根据每个元组的第一个值比较两个元组列表（但返回所有元组值）

Question

I am trying to compare the output of two different systems by finding devices that are unique in System A, unique in System B and finally devices that exist in both systems.

Right now I have my data coming out of both systems as a list of tuples. My example data looks like this:

system_a_devices = [("host1.test.local", "Test 1 Group"), ("host5.testing.lan", "LAN Test Group"), ("server5.hello.local", "Hello Corporation, Inc."), ("desktop1.corp.tld", "Corporate TLD, Ltd.")]

system_b_devices = [("desktop1.corp.tld", "Corporate TLD, Ltd."), ("host1.test.local", "Test One Group"), ("server6.hello.local", "Hello Corporation, Inc.")]

The first value in the tuple is the FQDN of the host and the second value is a descriptive name for the device (in this particular sample it's a customer name). While the customer name is needed in the final result, they do NOT necessarily need to match (see "Test One Group" and "Test 1 Group" yet they share the same FQDN). As such, the final result could contain the string "Test 1 Group" OR "Test One Group" as either will work for what I'm trying to accomplish (though System B most likely has the most accurate data for the customer name).

The FQDN (first value in the tuple) should be the only thing considered when determining the unique values from each system. Also, each of the two systems can return the list of systems in any random order and the number of tuples (FQDN/customer name pairings) per list from each system will vary.

My end result should look something similar to this:

system_a_unique = [("host5.testing.lan", "LAN Test Group"), ("server5.hello.local", "Hello Corporation, Inc.")]

system_b_unique = [("server6.hello.local", "Hello Corporation, Inc.")]

both_systems = [("host1.test.local", "Test One Group"), ("desktop1.corp.tld", "Corporate TLD, Ltd.")]

As I mentioned earlier, the description/customer name COULD come from either system for the "both_systems" list but System B probably has better/cleaner data if it's not too much work extra effort to use System B's data.

How would I efficiently accomplish this task? Would the better question to ask be how should I structure my data output from System A and System B to better accomplish this (ie list of tuples is a bad idea)?

Answer 1

Would the better question to ask be how should I structure my data output from System A and System B to better accomplish this (ie list of tuples is a bad idea)?

I have to say that, yes, a simple move to dict s would make this trivial.

system_a_devices = {"host1.test.local": "Test 1 Group", "host5.testing.lan": "LAN Test Group", "server5.hello.local": "Hello Corporation, Inc.", "desktop1.corp.tld": "Corporate TLD, Ltd."}
system_b_devices = {"desktop1.corp.tld": "Corporate TLD, Ltd.", "host1.test.local": "Test One Group", "server6.hello.local": "Hello Corporation, Inc."}

Now you can just do straightforward list comps:

system_a_unique = [tup for tup in system_a_devices.items() if tup[0] not in system_b_devices]
system_b_unique = [tup for tup in system_b_devices.items() if tup[0] not in system_a_devices]
both_systems = [tup for tup in system_b_devices.items() if tup[0] in system_a_devices]

Answer 2

You can use set operations on the FQDNs to find which are unique to each system and which are on both, and then use dicts to lookup the device names based on FQDNs:

# create FQDN -> device name dicts for each system
devices_a = dict(system_a_devices)
devices_b = dict(system_b_devices)

# create a set of FQDNs for each system
fqdn_set_a = set(system_a_devices.keys())
fqdn_set_b = set(system_b_devices.keys())

# compute FQDNs unique to each systems and those which are not unique
unique_fqdns_a = fqdn_set_a - fqdn_set_b
unique_fqdns_b = fqdn_set_b - fqdn_set_a
non_unique_fqdns = fqdn_set_a & fqdn_set_b

# now add device names using the FQDN -> device name dicts
system_a_unique = [(fqdn, devices_a[fqdn]) for fqdn in unique_fqdns_a]
system_b_unique = [(fqdn, devices_b[fqdn]) for fqdn in unique_fqdns_b]
# note: for FQDNs found on both systems, use the device name from system B
both_systems = [(fqdn, devices_b[fqdn]) for fqdn in non_unique_fqdns]