'n', 'p'] can appear only once in all 20 sublists.

 

To find the sublists fullfilling this condition I designed the following
code with the intention to change the indices

defined by the variables n and p til the condition is met :

 

all_letters = list('abcdefghijklmnop')

f1 = []

f2 = []

f3 = []

f4 = []

n = 0

p = 1

for dummy_i in range(5):  

    copy_all_letters = all_letters[:]

    lst = 16*copy_all_letters

    f1.append(lst[n+0])

    f1.append(lst[n+p])

    f1.append(lst[n+2*p])

    f1.append(lst[n+3*p])

    f1.sort()

    f2.append(lst[n+4*p])

    f2.append(lst[n+5*p])

    f2.append(lst[n+6*p])

    f2.append(lst[n+7*p])

    f2.sort()

    f3.append(lst[n+8*p])

    f3.append(lst[n+9*p])

    f3.append(lst[n+10*p])

    f3.append(lst[n+11*p])

    f3.sort()

    f4.append(lst[n+12*p])

    f4.append(lst[n+13*p])

    f4.append(lst[n+14*p])

    f4.append(lst[n+15*p])

    f4.sort()

       

    print('f1: ', f1)

    print('f2: ', f2)

    print('f3: ', f3)

    print('f4: ', f4)

    n += 4

    p += 1

    f1 = []

    f2 = []

    f3 = []

    f4 = []

    f5 = []

 

But I'm unable to define the condition mentioned above and asking for your
help.