Dtjytyk

What would happen to a modern skyscraper if it rains micro blackholes?

Is it possible to make sharp wind that can cut stuff from afar?

Circuitry of TV splitters

What is the meaning of "of trouble" in the following sentence?

Accidentally leaked the solution to an assignment, what to do now? (I'm the prof)

Could a US political party gain complete control over the government by removing checks & balances?

Chess with symmetric move-square

Are white and non-white police officers equally likely to kill black suspects?

I see my dog run

Why is an old chain unsafe?

What do you call a Matrix-like slowdown and camera movement effect?

A function which translates a sentence to title-case

Why CLRS example on residual networks does not follows its formula?

Why was the small council so happy for Tyrion to become the Master of Coin?

Why is "Reports" in sentence down without "The"

Can town administrative "code" overule state laws like those forbidding trespassing?

How did the USSR manage to innovate in an environment characterized by government censorship and high bureaucracy?

Why has Russell's definition of numbers using equivalence classes been finally abandoned? ( If it has actually been abandoned).

What is the offset in a seaplane's hull?

What typically incentivizes a professor to change jobs to a lower ranking university?

Download, install and reboot computer at night if needed

What is the command to reset a PC without deleting any files

DOS, create pipe for stdin/stdout of command.com(or 4dos.com) in C or Batch?

Are tax years 2016 & 2017 back taxes deductible for tax year 2018?

Extracting numeric values from a string containing key:value pairs

Simplify splitting a String into alpha and numeric partsRegex to remove inline javascript from stringExtraction of numbers from currency stringRemoving nested blocks from a stringExtracting tuples from Excel sheetRegex to obtain float values from a large text fileExtracting JSON from string using regexExtracting an IP address from a hosts file by hostnameExtracting parts of filenames from an arrayExtracting parameters from request URL path components using regexes

.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}

5

$begingroup$

I am writing function numericValues(text: String): List[Int] to extract patterns """([a-z]+)s*:s*(d+)""" and return the list of the numeric values :

numericValues("a123 : 0 abc:123 123:abc xyz:1") // List(123, 1)

I would write numericValues like this:

def numericValues(text: String): List[Int] = {

  val regex = """([a-z]+)s*:s*(d+)""".r

  regex.findAllIn(text).toList.flatMap {s =>

    PartialFunction.condOpt(s) { case regex(_, num) => num.toInt }

  }

}

I guess the condOpt invocation is redundant and I wonder how to simplify this implementation. Also, I'd appreciate comments on improvements to style and best practice.

regex scala

share|improve this question

edited Mar 20 at 21:30

Michael

asked Mar 20 at 10:20

MichaelMichael

1285

$endgroup$

add a comment | 

5

$begingroup$

I am writing function numericValues(text: String): List[Int] to extract patterns """([a-z]+)s*:s*(d+)""" and return the list of the numeric values :

numericValues("a123 : 0 abc:123 123:abc xyz:1") // List(123, 1)

I would write numericValues like this:

def numericValues(text: String): List[Int] = {

  val regex = """([a-z]+)s*:s*(d+)""".r

  regex.findAllIn(text).toList.flatMap {s =>

    PartialFunction.condOpt(s) { case regex(_, num) => num.toInt }

  }

}

I guess the condOpt invocation is redundant and I wonder how to simplify this implementation. Also, I'd appreciate comments on improvements to style and best practice.

regex scala

share|improve this question

edited Mar 20 at 21:30

Michael

asked Mar 20 at 10:20

MichaelMichael

1285

$endgroup$

add a comment | 

$begingroup$

I am writing function numericValues(text: String): List[Int] to extract patterns """([a-z]+)s*:s*(d+)""" and return the list of the numeric values :

numericValues("a123 : 0 abc:123 123:abc xyz:1") // List(123, 1)

I would write numericValues like this:

def numericValues(text: String): List[Int] = {

  val regex = """([a-z]+)s*:s*(d+)""".r

  regex.findAllIn(text).toList.flatMap {s =>

    PartialFunction.condOpt(s) { case regex(_, num) => num.toInt }

  }

}

I guess the condOpt invocation is redundant and I wonder how to simplify this implementation. Also, I'd appreciate comments on improvements to style and best practice.

