Regex to select latest expression in math formula to change sign
I want to have a regex that can detect last math expression in order to change sign of that expression for example :
5 --> -5
-5 --> 5
5+2*cos(10) --> 5-2*cos(10)
5-cos(10+2) --> 5+cos(10+2)
I still couldn't create any regex that can match last expression. I created this regex (+[(cos|sin|tan)])+(.*[0-9]*.) but it only select the last expression if there is a sin/cos or tan.
java regex kotlin
asked Nov 15 '18 at 14:49
AndroLifeAndroLife
4961821
|
show 1 more comment
I want to have a regex that can detect last math expression in order to change sign of that expression for example :
5 --> -5
-5 --> 5
5+2*cos(10) --> 5-2*cos(10)
5-cos(10+2) --> 5+cos(10+2)
I still couldn't create any regex that can match last expression. I created this regex (+[(cos|sin|tan)])+(.*[0-9]*.) but it only select the last expression if there is a sin/cos or tan.
java regex kotlin
asked Nov 15 '18 at 14:49
AndroLifeAndroLife
4961821
5
I think that regular expressions won't solve the whole problem. You need to build a tree repesenting all the operations to choose the last one.
– mrzasa
Nov 15 '18 at 14:52
hmm okay thank you. I thought maybe I'm missing some feature of regex that might help.
– AndroLife
Nov 15 '18 at 15:05
1
It will be a crazy thing to do, but the only regex way I see is to build a regex with alternatives matching and capturing various contexts and in the match evaluator part analyze the match structure and replace accordingly. A regex that probably handles all contexts is(?:cos|sin|tan)([^()]*)|^(-)|^(d)|([-+])
– Wiktor Stribiżew
Nov 15 '18 at 15:53
@WiktorStribiżew thanks I'm not really obliged to follow regex I will try tree parsing.
– AndroLife
Nov 15 '18 at 15:59
Why regex? You can sort and take the last entry.
– Dominique
Nov 15 '18 at 16:08
|
show 1 more comment
I want to have a regex that can detect last math expression in order to change sign of that expression for example :
5 --> -5
-5 --> 5
5+2*cos(10) --> 5-2*cos(10)
5-cos(10+2) --> 5+cos(10+2)
I still couldn't create any regex that can match last expression. I created this regex (+[(cos|sin|tan)])+(.*[0-9]*.) but it only select the last expression if there is a sin/cos or tan.
java regex kotlin
asked Nov 15 '18 at 14:49
AndroLifeAndroLife
4961821
I want to have a regex that can detect last math expression in order to change sign of that expression for example :
5 --> -5
-5 --> 5
5+2*cos(10) --> 5-2*cos(10)
5-cos(10+2) --> 5+cos(10+2)
I still couldn't create any regex that can match last expression. I created this regex (+[(cos|sin|tan)])+(.*[0-9]*.) but it only select the last expression if there is a sin/cos or tan.
java regex kotlin
java regex kotlin
asked Nov 15 '18 at 14:49
AndroLifeAndroLife
4961821
asked Nov 15 '18 at 14:49
AndroLifeAndroLife
4961821
asked Nov 15 '18 at 14:49
AndroLifeAndroLife
4961821
asked Nov 15 '18 at 14:49
AndroLifeAndroLife
4961821
asked Nov 15 '18 at 14:49
AndroLifeAndroLife
4961821
4961821
5
I think that regular expressions won't solve the whole problem. You need to build a tree repesenting all the operations to choose the last one.
– mrzasa
Nov 15 '18 at 14:52
hmm okay thank you. I thought maybe I'm missing some feature of regex that might help.
– AndroLife
Nov 15 '18 at 15:05
1
It will be a crazy thing to do, but the only regex way I see is to build a regex with alternatives matching and capturing various contexts and in the match evaluator part analyze the match structure and replace accordingly. A regex that probably handles all contexts is(?:cos|sin|tan)([^()]*)|^(-)|^(d)|([-+])
– Wiktor Stribiżew
Nov 15 '18 at 15:53
@WiktorStribiżew thanks I'm not really obliged to follow regex I will try tree parsing.
