The error message:
IndexError: cannot fit ‘int’ into an index-sized integer
occurs when you try to use an excessively large integer as an index in a sequence (like a list, tuple, or string). Python’s indexing system relies on a fixed-sized integer, and when a number exceeds the system’s limit, it raises this IndexError.
1. Causes and Solutions
Cause 1: Using an Extremely Large Index
Python sequences like lists, tuples, and strings have an index limit based on the system architecture. If the index exceeds this limit, Python raises an error.
Incorrect Code:
my_list = [1, 2, 3]
index = 10**100 # Extremely large number
print(my_list[index]) # Error: Index too large
Solution: Ensure the index is within a reasonable range.
if index < len(my_list):
print(my_list[index])
else:
print("Index is out of range")
Cause 2: Using an Integer Type That Exceeds the System Limit
In some cases, using an integer from a special data type (like NumPy’s int64) as an index may exceed Python’s limit.
Incorrect Code:
import numpy as np
arr = [10, 20, 30]
index = np.int64(2**63) # Too large for an index
print(arr[index]) # Error
Solution: Convert the index to a standard Python integer.
index = int(index) # Convert to a normal Python int
if index < len(arr):
print(arr[index])
Cause 3: Using a Large Floating-Point Number as an Index
Python does not allow float indices, but converting a large float to an integer may cause overflow.
Incorrect Code:
my_list = [5, 10, 15]
index = float(1e100) # Extremely large float
print(my_list[int(index)]) # Error
Solution: Convert to an integer only if it’s within a valid range.
index = int(index)
if 0 <= index < len(my_list):
print(my_list[index])
else:
print("Index is too large")
Cause 4: Incorrect Index Calculation Leading to Large Numbers
Some calculations may unintentionally create huge numbers that exceed indexing limits.
Incorrect Code:
my_list = [10, 20, 30]
index = sum([10**10] * 100) # Large number due to summation
print(my_list[index]) # Error
Solution: Ensure index calculations do not exceed reasonable bounds.
index = min(index, len(my_list) - 1) # Limit index to last valid position
print(my_list[index])