Python Program to Converts Characters To Uppercase Around Numbers

Given a String, the following program converts the alphabetic character around any digit to its uppercase.

Input : test_str = ‘geeks4geeks is best1 f6or ge8eks’ 
Output : geekS4Geeks is besT1 F6Or gE8Ek 
Explanation : S and G are uppercased as surrounded by 4.
Input : test_str = ‘geeks4geeks best1 f6or ge8eks’ 
Output : geekS4Geeks besT1 F6Or gE8Ek 
Explanation : S and G are uppercased as surrounded by 4. 

Method 1 : Using upper(), loop and isdigit()

In this, we iterate for each character, check whether it’s a digit and if it is then, transform the surrounding alphabets(next and previous) to uppercase using upper().

Python3

# initializing string
test_str = 'geeks4geeks is best1 for ge8eks'

# printing original string
print("The original string is : " + str(test_str))

res = ''
for idx in range(len(test_str) - 1):
    if test_str[idx + 1].isdigit() or test_str[idx - 1].isdigit():
        res += test_str[idx].upper()
    else:
        res += test_str[idx]
#Adding last index character
else:
    res += test_str[idx+1]

# printing result
print("Transformed String : " + str(res))

Output

The original string is : geeks4geeks is best1 for ge8eks
Transformed String : geekS4Geeks is besT1 for gE8Eks

Time Complexity: O(n)
Auxiliary Space: O(n)

Method 2: Using list comprehension

This is similar to the above method, the only difference being that the following tackles the same problem in a single line.

Python3

# initializing string
test_str = 'geeks4geeks is best1 for ge8eks'

# printing original string
print("The original string is : " + str(test_str))

# list comprehension offering 1 liner solution
res = [test_str[idx].upper() if test_str[idx + 1].isdigit() or test_str[idx - 1].isdigit() else test_str[idx] for idx in range(len(test_str) - 1)]
res = res + list(test_str[-1])

# printing result
print("Transformed String : " + ''.join(res))

Output

The original string is : geeks4geeks is best1 for ge8eks
Transformed String : geekS4Geeks is besT1 for gE8Eks

Time Complexity: O(n)
Auxiliary Space: O(n)

Method #3 : By using array

Python3

# Python Program to Converts Characters To
# Uppercase Around Numbers initializing
# string
test_str = 'geeks4geeks is best1 for ge8eks'

# printing original string
print("The original string is : " + str(test_str))

res = ''
digits = "0123456789"
for idx in range(len(test_str) - 1):
    if test_str[idx + 1] in digits or test_str[idx - 1] in digits:
        res += test_str[idx].upper()
    else:
        res += test_str[idx]
# Adding last index character
else:
    res += test_str[idx+1]

# printing result
print("Transformed String : " + str(res))

Output

The original string is : geeks4geeks is best1 for ge8eks
Transformed String : geekS4Geeks is besT1 for gE8Eks

Method #4 : Using operator.countOf() method

Python3

# Python Program to Converts Characters To
# Uppercase Around Numbers initializing
# string
import operator as op

test_str = 'geeks4geeks is best1 for ge8eks'

# printing original string
print("The original string is : " + str(test_str))

res = ''
digits = "0123456789"
for idx in range(len(test_str) - 1):
    if op.countOf(digits, test_str[idx + 1]) > 0 or op.countOf(digits, test_str[idx - 1]) > 0:
        res += test_str[idx].upper()
    else:
        res += test_str[idx]
# Adding last index character
else:
    res += test_str[idx+1]

# printing result
print("Transformed String : " + str(res))

Output

The original string is : geeks4geeks is best1 for ge8eks
Transformed String : geekS4Geeks is besT1 for gE8Eks

Time Complexity: O(n)
Auxiliary Space: O(n)

Method#5 :  Using a for loop and string slicing

Python3

test_str = 'geeks4geeks is best1 for ge8eks'
result = ''

# printing original string
print("The original string is : " + str(test_str))
for i in range(len(test_str)):
    if test_str[i-1:i+2].isdigit():
        result += test_str[i].upper()
    else:
        result += test_str[i]
print(result)
#This code is contributed by Vinay pinjala.

Output

The original string is : geeks4geeks is best1 for ge8eks
geeks4geeks is best1 for ge8eks

Time Complexity: O(n)
Auxiliary Space: O(n)