Search text for a prefix and list all its suffixes in the text

Question

I use "suffix" loosely here to mean "any sub-string that follows the prefix".

"Prefix" here means the START of a word, where a word's start is defined as either after a space or from the first character of the input text (for the first word). A "prefix" in the middle of a word is ignored.

E.g. if your input prefix is "arm" and the input text is "Dumbledore's army was fully armed for the impending armageddon" then the output list contains (y, ed, ageddon).

Test Cases

Assume case-sensitive, strings end after spaces. Input will not start with a space.

Removing duplicates is optional.

---

Input prefix: "1"

Input text:

"He1in aosl 1ll j21j 1lj2j 1lj2 1ll l1j2i"

Output: (ll, lj2j, lj2) - in any permutation

---

Input prefix: "frac"

Input text: 

"fracking fractals fracted fractional currency fractionally fractioned into fractious fractostratic fractures causing quite a fracas"

Output: (king, tals, ted, tional, tionally, tioned, tious, tostratic, tures, as)

---

Input prefix: "href="https://www.astrotheme.com/astrology/"

Input text: 

"(div style="padding: 0; background: url('https://www.astrotheme.com/images/site/arrondi_450_hd.png') no-repeat; text-align: left; font-weight: bold; width: 450px; height: 36px")
  (div class="titreFiche" style="padding: 5px 0 0 6px")(a href="https://www.astrotheme.com/astrology/Nolwenn_Leroy" title="Nolwenn Leroy: Astrology, birth chart, horoscope and astrological portrait")Nolwenn Leroy(br /)
(/div)
  (div style="text-align: right; border-left: 1px solid #b2c1e2; border-right: 1px solid #b2c1e2; width: 446px; padding: 1px 1px 0; background: #eff8ff")
    (table style="width: 100%")(tr)(td style="width: 220px")
(div style="padding: 0; background: url('https://www.astrotheme.com/images/site/arrondi_450_hd.png') no-repeat; text-align: left; font-weight: bold; width: 450px; height: 36px")
  (div class="titreFiche" style="padding: 5px 0 0 6px")(a href="https://www.astrotheme.com/astrology/Kim_Kardashian" title="Kim Kardashian: Astrology, birth chart, horoscope and astrological portrait")Kim Kardashian(br /)(span style="font-weight: normal; font-size: 11px")Display her detailed horoscope and birth chart(/span)(/a)(/div)
(/div)
(div style="padding: 0; background: url('https://www.astrotheme.com/images/site/arrondi_450_hd.png') no-repeat; text-align: left; font-weight: bold; width: 450px; height: 36px")
  (div class="titreFiche" style="padding: 5px 0 0 6px")(a href="https://www.astrotheme.com/astrology/Julia_Roberts" title="Julia Roberts: Astrology, birth chart, horoscope and astrological portrait")Julia Roberts(br /)(span style="font-weight: normal; font-size: 11px")Display her detailed horoscope and birth chart(/span)(/a)(/div)
    (td id="cfcXkw9aycuj35h" style="text-align: right")
  (/div)"

Output: (Nolwenn_Leroy", Kim_Kardashian", Julia_Roberts")

The Winner

This is code-golf, so the fewest bytes wins. :)

Can accept the inputs in any way that works, as long as your code can solve arbitrary problems like the test cases.

Answer 1

R, 63 bytes

function(s,p,z=el(strsplit(s,' ')))sub(p,'',z[startsWith(z,p)])

Try it online!

The positive-lookbehind implementation is unfortunately 5 bytes longer due to the huge regmatches/gregexpr combination :

function(s,p)regmatches(s,gregexpr(paste0('(?<=',p,')[^ ]*'),s,,T))

Answer 2

Jelly, 12 bytes

Ḳfṛ"€¥Ḋ€ṫ€L}

Try it online!

Answer 3

C (gcc), 113 109 106 105 bytes

-4 bytes thanks to @LambdaBeta!
-3 bytes thanks to @WindmillCookies!

i;f(char*s,char*t){for(i=strlen(s);*t;t++)if(!strncmp(t,s,i))for(t+=i,puts("");*t^32&&*t;)putchar(*t++);}

Try it online!

Answer 4

Python 2, 57 56 bytes

lambda i,j:[w[len(i):]for w in j.split()if w.find(i)==0]

Try it online!

-1 with thanks to @mypetlion

Answer 5

Japt, 9 bytes

8 bytes if we can take input as an array of words.

¸kbV msVl
¸         // Shorthand for `qS`, split into words.
 kbV      // Filter the words, selecting only those that start with the prefix.
     msVl // For each remaining word, remove prefix length chars from the start.

Try it online!

