{"id":20565,"date":"2020-07-30T20:03:42","date_gmt":"2020-07-31T03:03:42","guid":{"rendered":"https:\/\/careerkarma.com\/blog\/?p=20565"},"modified":"2023-12-01T03:57:10","modified_gmt":"2023-12-01T11:57:10","slug":"python-typeerror-list-indices-must-be-integers-or-slices-not-str","status":"publish","type":"post","link":"https:\/\/careerkarma.com\/blog\/python-typeerror-list-indices-must-be-integers-or-slices-not-str\/","title":{"rendered":"Python typeerror: list indices must be integers or slices, not str Solution"},"content":{"rendered":"\n

String indices must be integers or slices, not strings? What does this error mean? It\u2019s a TypeError, which tells us that we are trying to perform an operation on a value whose type is not compatible with the operation. What\u2019s the solution?
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In this guide, we\u2019re going to answer all of those questions. We\u2019ll discuss what causes this error in Python and why it is raised. We\u2019ll walk through an example scenario to help you figure out how to solve it. Without further ado, let\u2019s begin!<\/p>\n\n\n\n

The Problem: typeerror: list indices must be integers or slices, not str<\/h2>\n\n\n\n

Houston, we have a TypeError:<\/p>\n\n\n\n

typeerror: list indices must be integers or slices, not str<\/pre><\/div>\n\n\n\n
This error is raised when you try to access a value inside a list<\/a> using a string value.
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Items in lists are indexed<\/a> using numbers. Consider the following list:
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0<\/td>1<\/td>2<\/td>3<\/td>4<\/td>5<\/td><\/tr>
S<\/td>t<\/td>r<\/td>i<\/td>n<\/td>g<\/td><\/tr><\/tbody><\/table>\n\n\n\n
<\/p>\n\n\n\n
To access values in this string, we can use index slicing. This is when you call a string followed by an index value to retrieve the character at that position:<\/p>\n\n\n\n
example_string = "String"\n\nprint(example_string[0])<\/pre><\/div>\n\n\n\n
This code returns: S<\/code>. Our code retrieves the character at the index position 0 in our list.
<\/p>\n\n\n\n
If you try to access a list using a letter, like “S”, an error will occur.<\/p>\n\n\n\n
An Example Scenario<\/h2>\n\n\n\n
The error “typeerror: list indices must be integers or slices, not str” is commonly raised when you try to access an item in a list of JSON objects<\/a> as if it were a list.
<\/p>\n\n\n\n
Consider the following code snippet:<\/p>\n\n\n\n
students = [\n\t{\n\t\t"name": "Lisa Simpson",\t\n\t\t"age": 8\n\t},\n\t{\n\t\t"name": "Janey Powell",\n\t\t"age": 9\n\t},\n\t{\n\t\t"name": "Ralph Wiggum",\n\t\t"age": 8\n\t}\n]\n\nto_find = input("Enter the name of the student whose age you want to find: ")\n\nfor s in students:\n\tif students["name"] == to_find:\n\t\tprint("The age of {} is {}.".format(students["name"], students["age"]))<\/pre><\/div>\n\n\n\n
This code snippet finds the age of a particular student in a class. First, we have declared a list of students. This list stores each student as a JSON object.
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Next, we ask the user to enter the name of the student whose age they want to find. Our program then iterates over each student in the list using a for loop<\/a> to find the student whose name matches the one we have specified.
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If that particular name is found, the age of the student is printed to the console. Otherwise, nothing happens.
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Let\u2019s try to run our code:<\/p>\n\n\n\n
Traceback (most recent call last):\n  File "main.py", line 19, in <module>\n\tif students["name"] == to_find:\nTypeError: list indices must be integers or slices, not str<\/pre><\/div>\n\n\n\n
Oh no. It\u2019s a TypeError!<\/p>\n\n\n\n
The Solution<\/h2>\n\n\n\n
You can solve the error “typeerror: list indices must be integers or slices, not str” by making sure that you access items in a list using index numbers, not strings.
<\/p>\n\n\n\n
The problem in our code is that we’re trying to access “name” in our list of students:<\/p>\n\n\n\n
students["name"]<\/pre><\/div>\n\n\n\n
This corresponds with no value because our list contains multiple JSON objects. To solve this problem, we\u2019re going to use a range() statement<\/a> to iterate over our list of students. Then, we\u2019ll access each student by their index number:<\/p>\n\n\n\n
for s in range(len(students)):\n\tif students[s]["name"] == to_find:\n\t\tprint("The age of {} is {}.".format(students[s]["name"], students[s]["age"]))<\/pre><\/div>\n\n\n\n
To start, we have used a range statement. This will allow us to iterate over every student in our list. We\u2019ve replaced every instance of “students[“key_name”]” with “students[s][“key_name”]”. This allows us to access each value in the list.
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Let\u2019s run our code and see what happens:<\/p>\n\n\n\n
Enter the name of the student whose age you want to find: Lisa Simpson\nThe age of Lisa Simpson is 9.<\/pre><\/div>\n\n\n\n
Our code has successfully found the age of Lisa Simpson.
<\/p>\n\n\n\n
We access each value in the “students” list using its index number instead of a string. Problem solved!<\/p>\n\n\n\n