Rearranging elements in Python - list

Question

i am new to Python and i cant get this.I have a List and i want to take the input from there and write those in files .
p = ['Eth1/1', 'Eth1/5','Eth2/1', 'Eth2/4','Eth101/1/1', 'Eth101/1/2', 'Eth101/1/3','Eth102/1/1', 'Eth102/1/2', 'Eth102/1/3','Eth103/1/1', 'Eth103/1/2', 'Eth103/1/3','Eth103/1/4','Eth104/1/1', 'Eth104/1/2', 'Eth104/1/3','Eth104/1/4']
What i am trying :
with open("abc1.txt", "w+") as fw1, open("abc2.txt", "w+") as fw2:
for i in p:
if len(i.partition("/")[0]) == 4:
fw1.write('int ' + i + '\n mode\n')
else:
i = 0
while i < len(p):
start = p[i].split('/')
if (start[0] == 'Eth101'):
i += 3
key = start[0]
i += 1
while i < len(p) and p[i].split('/')[0] == key:
i += 1
end = p[i-1].split('/')
fw2.write('confi ' + start[0] + '/' + start[1] + '-' + end[1] + '\n mode\n')
What i am looking for :
abc1.txt should have
int Eth1/1
mode
int Eth1/5
mode
int Eth2/1
mode
int Eth 2/4
mode
abc2.txt should have :
int Eth101/1/1-3
mode
int Eth102/1/1-3
mode
int Eth103/1/1-4
mode
int Eth104/1/1-4
mode
So any Eth having 1 digit before " / " ( e:g Eth1/1 or Eth2/2
)should be in one file that is abc1.txt .
Any Eth having 3 digit before " / " ( e:g Eth101/1/1 or Eth 102/1/1
) should be in another file that is abc2.txt and .As these are in
ranges , need to write it like Eth101/1/1-3, Eth102/1/1-3 etc
Any Idea ?

Answer 1

I don't think you need a regex here, at all. All your items begin with 'Eth' followed by one or more digits. So you can check the length of the items before first / occurs and then write it to a file.
p = ['Eth1/1', 'Eth1/5','Eth2/1', 'Eth2/4','Eth101/1/1', 'Eth101/1/2', 'Eth101/1/3','Eth102/1/1', 'Eth102/1/2', 'Eth102/1/3','Eth103/1/1', 'Eth103/1/2', 'Eth103/1/3','Eth103/1/4','Eth104/1/1', 'Eth104/1/2', 'Eth104/1/3','Eth104/1/4']
with open("abc1.txt", "w+") as fw1, open("abc2.txt", "w+") as fw2:
for i in p:
if len(i.partition("/")[0]) == 4:
fw1.write('int ' + i + '\n mode\n')
else:
fw2.write('int ' + i + '\n mode\n')
I refactored your code a little to bring with-statement into play. This will handle correctly closing the file at the end. Also it is not necessary to iterate twice over the sequence, so it's all done in one iteration.
If the data is not as clean as provided, then you maybe want to use regexes. Independent of the regex itself, by writing if re.match(r'((Eth\d{1}\/\d{1,2})', "p" ) you proof if a match object can be created for given regex on the string "p", not the value of the variable p. This is because you used " around p.
So this should work for your example. If you really need a regex, this will turn your problem in finding a good regex to match your needs without any other issues.
As these are in ranges , need to write it like Eth101/1/1-3, Eth102/1/1-3 etc
This is something you can achieve by first computing the string and then write it in the file. But this is more like a separate question.
UPDATE
It's not that trivial to compute the right network ranges. Here I can present you one approach which doesn't change my code but adds some functionality. The trick here is to get groups of connected networks which aren't interrupted by their numbers. For that I've copied consecutive_groups. You can also do a pip install more-itertools of course to get that functionality. And also I transformed the list to a dict to prepare the magic and then retransformed dict to list again. There are definitely better ways of doing it, but this worked for your input data, at least.
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from itertools import groupby
from operator import itemgetter
p = ['Eth1/1', 'Eth1/5', 'Eth2/1', 'Eth2/4', 'Eth101/1/1', 'Eth101/1/2',
'Eth101/1/3', 'Eth102/1/1', 'Eth102/1/2', 'Eth102/1/3', 'Eth103/1/1',
'Eth103/1/2', 'Eth103/1/3', 'Eth103/1/4', 'Eth104/1/1', 'Eth104/1/2',
'Eth104/1/3', 'Eth104/1/4']
def get_network_ranges(networks):
network_ranges = {}
result = []
for network in networks:
parts = network.rpartition("/")
network_ranges.setdefault(parts[0], []).append(int(parts[2]))
for network, ranges in network_ranges.items():
ranges.sort()
for group in consecutive_groups(ranges):
group = list(group)
if len(group) == 1:
result.append(network + "/" + str(group[0]))
else:
result.append(network + "/" + str(group[0]) + "-" +
str(group[-1]))
result.sort() # to get ordered results
return result
def consecutive_groups(iterable, ordering=lambda x: x):
"""taken from more-itertools (latest)"""
for k, g in groupby(
enumerate(iterable), key=lambda x: x[0] - ordering(x[1])
):
yield map(itemgetter(1), g)
# only one line added to do the magic
with open("abc1.txt", "w+") as fw1, open("abc2.txt", "w+") as fw2:
p = get_network_ranges(p)
for i in p:
if len(i.partition("/")[0]) == 4:
fw1.write('int ' + i + '\n mode\n')
else:
fw2.write('int ' + i + '\n mode\n')