Answer 6

Retina, 31 bytes

L`(?<=^\2¶(.|¶)*([^ ¶]+))[^ ¶]+

Try it online! First line should be the desired prefix, the rest is the input text. Does not remove duplicates. Would be 25 bytes if any white space was a valid seprator. Explanation: We want to list the suffixes of valid prefixes. The [^ ¶]+ matches the suffix itself. The prefix of the regexp is a lookbehind that ensures that the prefix of the suffix is the input prefix. As a lookbehind is evaluated right-to-left, this starts by matching the prefix (using the same pattern but inside ()s to capture it), then any characters, before finally matching the prefix on its own line at the beginning of the input.

Answer 7

Japt, 16 12 bytes

Port of Arnauld Answer

-4 bytes from @Shaggy

iS qS+V Å®¸g

iS                  Insert S value (S = " ") at beginning of first input (Implicit)
   q                split using
    S+V             S + Second input
        Å           slice 1
         ®          map
          ¸         split using S
           g        get first position

Try it online!

Answer 8

05AB1E, 11 bytes

#ʒηså}εsgF¦

Try it online! (here is a demo for multiline strings)

How does it work?

#ʒηså}εsgF¦    Full program.
#              Split the first input by spaces.
 ʒ   }         Filter the words by ...
  ηså          ... "Does the second input occur in the prefixed of the word?"
      ε        And for each valid word
       sg      Retrieve the length of the of the second input.
         F¦    And drop the first character of the word that number of times.

Answer 9

Stax, 8 bytes

·B¬╤²*6&

Run and debug it

Explanation:

j{x:[fmx|- Full program, implicit input: On stack in order, 1st input in X register
j          Split string on spaces
 {   f     Filter:
  x:[        Is X a prefix?
      m    Map passing elements:
       x|-   Remove all characters in X the first time they occur in the element
             Implicit output

I could also use x%t (length of X, trim from left), which is equally long but packs to 9 bytes.

Answer 10

Brachylog, 24 21 bytes

tṇ₁W&h;Wz{tR&h;.cR∧}ˢ

Try it online!

Could have been a few bytes shorter if there was variable sharing with inline predicates.

Input is an array with the prefix as the first element and the text as the second element.

tṇ₁W                    % Split the text at spaces, call that W
    &h;Wz               % Zip the prefix with each word, to give a list of pairs
         {         }ˢ   % Select the outputs where this predicate succeeds:
          tR            % Call the current word R
            &h;.c       % The prefix and the output concatenated
                 R      % should be R
                  ∧     % (No more constraints on output)

Answer 11

IBM/Lotus Notes Formula, 54 bytes

c:=@Explode(b);@Trim(@If(@Begins(c;a);@Right(c;a);""))

Takes it's input from two fields named a and b. Works because Formula will recursively apply a function to a list without the need for a @For loop.

No TIO available so here's a screenshot:

Answer 12

APL (Dyalog Unicode), 23 bytes^SBCS

Full program. Prompts for text and prefix from stdin. Prints list to stdout.

(5⌽'(\w+)\b',⎕)⎕S'\1'⊢⎕

Try it online!

⎕ prompt (for text)

⊢ yield that (separates '\1' from ⎕)

(…)⎕S'\1' PCRE Search and return list of capture group 1 from the following regex:

 ⎕ prompt (for prefix)

 '(\w+)\b', prepend this string (group of word characters followed by a word boundary)

 5⌽ rotate the first 5 characters to the end; '\bPREFIX(\w+)'

Answer 13

MATL, 17 bytes

Yb94ih'(.*)'h6&XX

Try it on MATL Online

How?

Yb - Split the input at spaces, place the results in a cell array

94 - ASCII code for ^ character

ih - Get the input (say "frac"), concatenate '^' and the input

'(.*)'h - Push the string '(.*)' into the stack, concatenate '^frac' and '(.*)'. So now we have '^frac(.*), a regex that matches "frac" at the beginning of the string and captures whatever comes after.

6&XX - Run regexp matching, with 6& specifying 'Tokens' mode i.e., the matched capture groups are returned instead of the entire match.

Implicitly output the results.

Answer 14

C (clang), 107 bytes

i;f(s,t,_)char*s,*t,*_;{i=strlen(s);_=strtok(t," ");while((strncmp(_,s,i)||puts(_+i))&&(_=strtok(0," ")));}

Try it online!

Description:

i;f(s,t,_)char*s,*t,*_;{   // F takes s and t and uses i (int) and s,t,u (char*)
    i=strlen(s);           // save strlen(s) in i
    _=strtok(t," ");       // set _ to the first word of t
    while(                 // while loop
        (strncmp(_,s,i)||  // short-circuited if (if _ doesn't match s to i places)
         puts(_+i))        // print _ starting at the i'th character
        &&                 // the previous expression always returns true
        (_=strtok(0," "))) // set _ to the next word of t
    ;                      // do nothing in the actual loop
}

Has to be clang because gcc segfaults without #include <string.h> due to strtok problems.

