The document provides solutions to three questions involving exception handling in Python. It includes examples for calculating the average of columns from a CSV file, finding the average of a list of integers, and summing the rows of a text file, while handling potential exceptions like file not found, empty files, and non-integer values. Custom exceptions are defined, and error handling is demonstrated in each solution.

1. EXCEPTION HANDLING
IN PYTHON
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2. Question 1.
Write a Python program that reads a CSV file containing integers and calculates
the average of each column in the file. Handle the exceptions that may arise if
the file does not exist, if the file is empty, or if any of the elements in the file is
not an integer.
Solution :
import csv
class EmptyFileError(Exception):
pass
class NonIntegerError(Exception):
pass
try:
with open("file.csv") as f:
reader = csv.reader(f)
data = list(reader)
if len(data) == 0:
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3. raise EmptyFileError
averages = []
for i in range(len(data[0])):
total = 0
count = 0
for j in range(len(data)):
try:
num = int(data[j][i])
total += num
count += 1
except ValueError:
pass
except IndexError:
pass
if count == 0:
raise NonIntegerError
averages.append(total / count)
print("Averages: ", averages)
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4. except FileNotFoundError:
print("Error: file not found")
except EmptyFileError:
print("Error: the file is empty")
except NonIntegerError:
print("Error: some columns contain only non-integer values")
Question 2:
Write a Python function that takes a list of integers as input and returns the
average of the integers. If the list is empty, raise a custom exception
"EmptyListError". If any of the elements in the list is not an integer, skip that
element and continue calculating the average.
Solution :
class EmptyListError(Exception):
pass
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5. class EmptyListError(Exception):
pass
def difference(lst):
try:
if len(lst) == 0:
raise EmptyListError
nums = []
for i in lst:
if isinstance(i, int):
nums.append(i)
if len(nums) == 0:
raise ValueError
return max(nums) - min(nums)
except EmptyListError:
print("Error: the list is empty")
except ValueError:
print("Error: all elements in the list are non-integer values").
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6. Question 3:
Write a Python program that reads a file containing integers and calculates the
sum of each row in the file. Handle the exceptions that may arise if the file does
not exist, if the file is empty, or if any of the elements in the file is not an integer.
Solution:
class EmptyFileError(Exception):
pass
class NonIntegerError(Exception):
pass
try:
with open("file.txt") as f:
data = f.readlines()
if len(data) == 0:
raise EmptyFileError
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7. sums = []
for row in data:
row_sum = 0
nums = row.split()
for num in nums:
try:
row_sum += int(num)
except ValueError:
pass
if len(nums) == 0:
raise NonIntegerError
sums.append(row_sum)
print("Sums: ", sums)
except FileNotFoundError:
print("Error: file not found")
except EmptyFileError:
print("Error: the file is empty")
except NonIntegerError:
print("Error: some rows contain only non-integer values").
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