如何从列表“ Python”中打印字典：

Question

lloyd = {
    "name": "Lloyd",
    "homework": [90.0, 97.0, 75.0, 92.0],
    "quizzes": [88.0, 40.0, 94.0],
    "tests": [75.0, 90.0]
}

students = ["lloyd","alice","tyler"]


#Accessing Dictionary from List

print students[0]['name']

Expected out is : Lloyd

whenever I run the above code I get this error,

===============================================
Traceback (most recent call last):
  File "python", line 30, in <module>
TypeError: string indices must be integers 
===============================================

Any help will be highly appreciated.

Answer 1

it's because students contains just strings ["lloyd","alice","tyler"]

print students[0]
>> "lloyd"

maybe you wanted to do this:

students = [lloyd]

then

print students[0]['name']

should work

Answer 2

You may want to place the dictionaries in the list rather than just the string names.

lloyd = {
    "name": "Lloyd",
    "homework": [90.0, 97.0, 75.0, 92.0],
    "quizzes": [88.0, 40.0, 94.0],
    "tests": [75.0, 90.0]
}

alice = {"name": "Alice "}
tyler = {"name": "Tyler "}

students = [lloyd, alice, tyler]

print students[0]['name']

Answer 3

Run the following command:

print students[0]

It will give your desired output.

Answer 4

Currently, students is just a list of strings. So the value of students[0] is a string, 'lloyd' , which is distinct from the dictionary you created with the name lloyd .

I think you want students to be a list of dictionaries. Below I've shown how to do that, and created empty dictionaries for alice and tyler . Then simply take the quotes away from your declaration of students to store the dictionaries instead of strings with the same names, and your last line works.

lloyd = {
    "name": "Lloyd",
    "homework": [90.0, 97.0, 75.0, 92.0],
    "quizzes": [88.0, 40.0, 94.0],
    "tests": [75.0, 90.0]
}

alice = {"name": "Alice"}

tyler = {"name": "Tyler"}

students = [lloyd,alice,tyler]

print students[0]['name']

which gives:

Lloyd

Answer 5

You are not using the dictionary lloyd defined at the top. When you create your list with students = ["lloyd","alice","tyler"], you are instead using the string "lloyd". So students[0] returns this string instead of the dict.

You need to use students = [lloyd,alice,tyler]. You might also want to create a dict for alice and tyler.

Answer 6

What you have tried is almost correct. You got an error because "string indices must be integers". So you can use eval() method in python ( python-eval-method ).

try the following code

lloyd = {
"name": "Lloyd",
"homework": [90.0, 97.0, 75.0, 92.0],
"quizzes": [88.0, 40.0, 94.0],
"tests": [75.0, 90.0]
}
students = ["lloyd","alice","tyler"]
#Accessing Dictionary from List
print eval(students[0])['name']

It will work

Answer 7

your students list contains just str objects.

print students[0]
>> "lloyd"

as you can see we got str object type.

you should fix it with this usage and removal of the the quotes:

students = [lloyd]
print students[0]['name']

Done ! :)

Even better to use the get method for dict usage:

print students[0].get('name')