regex scala

share|improve this question

edited Mar 20 at 21:30

Michael

asked Mar 20 at 10:20

MichaelMichael

1285

$endgroup$

numericValues("a123 : 0 abc:123 123:abc xyz:1") // List(123, 1)

def numericValues(text: String): List[Int] = {

  val regex = """([a-z]+)s*:s*(d+)""".r

  regex.findAllIn(text).toList.flatMap {s =>

    PartialFunction.condOpt(s) { case regex(_, num) => num.toInt }

  }

}

share|improve this question

edited Mar 20 at 21:30

Michael

asked Mar 20 at 10:20

MichaelMichael

1285

share|improve this question

edited Mar 20 at 21:30

Michael

asked Mar 20 at 10:20

MichaelMichael

1285

asked Mar 20 at 10:20

MichaelMichael

1285

asked Mar 20 at 10:20

MichaelMichael

1285

1 Answer
1

active

oldest

votes

7

$begingroup$

You usually want a zero-width word boundary b on either end of the regex, to avoid matching things like 1a:1a.

There's no need to capture [a-z]+ since you are throwing it away.

You can use lookbehind (?<=…) assertions to require a match to be preceded by whatever, without including the whatever in the match result. This means no need for capturing parenthesis, only the integer is included in the match, and the final map is simply _.toInt. Variable-width lookbehind was introduced in Java 9; older versions have only fixed-width lookbehind.

Finally, removing the variable makes braces unnecessary.

def numericValues(text: String): List[Int] = """(?<=b[a-z]+s*:s*)d+b""".r.findAllIn(text).toList.map(_.toInt)

With only fixed-width lookbehind, you could postprocess the matches to remove non-numerics:

….map(_.replaceAll("[^0-9]", "").toInt)

Or, more idiomatically and less hacky, just capture the digits and extract the capture groups:

"""b[a-z]+s*:s*(d+)b""".r.findAllIn(text).matchData.toList.map(_.group(1).toInt)

share|improve this answer

edited Mar 20 at 13:54

answered Mar 20 at 12:35

Oh My GoodnessOh My Goodness

2,202315

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Thanks a lot. What if I have only fixed-width lookbehind ?
  $endgroup$
  – Michael
  Mar 20 at 13:00
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  then you can't use variable-width lookbehind :) See edit.
  $endgroup$
  – Oh My Goodness
  Mar 20 at 13:56
  

  
  
  
  

add a comment | 

Your Answer

StackExchange.ifUsing("editor", function () {
return StackExchange.using("mathjaxEditing", function () {
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["\$", "\$"]]);
});
});
}, "mathjax-editing");

StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");

StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "196"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);

StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});

function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});


}
});

draft saved

draft discarded

Sign up or log in

StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});

Sign up using Google

Sign up using Facebook

Sign up using Email and Password

Post as a guest

Name

Email

Required, but never shown

StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fcodereview.stackexchange.com%2fquestions%2f215831%2fextracting-numeric-values-from-a-string-containing-keyvalue-pairs%23new-answer', 'question_page');
}
);

Post as a guest

Name

Email

Required, but never shown

7

$begingroup$

You usually want a zero-width word boundary b on either end of the regex, to avoid matching things like 1a:1a.

There's no need to capture [a-z]+ since you are throwing it away.

You can use lookbehind (?<=…) assertions to require a match to be preceded by whatever, without including the whatever in the match result. This means no need for capturing parenthesis, only the integer is included in the match, and the final map is simply _.toInt. Variable-width lookbehind was introduced in Java 9; older versions have only fixed-width lookbehind.

