Can't compare variables from two dictionaries in Python

Question

I have two dictionaries and I want to compare their values srvuuid in hosts dictionary and srvuuidorg in backup dictionary.

This is hosts:

hosts = {}
for d in data['servers']['server']:
    srvhostname = d['hostname']
    srvuuid = d['uuid']
    hosts[srvhostname] = srvuuid

This is backup:

backup = {}
for u in backup_list['storages']['storage']:
    srvuuidorg = u['origin']
    backup_status = u['state']
    backup[srvuuidorg] = backup_status

I extract machine hostname, then check if this hostname exist in hosts dictionary and get the output with srvuuid

hostname = gethostname()
print(hostname)
for srvhostname in hosts:
  if srvhostname != hostname:
    continue
  if srvhostname == hostname:
    print(srvhostname + " : " + hosts[srvhostname])
    break
  else:
    print("There is no matching hostname or uuid.")

At the end I want to compare srvuuid and srvuuidorg. The code below is not working which means there is no output when executing:

for srvuuidorg in backup:
  if srvuuidorg != srvuuid:
      continue
  if srvuuidorg == srvuuid:
      print("Status for " + srvuuidorg + " is " + backup_status)
      break
  else:
      print("No maching uuid found.")

How should I compare two values from this dictionaries or maybe I should change approach to the subject and use something different than comparing dictionaries?

first use `print()` to see what you have in variables and see if values are the same. — furas, Oct 31 '19 at 08:53
if you use `for variable in dictionary` then you get keys, not values. You may need `for key,value in dictionary.items()` — furas, Oct 31 '19 at 08:54
Have a look at this for iterating over dicts https://stackoverflow.com/questions/3294889/iterating-over-dictionaries-using-for-loops — Pritish kumar, Oct 31 '19 at 09:18
Just a hint though: if you're iterating on a dict to find a given key or value then you're doing it wrong - the whole point of dicts is to have direct access to values thru keys. — bruno desthuilliers, Oct 31 '19 at 09:32

jon · Answer 1 · 2019-10-31T09:49:48.503

I think what you might want is:

srvuuid_match = False

for srvuuidorg in backup:
    if srvuuidorg == srvuuid:
        print("Status for " + srvuuidorg + " is " + backup[srvuuidorg])
        srvuuid_match = True
        break

if srvuuid_match is False:
    print("No maching uuid found.")

This will print the value stored on the srvuuidorg key of the backup dictionary. I think the problem you were having is that you were using the old value of backup_status from your previous chunk of code, rather than the right value of backup_status stored on the backup[srvuuidorg] dict and key.

However, it's not necessary to loop. You could do:

if srvuuid in backup:
    print("Status for " + srvuuidorg + " is " + backup[srvuuid])
else:
    print("No maching uuid found.")

If srvuuidorg == srvuuid (i.e. the srvuuid key exists in the backup dict), this will print the value stored on the srvuuid key in the backup dictionary. That might be a better way of doing it. Hope that helps!

gstukelj · Answer 2 · 2019-10-31T09:32:21.163

You don't need to loop over a dict to see if key is present, lookup time is O(1):

hostname = gethostname()
print(hostname)

if hostname in hosts:
    print(srvhostname + " : " + hosts[hostname])
    #srvuuid = hosts[hostname]                      ## I'm just guessing here 
else:
    print("There is no matching hostname or uuid.")

if srvuuid in backup:
    print("Status for " + backup[srvuuid] + " is " + backup_status)
else:
    print("No maching uuid found.")

Can't compare variables from two dictionaries in Python

2 Answers2