python while if 循环跳过代码行 (j += 1)

Question

I would really appreciate any help I can get.

I have 16x16 DataFrame 'DTA' (index - city of origin; columns - city of arrival) and number of flights made as values I have selected flights above certain value (20 in this example) and trying to make new DataFrame (column names 'Departure', 'Arrival' and 'Number of Flights') for those TOP X flights

I doing it through a while if loop (I have tried for loop as well, but keep failing) This looks close, but

here is the code first

n = 0
i = 0
j = 0
while n < len(DTA):
    while i < len(DTA):
        nfn = nf[arrival[n]]
        if i <= k:
            print(i)
            print(j)
            print(n)
            print(k)
            print(' ')
            df['Arrival'][i] = arrival[n]
            df['Number of Flights'][i] = nfn[j]
            i += 1
            j += 1
        else:
            n += 1
            j = 0

            k += len(nfn)

arrival - list of names (in order) of cities that the planes arrived at. nfn - shows cities of origin with flights exceeding X, like so

origin
Chicago      29.0
Miami        29.0
Naples       44.0
Phoenix      25.0
Teterboro    47.0

As you probably noticed I've put a lot of prints to keep track of my variables here is the result:

0
0
0
0
 
1
0
1
5
 
2
1
1
5
 
3
2
1
5
 
4
3
1
5

In my understanding it should increase both i and j by 1 each iteration before increasing n, but it skips over j and I have no idea why.

len(DTA) = 16
len(nfn[0]) = 5
len(nfn[1]) = 1

also loop doesn't stop, but 1 problem at the time. Would appreciate all and every input

Answer 1

If you would put prints in the else case you would probably find the mistake. Your condition tells "i<=k". k initially is zero. So you go into the if case where i is increased by one. Then in the next iteration you go into else and j is reset to zero.