Answer 15

PowerShell 3.0, 60 62 59 bytes

param($p,$s)-split$s|%{if($_-cmatch"^$p(.*)"){$Matches[1]}}

Lost some bytes suppressing the cmatch output. Had a janky solution that gained some by purposely causing duplicates. But it also threw redlines if it didn't match on the first but that is not fine now that I think about it. +2 bytes to fix it though.

Answer 16

Bash + grep, 20 bytes

grep -Po "\b$1\K\S*"

Prefix is given as a command-line parameter, and input text is piped in via stdin.

Try it online!

Answer 17

JavaScript (Node.js), 64 59 bytes

-5 bytes from @Shaggy

a=>b=>b.match(eval(`/\\b${a}\\w*/g`)).map(x=>x.split(a)[1])

Try it online!

Answer 18

JavaScript (ES6), 57 bytes

Takes input in currying syntax (text)(prefix). Does not remove duplicates.

s=>p=>(' '+s).split(' '+p).slice(1).map(s=>s.split` `[0])

Try it online!

Answer 19

Perl 6, 30 bytes

{$^t.comb: /[^|' ']$^p <(\S+/}

Test it

Expanded:

{  # bare block lambda with placeholder params $p, $t

  $^t.comb:    # find all the substrings that match the following
  /
    [ ^ | ' ' ] # beginning of string or space
    $^p        # match the prefix
    <(         # don't include anything before this
    \S+        # one or more non-space characters (suffix)
  /
}

Answer 20

Perl 5 with -asE, 23 22 21 bytes (?)

say/^$b(.*)/ for@F

Try it online!

Can be run as a commandline one-liner as perl -asE 'say/^$b(.*)/ for@F' -- -b=frac -, or with a filename in place of the last -.
Or from a script file, say perl -as -M5.010 script.pl -b=frac - (thanks to @Brad Gilbert b2gills for the TIO link demonstrating this).

The code itself is 18 bytes, I added 3 bytes for the -b= option which assigns its value (the prefix input) to a variable named $b in the code. That felt like an exception to the usual "flags aren't counted" consensus.

-a splits each input line at spaces and places the result in the array @F. -s is a shortcut way of assigning a command-line argument as a variable, by giving a name on the command-line. Here the argument is -b=frac, which places the prefix "frac" in a variable $b.

/^$b(.*)/ - Matches the value of $b at the beginning of the string. .* is whatever comes after that, until the end of the word, and the surrounding parantheses capture this value. The captured values are automatically returned, to be printed by say. Iterating through space-separated words with for @F means we don't have to check for initial or final spaces.

Answer 21

Jelly,  11  9 bytes

Ḳœṣ€ḢÐḟj€

A dyadic link accepting the text (a list of characters) on the left and the prefix (a list of characters) on the right which yields a list of lists of characters (the resulting suffixes).

Try it online! (footer joins with spaces to avoid full-program's implicit smashing)
Note: I added three edge cases to the string in the OP - unfrackled and nofracfracheremate to the beginning, which should not output and fracfracit to the end which should output fracit.

How?

Ḳœṣ€ḢÐḟj€ - Link: text, prefix                        e.g. "fracfracit unfracked", "frac"
Ḳ         - split (text) at spaces -> list of words        ["fracfracit", "unfracked"]
   €      - for each (word):
 œṣ       -   split around sublists equal to (prefix)       ["","","it"]  ["un","ked"]
     Ðḟ   - filter discard items for which this is truthy:
    Ḣ     -   head
          -   -- Crucially this modifies the list:             ["","it"]       ["ked"]
          -   -- and yields the popped item:                 ""            "un"
          -   -- and only non-empty lists are truthy:       kept          discarded
          -            ...so we end up with the list:      [["","it"]]
        € - for each (remaining list of lists of characters):
       j  -   join with the prefix                          "fracit"                                             
          -                                                ["fracit"]

---

previous 11 byter:

Ḳs€L}Ḣ⁼¥ƇẎ€

Also a dyadic link as above.

Try it online!

Answer 22

Haskell, 51 bytes

p#x=[length p`drop`y|y<-words x,and$zipWith(==)p y]

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Answer 23

Husk, 11 bytes

Pretty much just a port of the Haskell answer:

m↓L⁰foΠz=⁰w

Try it online!

Explanation

m↓L⁰f(Πz=⁰)w  -- prefix is explicit argument ⁰, the other one implicit. eg: ⁰ = "ab" and implicit "abc def"
           w  -- words: ["abc","def"]
    f(    )   -- filter by (example w/ "abc"
       z=⁰    -- | zip ⁰ and element with equality: [1,1]
      Π       -- | product: 1
              -- : ["abc"]
m             -- map the following
 ↓            -- | drop n elements
  L⁰          -- | n being the length of ⁰ (2)
              -- : ["c"]

Answer 24

Java 10, 94 bytes

p->s->{for(var w:s.split(" "))if(w.startsWith(p))System.out.println(w.substring(p.length()));}

Try it online here.

