BilliAm
Reputation: 589
How to check next iter item without proceeding in For loop in Python
When iterating via next(iter) I am wanting to basically group together networks, I do this by calculating how many items appear in each line, if it has 7 items, it's the start of a entry.
I then look for lines beneath the entry line, until I find another line with 7 items. The process then starts over.
Only problem is when I'm access the "next line" via line = next(bgp_table_iter) and break the loop, if the "next line" has 7 items meaning start a new entry, when it starts back at for line in bgp_table_iter: it iterates again to the next line skipping the original "next line" that should have 7 items and is the start of a new entry.
Which end's up skipping every other entry.
How could I prevent a the skip? Or make the For loop trigger going to the previous iteration on break?
def show_ip_bgp():
data = test_output_short.split('RPKI validation codes: V valid, I invalid, N Not found\n\n Network Next Hop Metric LocPrf Weight Path\n')
bgp_table = data[1]
bgp_table = re.sub(" Network Next Hop Metric LocPrf Weight Path\n","",bgp_table)
bgp_table = re.sub("\*","",bgp_table)
bgp_table_list = bgp_table.split('\n')
bgp_table_iter = iter(bgp_table_list)
overall_dict = {}
index = 0
for line in bgp_table_iter:
# print line.split(), len(line.split())
current_line = line.split()
# If 7 items are in the list it's the start of a network
if len(current_line) == 7:
best = True if '>' in current_line[0] else False
network = current_line[1]
attached_ip = current_line[2]
print "Found Starting Network", network, attached_ip, "Best Path: {}".format(best)
for i in range(0,1000):
line = next(bgp_table_iter)
subline_line = line.split()
best_sub = 'True' if '>' in subline_line[0] else 'False'
if len(subline_line) == 6:
print 'Sub:', subline_line[1], "Best Path: {}".format(best_sub)
elif len(subline_line) == 5:
print 'Sub:', subline_line[1], "Best Path: {}".format(best_sub)
elif len(subline_line) == 7:
break
test_output_short = '''BGP table version is 3538854, local router ID is 10.15.1.81
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path
* i 10.0.1.0/24 10.8.111.45 0 115 0 i
*>i 10.8.11.45 0 120 0 i
* i 10.8.11.45 0 120 0 i
* i 10.8.11.45 0 120 0 i
* i 10.0.3.0/29 10.8.111.45 0 115 0 i
*>i 10.8.11.45 0 120 0 i
* i 10.8.11.45 0 120 0 i
* i 10.8.11.45 0 120 0 i
* i 10.8.0.0/16 10.9.0.1 0 50 0 i
* i 10.8.0.1 0 50 0 i
*> 0.0.0.0 0 32768 i
* i 10.9.0.0/16 10.9.0.1 0 50 0 i
* i 10.8.0.1 0 50 0 i
*> 0.0.0.0 0 32768 i
*>i 10.10.2.0/24 10.8.10.2 0 100 0 i
* i 10.8.10.2 0 100 0 i
* i 10.8.10.2 0 100 0 i
* i 10.10.5.0/24 10.8.142.15 0 85 0 i
*>i 10.8.42.15 0 100 0 i
* i 10.8.42.15 0 100 0 i
* i 10.8.42.15 0 100 0 i
*>i 10.10.7.0/24 10.8.40.84 0 100 0 i
* i 10.8.40.84 0 100 0 i
* i 10.8.40.84 0 100 0 i
*>i 10.10.8.0/24 10.8.10.8 0 100 0 i
* i 10.8.110.8 0 85 0 i
* i 10.8.10.8 0 100 0 i
* i 10.8.10.8 0 100 0 i
*>i 10.10.11.0/24 10.8.42.8 0 100 0 i
* i 10.8.42.8 0 100 0 i
* i 10.8.42.8 0 100 0 i
* i 10.9.42.8 0 100 0 i
* i 10.10.12.0/24 10.8.10.12 0 100 0 i
* i 10.8.10.12 0 100 0 i
*>i 10.8.10.12 0 100 0 i'''
Output:
>>> show_ip_bgp()
Found Starting Network 10.0.1.0/24 10.8.111.45 Best Path: False
Sub: 10.8.11.45 Best Path: True
Sub: 10.8.11.45 Best Path: False
Sub: 10.8.11.45 Best Path: False
Found Starting Network 10.8.0.0/16 10.9.0.1 Best Path: False
Sub: 10.8.0.1 Best Path: False
Sub: 0.0.0.0 Best Path: True
Found Starting Network 10.10.2.0/24 10.8.10.2 Best Path: True
Sub: 10.8.10.2 Best Path: False
Sub: 10.8.10.2 Best Path: False
Found Starting Network 10.10.7.0/24 10.8.40.84 Best Path: True
Sub: 10.8.40.84 Best Path: False
Sub: 10.8.40.84 Best Path: False
Found Starting Network 10.10.11.0/24 10.8.42.8 Best Path: True
Sub: 10.8.42.8 Best Path: False
Sub: 10.8.42.8 Best Path: False
Sub: 10.9.42.8 Best Path: False
UPDATE:
The suggested fix appeared to work until I ran tests. It does make all networks appear sort of.
