Deleting lines from readlines()

Question

f = open('df.txt','r')
l = f.readlines()
for x in l:
    print(x)
    for n in l:
        if x == n:
            l.remove(n)

I want to create a list, print variables in order and delete same variables from the list if there are. Example: one two three one four 1- It must print "one", and delete [0] and [3] from the list.

but it skips variables when I run.

Answer 1

It's best not to change length of a list during iteration, so append what you want to a new list and skip what you don't

mylist = []
f = open('df.txt','r')
l = f.readlines()
for x in l:
    print(x)
    for n in l:
        if x != n:
            mylist.append(x)

Answer 2

recent versions of Python have a Dict implementation that retains its insertion order, so you could also write:

lines = 'one two three one four'.split(' ')

list(dict((l, None) for l in lines))

Output:

['one', 'two', 'three', 'four']