Ungolfed:

p -> s -> { // lambda taking prefix and text as Strings in currying syntax
    for(var w:s.split(" ")) // split the String into words (delimited by a space); for each word ...
        if(w.startsWith(p)) //  ... test whether p is a prefix ...
            System.out.println(w.substring(p.length())); // ... if it is, output the suffix
}

Answer 25

Small Basic, 242 bytes

A Script that takes no input and outputs to the TextWindow Object

c=TextWindow.Read()
s=TextWindow.Read()
i=1
While i>0
i=Text.GetIndexOf(s," ")
w=Text.GetSubText(s,1,i)
If Text.StartsWith(w,c)Then
TextWindow.WriteLine(Text.GetSubTextToEnd(w,Text.GetLength(c)+1))
EndIf
s=Text.GetSubTextToEnd(s,i+1)
EndWhile

Try it at SmallBasic.com! Requires IE/Silverlight

Answer 26

Python 2, 53 bytes

lambda i,j:[w.split()[0]for w in j.split(i)if len(w)]

Try it online!

Answer 27

Brachylog, 12 bytes

hṇ₁∋R&t;.cR∧

Try it online!

Takes input as [text, prefix] through the input variable, and generates each word through the output variable. This was originally sundar's answer, which I started trying to golf after reading that it "could have been a few bytes shorter if there was variable sharing with inline predicates", which is possible now. Turns out that generator output saves even more bytes.

    R           R
   ∋            is an element of
h               the first element of
                the input
 ṇ₁             split on spaces,
     &          and the input
      t         's last element
         c      concatenated
       ;        with
        .       the output variable
          R     is R
           ∧    (which is not necessarily equal to the output).

My first two attempts at golfing it down, using fairly new features of the language:

With the global variables that had been hoped for: hA⁰&tṇ₁{∧A⁰;.c?∧}ˢ (18 bytes)

With the apply-to-head metapredicate: ṇ₁ᵗz{tR&h;.cR∧}ˢ (16 bytes)

And my original solution:

Brachylog, 15 bytes

ṇ₁ʰlᵗ↙X⟨∋a₀⟩b↙X

Try it online!

Same I/O. This is essentially a generator for words with the prefix, ṇ₁ʰ⟨∋a₀⟩, modified to remove the prefix.

                   The input variable
  ʰ                with its first element replaced with itself
ṇ₁                 split on spaces
    ᵗ              has a last element
   l               the length of which
     ↙X            is X,
       ⟨   ⟩       and the output from the sandwich
       ⟨∋  ⟩       is an element of the first element of the modified input
       ⟨ a₀⟩       and has the last element of the input as a prefix.
                   The output variable
       ⟨   ⟩       is the output from the sandwich
            b      with a number of characters removed from the beginning
             ↙X    equal to X.

A very different predicate with the same byte count:

Brachylog, 15 bytes

hṇ₁∋~c₂Xh~t?∧Xt

Try it online!

Same I/O.

   ∋               An element of
h                  the first element of
                   the input variable
 ṇ₁                split on spaces
    ~c             can be un-concatenated
      ₂            into a list of two strings
       X           which we'll call X.
        h          Its first element
         ~t        is the last element of
           ?       the input variable,
            ∧      and
             Xt    its last element is
                   the output variable.

Answer 28

Red, 62 bytes

func[p s][parse s[collect[any[p keep to[" "| end]| thru" "]]]]

Try it online!

Answer 29

Pyth, 21 20 18 17 16 bytes

AQVcH)IqxNG0:NG"

Try it online!

-1 by using V instead of FN because V implicitly sets N

-2 after some further reading about string slicing options

-1 using x to check for the presence of the substring at index 0

-1 using replace with "" for getting the end of the string

I'm sure this could use some serious golfing but as a Pyth beginner, just getting it to work was a bonus.

How does it work?

assign('Q',eval_input())
assign('[G,H]',Q)
for N in num_to_range(chop(H)):
    if equal(index(N,G),0):
        imp_print(at_slice(N,G,""))

Answer 30

Excel VBA, 86 bytes

Takes input as prefix in [A1] and values in [B1] and outputs to the console.

For each w in Split([B1]):?IIf(Left(w,[Len(A1)])=[A1],Mid(w,[Len(A1)+1])+" ","");:Next

Answer 31

C (gcc), 99 bytes

This uses strsep instead of strtok, saving a few bytes. Oddly, I had to include the function prototype for strsep (and strtok) to avoid segment faults when not including string.h.

char*strsep();w;f(s,t,u)char*s,*t,*u;{for(w=strlen(t);u=strsep(&s," ");)strncmp(u,t,w)||puts(u+w);}

Try it online!