def show_ip_bgp(): data = test_output_very_short.split('RPKI validation codes: V valid, I invalid, N Not found\n\n Network Next Hop Metric LocPrf Weight Path\n') bgp_table = data[1] bgp_table = re.sub(" Network Next Hop Metric LocPrf Weight Path\n","",bgp_table) bgp_table = re.sub("*","",bgp_table)
bgp_table_list = bgp_table.split('\n')
bgp_table_iter = iter(bgp_table_list)
overall_dict = {}
index = 0
for i, line in enumerate(bgp_table_list):
# print line.split(), len(line.split())
current_line = line.split()
# If 7 items are in the list it's the start of a network
if len(current_line) == 7:
best = True if '>' in current_line[0] else False
network = current_line[1]
attached_ip = current_line[2]
print "Found Starting Network", network, attached_ip, "Best Path: {}".format(best)
for i in range(0,1000):
line = bgp_table_list[i+1]
print i
subline_line = line.split()
best_sub = 'True' if '>' in subline_line[0] else 'False'
if len(subline_line) == 6:
print 'Sub:', subline_line[1], "Best Path: {}".format(best_sub)
elif len(subline_line) == 5:
print 'Sub:', subline_line[1], "Best Path: {}".format(best_sub)
elif len(subline_line) == 7:
line = bgp_table_list[i+1]
break
Output:
Found Entry Network: 10.0.1.0/24 Nexthop: 10.8.111.45 Best Path: False Pref: 115
0
Found Network: 10.0.1.0/24 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.0.1.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.0.1.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.0.3.0/29 Nexthop: 10.8.111.45 Best Path: False Pref: 115
0
Found Network: 10.0.3.0/29 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.0.3.0/29 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.0.3.0/29 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.8.0.0/16 Nexthop: 10.9.0.1 Best Path: False Pref: 50
0
Found Network: 10.8.0.0/16 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.8.0.0/16 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.8.0.0/16 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.9.0.0/16 Nexthop: 10.9.0.1 Best Path: False Pref: 50
0
Found Network: 10.9.0.0/16 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.9.0.0/16 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.9.0.0/16 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.10.2.0/24 Nexthop: 10.8.10.2 Best Path: True Pref: 100
0
Found Network: 10.10.2.0/24 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.10.2.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.10.2.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.10.5.0/24 Nexthop: 10.8.142.15 Best Path: False Pref: 85
0
Found Network: 10.10.5.0/24 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.10.5.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.10.5.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.10.7.0/24 Nexthop: 10.8.40.84 Best Path: True Pref: 100
0
Found Network: 10.10.7.0/24 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.10.7.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.10.7.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.10.8.0/24 Nexthop: 10.8.10.8 Best Path: True Pref: 100
0
Found Network: 10.10.8.0/24 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.10.8.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.10.8.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.10.11.0/24 Nexthop: 10.8.42.8 Best Path: True Pref: 100
0
Found Network: 10.10.11.0/24 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.10.11.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.10.11.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.10.12.0/24 Nexthop: 10.8.10.12 Best Path: False Pref: 100
0
Found Network: 10.10.12.0/24 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.10.12.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.10.12.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.10.15.0/24 Nexthop: 10.8.10.15 Best Path: False Pref: 100
0
Found Network: 10.10.15.0/24 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.10.15.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.10.15.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
Found Entry Network: 10.10.27.0/24 Nexthop: 10.8.41.81 Best Path: False Pref: 100
0
Found Network: 10.10.27.0/24 Nexthop: 10.8.11.45 Best Path: True Pref: 120
1
Found Network: 10.10.27.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
2
Found Network: 10.10.27.0/24 Nexthop: 10.8.11.45 Best Path: False Pref: 120
3
The index number is going back to 0 each time show here printing out the index of the line being checked.