Finally, removing the variable makes braces unnecessary.

def numericValues(text: String): List[Int] = """(?<=b[a-z]+s*:s*)d+b""".r.findAllIn(text).toList.map(_.toInt)

With only fixed-width lookbehind, you could postprocess the matches to remove non-numerics:

….map(_.replaceAll("[^0-9]", "").toInt)

Or, more idiomatically and less hacky, just capture the digits and extract the capture groups:

"""b[a-z]+s*:s*(d+)b""".r.findAllIn(text).matchData.toList.map(_.group(1).toInt)

share|improve this answer

edited Mar 20 at 13:54

answered Mar 20 at 12:35

Oh My GoodnessOh My Goodness

2,202315

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Thanks a lot. What if I have only fixed-width lookbehind ?
  $endgroup$
  – Michael
  Mar 20 at 13:00
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  then you can't use variable-width lookbehind :) See edit.
  $endgroup$
  – Oh My Goodness
  Mar 20 at 13:56
  

  
  
  
  

add a comment | 

7

$begingroup$

You usually want a zero-width word boundary b on either end of the regex, to avoid matching things like 1a:1a.

There's no need to capture [a-z]+ since you are throwing it away.

You can use lookbehind (?<=…) assertions to require a match to be preceded by whatever, without including the whatever in the match result. This means no need for capturing parenthesis, only the integer is included in the match, and the final map is simply _.toInt. Variable-width lookbehind was introduced in Java 9; older versions have only fixed-width lookbehind.

Finally, removing the variable makes braces unnecessary.

def numericValues(text: String): List[Int] = """(?<=b[a-z]+s*:s*)d+b""".r.findAllIn(text).toList.map(_.toInt)

With only fixed-width lookbehind, you could postprocess the matches to remove non-numerics:

….map(_.replaceAll("[^0-9]", "").toInt)

Or, more idiomatically and less hacky, just capture the digits and extract the capture groups:

"""b[a-z]+s*:s*(d+)b""".r.findAllIn(text).matchData.toList.map(_.group(1).toInt)

share|improve this answer

edited Mar 20 at 13:54

answered Mar 20 at 12:35

Oh My GoodnessOh My Goodness

2,202315

$endgroup$

• 
  
  
  

  
  

  
  
  
  
  
  

  
  $begingroup$
  Thanks a lot. What if I have only fixed-width lookbehind ?
  $endgroup$
  – Michael
  Mar 20 at 13:00
  

  
  
  
  


• 
  
  
  

  
  1
  

  
  
  
  
  
  

  
  $begingroup$
  then you can't use variable-width lookbehind :) See edit.
  $endgroup$
  – Oh My Goodness
  Mar 20 at 13:56
  

  
  
  
  

add a comment | 

$begingroup$

You usually want a zero-width word boundary b on either end of the regex, to avoid matching things like 1a:1a.

There's no need to capture [a-z]+ since you are throwing it away.

You can use lookbehind (?<=…) assertions to require a match to be preceded by whatever, without including the whatever in the match result. This means no need for capturing parenthesis, only the integer is included in the match, and the final map is simply _.toInt. Variable-width lookbehind was introduced in Java 9; older versions have only fixed-width lookbehind.

Finally, removing the variable makes braces unnecessary.

def numericValues(text: String): List[Int] = """(?<=b[a-z]+s*:s*)d+b""".r.findAllIn(text).toList.map(_.toInt)

With only fixed-width lookbehind, you could postprocess the matches to remove non-numerics:

….map(_.replaceAll("[^0-9]", "").toInt)

Or, more idiomatically and less hacky, just capture the digits and extract the capture groups:

"""b[a-z]+s*:s*(d+)b""".r.findAllIn(text).matchData.toList.map(_.group(1).toInt)

share|improve this answer

edited Mar 20 at 13:54

answered Mar 20 at 12:35

Oh My GoodnessOh My Goodness

2,202315

$endgroup$

def numericValues(text: String): List[Int] = """(?<=b[a-z]+s*:s*)d+b""".r.findAllIn(text).toList.map(_.toInt)

….map(_.replaceAll("[^0-9]", "").toInt)

"""b[a-z]+s*:s*(d+)b""".r.findAllIn(text).matchData.toList.map(_.group(1).toInt)

share|improve this answer

edited Mar 20 at 13:54

answered Mar 20 at 12:35

Oh My GoodnessOh My Goodness

2,202315

answered Mar 20 at 12:35

Oh My GoodnessOh My Goodness

2,202315

answered Mar 20 at 12:35

Oh My GoodnessOh My Goodness

2,202315