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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
$begingroup$
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
asked 11 hours ago
MichaelMichael
1235
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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
asked 11 hours ago
MichaelMichael
1235
New contributor
Michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
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
asked 11 hours ago
MichaelMichael
1235
New contributor
Michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
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
regex scala
asked 11 hours ago
MichaelMichael
1235
New contributor
Michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 11 hours ago
MichaelMichael
1235
New contributor
Michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 5 mins ago
Michael
asked 11 hours ago
MichaelMichael
1235
New contributor
Michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 11 hours ago
MichaelMichael
1235
asked 11 hours ago
MichaelMichael
1235
1235
New contributor
Michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Michael is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
1 Answer
1
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oldest
votes
$begingroup$
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)
answered 9 hours ago
Oh My GoodnessOh My Goodness
1,554314
$endgroup$
$begingroup$
Thanks a lot. What if I have only fixed-width lookbehind ?
$endgroup$
– Michael
8 hours ago
1
$begingroup$
then you can't use variable-width lookbehind :) See edit.
$endgroup$
– Oh My Goodness
7 hours ago
add a comment |
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1 Answer
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1 Answer
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$begingroup$
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)
answered 9 hours ago
Oh My GoodnessOh My Goodness
1,554314
$endgroup$
$begingroup$
Thanks a lot. What if I have only fixed-width lookbehind ?
$endgroup$
– Michael
8 hours ago
1
$begingroup$
then you can't use variable-width lookbehind :) See edit.
$endgroup$
– Oh My Goodness
7 hours ago
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)
answered 9 hours ago
Oh My GoodnessOh My Goodness
1,554314
$endgroup$
$begingroup$
Thanks a lot. What if I have only fixed-width lookbehind ?
$endgroup$
– Michael
8 hours ago
1
$begingroup$
then you can't use variable-width lookbehind :) See edit.
$endgroup$
– Oh My Goodness
7 hours ago
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)
answered 9 hours ago
Oh My GoodnessOh My Goodness
1,554314
$endgroup$
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)
answered 9 hours ago
Oh My GoodnessOh My Goodness
1,554314
edited 7 hours ago
answered 9 hours ago
Oh My GoodnessOh My Goodness
1,554314
answered 9 hours ago
Oh My GoodnessOh My Goodness
1,554314
answered 9 hours ago
Oh My GoodnessOh My Goodness
1,554314
1,554314
$begingroup$
Thanks a lot. What if I have only fixed-width lookbehind ?
$endgroup$
– Michael
8 hours ago
1
$begingroup$
then you can't use variable-width lookbehind :) See edit.
$endgroup$
– Oh My Goodness
7 hours ago
add a comment |
$begingroup$
Thanks a lot. What if I have only fixed-width lookbehind ?
$endgroup$
– Michael
8 hours ago
1
$begingroup$
then you can't use variable-width lookbehind :) See edit.
$endgroup$
– Oh My Goodness
7 hours ago
$begingroup$
Thanks a lot. What if I have only fixed-width lookbehind ?
$endgroup$
– Michael
8 hours ago
$begingroup$
Thanks a lot. What if I have only fixed-width lookbehind ?
$endgroup$
– Michael
8 hours ago
1
1
$begingroup$
then you can't use variable-width lookbehind :) See edit.
$endgroup$
– Oh My Goodness
7 hours ago
$begingroup$
then you can't use variable-width lookbehind :) See edit.
$endgroup$
– Oh My Goodness
7 hours ago
add a comment |
Michael is a new contributor. Be nice, and check out our Code of Conduct.
Michael is a new contributor. Be nice, and check out our Code of Conduct.
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