– AndroLife
Nov 15 '18 at 15:59
Why regex? You can sort and take the last entry.
– Dominique
Nov 15 '18 at 16:08
|
show 1 more comment
5
I think that regular expressions won't solve the whole problem. You need to build a tree repesenting all the operations to choose the last one.
– mrzasa
Nov 15 '18 at 14:52
hmm okay thank you. I thought maybe I'm missing some feature of regex that might help.
– AndroLife
Nov 15 '18 at 15:05
1
It will be a crazy thing to do, but the only regex way I see is to build a regex with alternatives matching and capturing various contexts and in the match evaluator part analyze the match structure and replace accordingly. A regex that probably handles all contexts is(?:cos|sin|tan)([^()]*)|^(-)|^(d)|([-+])
– Wiktor Stribiżew
Nov 15 '18 at 15:53
@WiktorStribiżew thanks I'm not really obliged to follow regex I will try tree parsing.
– AndroLife
Nov 15 '18 at 15:59
Why regex? You can sort and take the last entry.
– Dominique
Nov 15 '18 at 16:08
5
5
I think that regular expressions won't solve the whole problem. You need to build a tree repesenting all the operations to choose the last one.
– mrzasa
Nov 15 '18 at 14:52
I think that regular expressions won't solve the whole problem. You need to build a tree repesenting all the operations to choose the last one.
– mrzasa
Nov 15 '18 at 14:52
hmm okay thank you. I thought maybe I'm missing some feature of regex that might help.
– AndroLife
Nov 15 '18 at 15:05
hmm okay thank you. I thought maybe I'm missing some feature of regex that might help.
– AndroLife
Nov 15 '18 at 15:05
1
1
It will be a crazy thing to do, but the only regex way I see is to build a regex with alternatives matching and capturing various contexts and in the match evaluator part analyze the match structure and replace accordingly. A regex that probably handles all contexts is
(?:cos|sin|tan)([^()]*)|^(-)|^(d)|([-+])– Wiktor Stribiżew
Nov 15 '18 at 15:53
It will be a crazy thing to do, but the only regex way I see is to build a regex with alternatives matching and capturing various contexts and in the match evaluator part analyze the match structure and replace accordingly. A regex that probably handles all contexts is
(?:cos|sin|tan)([^()]*)|^(-)|^(d)|([-+])– Wiktor Stribiżew
Nov 15 '18 at 15:53
@WiktorStribiżew thanks I'm not really obliged to follow regex I will try tree parsing.
– AndroLife
Nov 15 '18 at 15:59
@WiktorStribiżew thanks I'm not really obliged to follow regex I will try tree parsing.
– AndroLife
Nov 15 '18 at 15:59
Why regex? You can sort and take the last entry.
– Dominique
Nov 15 '18 at 16:08
Why regex? You can sort and take the last entry.
– Dominique
Nov 15 '18 at 16:08
|
show 1 more comment
1 Answer
1
active
oldest
votes
Sorry for being (incredibly) late to the party, but here's my solution:
String str = "5*10/2+cos(54/90)", regex = "(\+|-)(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$)";
Pattern pat = Pattern.compile(regex);
Matcher m = pat.matcher(str);
String r = "";
if(m.find())
{
r = m.group(1).equals("+")?"-":"+";
}
str = str.replaceAll(regex, r);
System.out.println(str);
I'm using BlueJ as an IDE, btw.
Here's a live demo: https://regex101.com/r/3EM9Ix/1
EXPLANATION
(\+|-) selects the desired operator, '+' or '-'
(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$) is the regex that checks if the operator is followed by either a function which has letters in it or just some more digits
answered Jan 13 at 19:48
Robo MopRobo Mop
1,9061517
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Sorry for being (incredibly) late to the party, but here's my solution:
String str = "5*10/2+cos(54/90)", regex = "(\+|-)(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$)";
Pattern pat = Pattern.compile(regex);
Matcher m = pat.matcher(str);
String r = "";
if(m.find())
{
r = m.group(1).equals("+")?"-":"+";
}
str = str.replaceAll(regex, r);
System.out.println(str);
I'm using BlueJ as an IDE, btw.
