如何从 python 中的列表列表中创建字典列表？

Question

There is the list of lists, named "people": people=[['Sara Smith', 42, 'female', 35000], ['John Lee', 25, 'male', 25000]] I'd like to create the list of dictionaries: person=[{'name:'Sara Smith', 'age':42, 'gender':'female', 'income':35000}, {'name:'John Lee', 'age':25, 'gender':'male', 'income':25000}] How can I do it?

I tried this:

fields=['name', 'age', 'gender', 'income']
print(len(people))
for i in range(0, len(people)):
    exec("people%d = %s" % (i + 1, repr(people[i])));
    person=[]
    person.append(dict(zip(fields, people[i])))
    print(people[i])
print(person)

But for some reason, as a result of "print(person)" I have [{'name': 'John Lee', 'age': 25, 'gender': 'male', 'income': 25000}]. I cannot understand, why my result includes only a dictionary for people[1] in the list and maybe there are some more elegant solutions for the task

Answer 1

You could use dict() and zip fields into each using a list comprehension.

people=[['Sara Smith', 42, 'female', 35000], ['John Lee', 25, 'male', 25000]]
fields = ['name', 'age', 'gender', 'income']

dict_people = [dict(zip(fields, l)) for l in people]

Result:

[{'name': 'Sara Smith', 'age': 42, 'gender': 'female', 'income': 35000}, {'name':'John Lee', 'age': 25, 'gender': 'male','income': 25000}]

Answer 2

This is a much cleaner way to do it

people=[['Sara Smith', 42, 'female', 35000], ['John Lee', 25, 'male', 25000]]
fields=['name', 'age', 'gender', 'income']
person=[]
for i in people:
    person.append(dict(zip(fields, i)))
print(person)

Output is:

[{'name': 'Sara Smith', 'age': 42, 'gender': 'female', 'income': 35000}, {'name': 'John Lee', 'age': 25, 'gender': 'male', 'income': 25000}]

Answer 3

You can actually do this all with a single dictionary comprehension. I'd really really recommend avoiding using exec unless you absolutely need to.

Try something like this instead:

person_dicts = [{"name": person[0], "age": person[1], "gender": person[2], "income": person[3]} for person in people]

Outputs:

[{'name': 'Sara Smith', 'age': 42, 'gender': 'female', 'income': 35000}, {'name': 'John Lee', 'age': 25, 'gender': 'male', 'income': 25000}]

Although this assumes your people list's sublist for a single person is always ordered the same way.

Edit:

If you don't want to use comprehensions you can always just use a for loop too.

person_dicts = []
for person in people:
    person_dicts.append({"name": person[0], "age": person[1], "gender": person[2], "income": person[3]})

Answer 4

You can do with zip as mentioned before:

people=[['Sara Smith', 42, 'female', 35000], ['John Lee', 25, 'male', 25000]]
fields=['name', 'age', 'gender', 'income']

persons = []
for person in people:
    tmp_dict = {}
    for key, value in zip(fields, person):
        tmp_dict[key] = value
    persons.append(tmp_dict)

Results:

[
  {'age': 42, 'gender': 'female', 'income': 35000, 'name': 'Sara Smith'},
  {'age': 25, 'gender': 'male', 'income': 25000, 'name': 'John Lee'},
]