CODEWITHSUNDEEP
python
JackNewman
JackNewman

Reputation: 55

How start second for loop at + 1 every iteration?

I have two for loops like

jj = 0

for ii in range(filename_list.__len__()):
    jj += 1
    for jj in range(filename_list.__len__()):
        if ii != jj:
            print(str(ii) + " " + str(jj) + "\n")

    print("=" * 5)

every time the ii for loop fully executes I want the next jj for loop to execute starting at the index +1 of what it was before.

currently, the output looks like

0 1
0 2
=====
1 0
1 2
=====
2 0
2 1
=====

but it should look more like

0 1
0 2
=====
1 2

thus for every iteration of the ii for loop there should be one less iteration for the jj loop.

Upvotes: 2

Views: 234

Answers (4)

shayelk
shayelk

Reputation: 1656

while J+=1 does increment j, the new value is ignored, as in the next line you're telling Python to start j at zero (range(x) is a range starting at x and ending at x-1)

How about:

for ii in range(filename_list.__len__()):
    for jj in range(ii + 1, filename_list.__len__()):
        if ii != jj:
            print(str(ii) + " " + str(jj) + "\n")

Upvotes: 0

kederrac
kederrac

Reputation: 17322

the inner for loop you could start from ii, since ii it is incremented with 1 after each loop of the inner for:

for ii in range(filename_list.__len__()):
    for jj in range(ii, filename_list.__len__()):
        if ii != jj:
            print(str(ii) + " " + str(jj) + "\n")

    print("=" * 5)

output: 

0 1

0 2

=====
1 2

Upvotes: 0

theo123490
theo123490

Reputation: 58

you can insert the starting point in the second range like below:

jj = 0
n=3

for ii in range(n):
    jj += 1
    for jj in range(ii,n):
        if ii != jj:
            print(str(ii) + " " + str(jj) + "\n")

    print("=" * 5)

I change the filename_list.__len__() into n

you can see I add the ii in the second range that means start the jj from ii, not from zero

Upvotes: 0

A.A.
A.A.

Reputation: 1047

You're also changing jj in your inner loop's iteration. Try this:

jj = 0

for ii in range(filename_list.__len__()):
    for jj in range(ii+1, filename_list.__len__()):
        print(str(ii) + " " + str(jj) + "\n")

    print("=" * 5)

Upvotes: 2

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