Here's a live demo: https://regex101.com/r/3EM9Ix/1
EXPLANATION
(\+|-) selects the desired operator, '+' or '-'
(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$) is the regex that checks if the operator is followed by either a function which has letters in it or just some more digits
answered Jan 13 at 19:48
Robo MopRobo Mop
1,9061517
add a comment |
Sorry for being (incredibly) late to the party, but here's my solution:
String str = "5*10/2+cos(54/90)", regex = "(\+|-)(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$)";
Pattern pat = Pattern.compile(regex);
Matcher m = pat.matcher(str);
String r = "";
if(m.find())
{
r = m.group(1).equals("+")?"-":"+";
}
str = str.replaceAll(regex, r);
System.out.println(str);
I'm using BlueJ as an IDE, btw.
Here's a live demo: https://regex101.com/r/3EM9Ix/1
EXPLANATION
(\+|-) selects the desired operator, '+' or '-'
(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$) is the regex that checks if the operator is followed by either a function which has letters in it or just some more digits
answered Jan 13 at 19:48
Robo MopRobo Mop
1,9061517
add a comment |
Sorry for being (incredibly) late to the party, but here's my solution:
String str = "5*10/2+cos(54/90)", regex = "(\+|-)(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$)";
Pattern pat = Pattern.compile(regex);
Matcher m = pat.matcher(str);
String r = "";
if(m.find())
{
r = m.group(1).equals("+")?"-":"+";
}
str = str.replaceAll(regex, r);
System.out.println(str);
I'm using BlueJ as an IDE, btw.
Here's a live demo: https://regex101.com/r/3EM9Ix/1
EXPLANATION
(\+|-) selects the desired operator, '+' or '-'
(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$) is the regex that checks if the operator is followed by either a function which has letters in it or just some more digits
answered Jan 13 at 19:48
Robo MopRobo Mop
1,9061517
Sorry for being (incredibly) late to the party, but here's my solution:
String str = "5*10/2+cos(54/90)", regex = "(\+|-)(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$)";
Pattern pat = Pattern.compile(regex);
Matcher m = pat.matcher(str);
String r = "";
if(m.find())
{
r = m.group(1).equals("+")?"-":"+";
}
str = str.replaceAll(regex, r);
System.out.println(str);
I'm using BlueJ as an IDE, btw.
Here's a live demo: https://regex101.com/r/3EM9Ix/1
EXPLANATION
(\+|-) selects the desired operator, '+' or '-'
(?=(?:[a-zA-Z]*\(.*?\))|[0-9^*/]+$) is the regex that checks if the operator is followed by either a function which has letters in it or just some more digits
answered Jan 13 at 19:48
Robo MopRobo Mop
1,9061517
answered Jan 13 at 19:48
Robo MopRobo Mop
1,9061517
answered Jan 13 at 19:48
Robo MopRobo Mop
1,9061517
answered Jan 13 at 19:48
Robo MopRobo Mop
1,9061517
1,9061517
add a comment |
add a comment |
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5
I think that regular expressions won't solve the whole problem. You need to build a tree repesenting all the operations to choose the last one.
– mrzasa
Nov 15 '18 at 14:52
hmm okay thank you. I thought maybe I'm missing some feature of regex that might help.
– AndroLife
Nov 15 '18 at 15:05
1
It will be a crazy thing to do, but the only regex way I see is to build a regex with alternatives matching and capturing various contexts and in the match evaluator part analyze the match structure and replace accordingly. A regex that probably handles all contexts is
(?:cos|sin|tan)([^()]*)|^(-)|^(d)|([-+])– Wiktor Stribiżew
Nov 15 '18 at 15:53
@WiktorStribiżew thanks I'm not really obliged to follow regex I will try tree parsing.
– AndroLife
Nov 15 '18 at 15:59
Why regex? You can sort and take the last entry.
– Dominique
Nov 15 '18 at 16:08