How to change a specific character from upper case to lower case using awk or sed or python?-CodePudding

I have a line with string of characters (BCCDDDCDCCDDDDDDABCDABCABDBACBDCAACCBBCABACBCCABCACBCDCCCBDBACDCBBCBCBCCCACADAACCABABADBCBAABBBCCBB)

I like to replace a specific character (for e.g, 4th character) to lower case.

I tried this awk command,

awk '{for (i=1; i<=NF; i) { $i=toupper(substr($i,1,1)) tolower(substr($i,2)); } print }' input > output

input file contains the string "BCCDDDCDCCDDDDDDABCDABCABDBACBDCAACCBBCABACBCCABCACBCDCCCBDBACDCBBCBCBCCCACADAACCABABADBCBAABBBCCBB"

This awk command gives this output: "Bccdddcdccddddddabcdabcabdbacbdcaaccbbcabacbccabcacbcdcccbdbacdcbbcbcbcccacadaaccababadbcbaabbbccbb"

Now, how do I change all the other characters to lowercase except the 4th character?

Thank you

CodePudding user response：

On that line you can use something like this. Through -F '' every letter is now a field which can be accessed with $i.

$ cat line
BCCDDDCDCCDDDDDDABCDABCABDBACBDCAACCBBCABACBCCABCACBCDCCCBDBACDCBBCBCBCCCACADAACCABABADBCBAABBBCCBB

$ awk -F '' '{ for(i=1;i<=NF;  i){
    if(i!=4){
      printf("%s",tolower($i))}
    else{
      printf("%s",$i)} } print "" }' line
bccDddcdccddddddabcdabcabdbacbdcaaccbbcabacbccabcacbcdcccbdbacdcbbcbcbcccacadaaccababadbcbaabbbccbb

CodePudding user response：

An example in python of a function that makes it, I let you understand the logic and adapt it to your problem.

def f(s):
    # your result
    res = ""

    # iterate though each character in the string
    for i in range(0, len(s)):

        # on some condition, here 4th character, you add a lowercase character to your result
        if(i == 3): 
            res  = s[i].lower()

        # on some other conditions an upper case character...
        elif condition_2_to_create: 
            res  = s[i].upper()

        # or just the character as it is in the string without modification
        else:
            res  = s[i]

    # Then return your result
    return res