Selectively replace multiple instances of a character within a string

Selectively replace multiple instances of a character within a string is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

Task

This is admittedly a trivial task but I thought it would be interesting to see how succinctly (or otherwise) different languages can handle it.

Given the string: "abracadabra", replace programatically:

• the first 'a' with 'A'
• the second 'a' with 'B'
• the fourth 'a' with 'C'
• the fifth 'a' with 'D'
• the first 'b' with 'E'
• the second 'r' with 'F'

Note that there is no replacement for the third 'a', second 'b' or first 'r'.

The answer should, of course, be : "AErBcadCbFD".

Other tasks related to string operations:

Metrics

• Array length
• String length
• Copy a string
• Empty string  (assignment)

Counting

• Word frequency
• Letter frequency
• Jewels and stones
• I before E except after C
• Bioinformatics/base count
• Count occurrences of a substring
• Count how many vowels and consonants occur in a string

Remove/replace

• XXXX redacted
• Conjugate a Latin verb
• Remove vowels from a string
• String interpolation (included)
• Strip block comments
• Strip comments from a string
• Strip a set of characters from a string
• Strip whitespace from a string -- top and tail
• Strip control codes and extended characters from a string

Anagrams/Derangements/shuffling

• Word wheel
• ABC problem
• Sattolo cycle
• Knuth shuffle
• Ordered words
• Superpermutation minimisation
• Textonyms (using a phone text pad)
• Anagrams
• Anagrams/Deranged anagrams
• Permutations/Derangements

Find/Search/Determine

• ABC words
• Odd words
• Word ladder
• Semordnilap
• Word search
• Wordiff  (game)
• String matching
• Tea cup rim text
• Alternade words
• Changeable words
• State name puzzle
• String comparison
• Unique characters
• Unique characters in each string
• Extract file extension
• Levenshtein distance
• Palindrome detection
• Common list elements
• Longest common suffix
• Longest common prefix
• Compare a list of strings
• Longest common substring
• Find common directory path
• Words from neighbour ones
• Change e letters to i in words
• Non-continuous subsequences
• Longest common subsequence
• Longest palindromic substrings
• Longest increasing subsequence
• Words containing "the" substring
• Sum of the digits of n is substring of n
• Determine if a string is numeric
• Determine if a string is collapsible
• Determine if a string is squeezable
• Determine if a string has all unique characters
• Determine if a string has all the same characters
• Longest substrings without repeating characters
• Find words which contains all the vowels
• Find words which contains most consonants
• Find words which contains more than 3 vowels
• Find words which first and last three letters are equals
• Find words which odd letters are consonants and even letters are vowels or vice_versa

Formatting

• Substring
• Rep-string
• Word wrap
• String case
• Align columns
• Literals/String
• Repeat a string
• Brace expansion
• Brace expansion using ranges
• Reverse a string
• Phrase reversals
• Comma quibbling
• Special characters
• String concatenation
• Substring/Top and tail
• Commatizing numbers
• Reverse words in a string
• Suffixation of decimal numbers
• Long literals, with continuations
• Numerical and alphabetical suffixes
• Abbreviations, easy
• Abbreviations, simple
• Abbreviations, automatic

Song lyrics/poems/Mad Libs/phrases

• Mad Libs
• Magic 8-ball
• 99 Bottles of Beer
• The Name Game (a song)
• The Old lady swallowed a fly
• The Twelve Days of Christmas

Tokenize

• Text between
• Tokenize a string
• Word break problem
• Tokenize a string with escaping
• Split a character string based on change of character

Sequences

• Show ASCII table
• De Bruijn sequences
• Self-referential sequences
• Generate lower case ASCII alphabet

Wren

Library: Wren-seq

Library: Wren-str

Library: Wren-regex

Not particularly succinct but, thanks to a recently added library method, better than it would have been :) <lang ecmascript>import "./seq" for Lst import "./str" for Str

var s = "abracadabra" var sl = s.toList var ixs = Lst.indicesOf(sl, "a")[2] var repl = "ABaCD" for (i in 0..4) sl[ixs[i]] = repl[i] s = sl.join() s = Str.replace(s, "b", "E", 1) s = Str.replace(s, "r", "F", 2, 1) System.print(s)</lang>

Output:

AErBcadCbFD

Alternatively, using regular expressions (embedded script) producing output as before. <lang ecmascript>import "./regex" for Regex

var s = "abracadabra" var re = Regex.compile("a") var split = re.split(s) var repl = "ABaCD" var res = "" for (i in 0...split.count-1) res = res + split[i] + repl[i] s = res + split[-1] s = Regex.compile("b").replace(s, "E") s = Regex.compile("r").replaceAll(s, "F", 2, 1) System.print(s)</lang>