Trying to include a null value when not finding a given dictionary key

Question

I have a list of equipment software, and I'm trying to make a dictionary with the key being the name of the software and value an array of all versions to this key.

Equipment software list format

[
    [
        {"name": "openjdk-8-jre", "version": "8u171-b11-1~deb9u1"},
        {"name": "python2.7", "version": "2.7.13"},
        {"name": "npm", "version": "8.0.0"},
    ],
    [
        {"name": "openjdk-8-jre", "version": "8u171-b11-1~deb9u1"},
    ],
    [
        {"name": "python2.7", "version": "2.7.13"},
        {"name": "npm", "version": "7.0.0"},
    ],
]

What I'm trying:

softwares = {}

for software in all_equipment_softwares:
    softwares[software] = []

for equipment in equipments_dump:
    for software in equipment["softwares"]:
        software_name = software["name"]
        software_version = software["version"]

        softwares[software_name].append(software_version)

What I'm getting:

[
    {"openjdk-8-jre": ["8u171-b11-1~deb9u1", "8u171-b11-1~deb9u1"]},
    {"python2.7": ["2.7.13", "2.7.13"]},
    {"npm": ["8.0.0", "7.0.0"]},
]

I've been trying to break my head for hours, but I can't get the expected result

The expected result:

[
    {"openjdk-8-jre": ["8u171-b11-1~deb9u1", "8u171-b11-1~deb9u1", None]},
    {"python2.7": ["2.7.13", None, "2.7.13"]},
    {"npm": ["8.0.0", None, "7.0.0"]},
]

How can I add a null value in the values of a given key when the software is not present on that equipment?

What result are you actually getting, and why can't you fix it? — Scott Hunter
– Scott Hunter, Commented Sep 22, 2022 at 19:57
What happens when you run your code? Do you get an error? If so, what is it? Pleaseedit your question to include more detail. — Code-Apprentice
– Code-Apprentice, Commented Sep 22, 2022 at 20:26

holts-shoe · Accepted Answer · 2022-09-22 20:23:37Z

Here's an approach you could use to get an output with a single dictionary, instead of a list of dictionaries. The key insight is to prepopulate the value with a list of None. Feel free to ask for any clarifying questions.

softwares = {}
softwares_length = len(all_equipment_softwares)

#iterate through each software_list of all_equipment_softwares
for count, software_list in enumerate(all_equipment_softwares):

    #iterate through each software of software_list
    for software in software_list:

        #if it's a software we haven't seen add it to our dictionary with an array full of None based on the length of all_equipment_softwares
        if software['name'] not in softwares:
            softwares[software['name']] = [None] * softwares_length

        #update the dictionary value (the list) from None to the software version
        softwares[software['name']][count] = software['version']
print(software)

Output

{'openjdk-8-jre': ['8u171-b11-1~deb9u1', '8u171-b11-1~deb9u1', None],
'python2.7': ['2.7.13', None, '2.7.13'],
'npm': ['8.0.0', None, '7.0.0']}

J_H · Accepted Answer · 2022-09-22 19:57:16Z

0

    software_version = software["version"]

Your question was a bit vague. I assume the above blows up with KeyError when the software is not present on that equipment.

Use:

    software_version = software.get("version")

Also, please RTFM: https://docs.python.org/3/library/stdtypes.html#dict.get

answered Sep 22, 2022 at 19:57

J_H

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