(Solved) Python TypeError: ‘float’ object is not subscriptable

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Problem Formulation

Consider the following minimal example where a TypeError: 'float' object is not subscriptable occurs:

variable = 42.42
x = variable[0]

This yields the following output:

Traceback (most recent call last):
  File "C:\Users\xcent\Desktop\code.py", line 2, in <module>
    x = variable[0]
TypeError: 'float' object is not subscriptable

Solution Overview

Python raises the TypeError: 'float' object is not subscriptable if you use indexing or slicing with the square bracket notation on a float variable that is not indexable.

However, the float class doesn’t define the __getitem__() method. 

variable = 1.23
variable[0]     # TypeError!
variable[1:10]  # TypeError!
variable[-1]    # TypeError!

You can fix this error by

  1. converting the float to a string using the str() function because strings are subscriptable,
  2. removing the indexing or slicing call,
  3. defining a dummy __getitem__() method for a custom float wrapper class.

🌍 Related Tutorials: Check out our tutorials on indexing and slicing on the Finxter blog to improve your skills!

Method 1: Convert Float to a String

If you want to access individual digits of the float value, consider converting the float to a string using the str() built-in function. A string is subscriptable so the error will not occur when trying to index or slice the converted string.

variable = 42.42
my_string = str(variable)

print(my_string[0])
# 4

print(my_string[1:4])
# 2.4

print(my_string[:-1])
# 42.4

Method 2: Put Float Into List

A simple way to resolve this error is to put the float into a list that is subscriptable—that is you can use indexing or slicing on lists that define the __getitem__() magic method. 

variable = [42.42]
x = variable[0]
print(x)
# 42.42

Or another example with multiple float values—now it starts to actually make sense:

sensor = [1.2, 2.1, 3.2, 0.9, 4.2]

print(sensor[0])
# 1.2

print(sensor[-1])
# 4.2

print(sensor[:])
# [1.2, 2.1, 3.2, 0.9, 4.2]

Method 3: Define the __getitem__() Magic Method

You can also define your own wrapper type around the float variable that defines a (dummy) method for __getitem__() so that every indexing or slicing operation returns the same float. 

class MyFloat:
    def __init__(self, f):
        self.f = f

    def __getitem__(self, index):
        return self.f


my_float = MyFloat(42.42)

print(my_float[0])
# 42.42

print(my_float[100])
# 42.42

This hack is generally not recommended, I included it just for comprehensibility and to teach you something new. 😉

Summary

The error message “TypeError: 'float' object is not subscriptable” happens if you access a float f like a list such as f[0]. To solve this error, avoid using slicing or indexing on a float but use a subscriptable object such as lists or strings.

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