Upvotes: 1
Views: 250
Answers (1)
CasualDemon
Reputation: 6160
Instead of forcing it to be an iter, keep using it as a list, then use enumerate to know your location in the list.
Edit: Chaning first enumerate to use index, the second loop's range to start with 1 instead of 0, and the line check to line = bgp_table_list[index+i] with an except clause for when it reaches end of file.
for index, line in enumerate(bgp_table_list):
# print line.split(), len(line.split())
current_line = line.split()
# If 7 items are in the list it's the start of a network
if len(current_line) == 7:
best = True if '>' in current_line[0] else False
network = current_line[1]
attached_ip = current_line[2]
print "Found Starting Network", network, attached_ip, "Best Path: {}".format(best)
for i in range(1, 1000):
try:
line = bgp_table_list[index+i]
except IndexError:
break
subline_line = line.split()
best_sub = 'True' if '>' in subline_line[0] else 'False'
if len(subline_line) == 6:
print 'Sub:', subline_line[1], "Best Path: {}".format(best_sub)
elif len(subline_line) == 5:
print 'Sub:', subline_line[1], "Best Path: {}".format(best_sub)
elif len(subline_line) == 7:
break
My output (not sure if correct, providing so you can judge)
Found Starting Network 10.0.1.0/24 10.8.111.45 Best Path: False
Sub: 10.8.11.45 Best Path: True
Sub: 10.8.11.45 Best Path: False
Sub: 10.8.11.45 Best Path: False
Found Starting Network 10.0.3.0/29 10.8.111.45 Best Path: False
Sub: 10.8.11.45 Best Path: True
Sub: 10.8.11.45 Best Path: False
Sub: 10.8.11.45 Best Path: False
Found Starting Network 10.8.0.0/16 10.9.0.1 Best Path: False
Sub: 10.8.0.1 Best Path: False
Sub: 0.0.0.0 Best Path: True
Found Starting Network 10.9.0.0/16 10.9.0.1 Best Path: False
Sub: 10.8.0.1 Best Path: False
Sub: 0.0.0.0 Best Path: True
Found Starting Network 10.10.2.0/24 10.8.10.2 Best Path: True
Sub: 10.8.10.2 Best Path: False
Sub: 10.8.10.2 Best Path: False
Found Starting Network 10.10.5.0/24 10.8.142.15 Best Path: False
Sub: 10.8.42.15 Best Path: True
Sub: 10.8.42.15 Best Path: False
Sub: 10.8.42.15 Best Path: False
Found Starting Network 10.10.7.0/24 10.8.40.84 Best Path: True
Sub: 10.8.40.84 Best Path: False
Sub: 10.8.40.84 Best Path: False
Found Starting Network 10.10.8.0/24 10.8.10.8 Best Path: True
Sub: 10.8.110.8 Best Path: False
Sub: 10.8.10.8 Best Path: False
Sub: 10.8.10.8 Best Path: False
Found Starting Network 10.10.11.0/24 10.8.42.8 Best Path: True
Sub: 10.8.42.8 Best Path: False
Sub: 10.8.42.8 Best Path: False
Sub: 10.9.42.8 Best Path: False
Found Starting Network 10.10.12.0/24 10.8.10.12 Best Path: False
Sub: 10.8.10.12 Best Path: False
Sub: 10.8.10.12 Best Path: True
Upvotes: 3
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