I'm using a string to store a quadratic equation and then resolve it via quadratic formula.
So i require a regex for removing elements like x and/or x[^2], but i really i don't know how to create a regex unless i use replace for each symbol/letter/number i want to remove.
Ex:
Input: 2x^2+4x+6
Output: 2 4 6
Here is a regex that matches a quadratic polynomial:
^(?:([+-]?\d+)x\^2)?(?:([+-]?\d+)x)?([+-]?\d+)?$
Group 1 is the coefficient of x^2, Group 2 is the coefficient of x, Group 3 is the constant. A group with an empty string means it's a 1. You just get those groups and plug them into the quadratic formula. Remember to remove all whitespace from the string before using the regex.
Note that this regex matches things like 6x3 and interprets it as 6x+3.
Demo
Related
I'm using an online tool to create contests. In order to send prizes, there's a form in there asking for user information (first name, last name, address,... etc).
There's an option to use regular expressions to validate the data entered in this form.
I'm struggling with the regular expression to put for the street number (I'm located in Belgium).
A street number can be the following:
1234
1234a
1234a12
begins with a number (max 4 digits)
can have letters as well (max 2 char)
Can have numbers after the letter(s) (max3)
I came up with the following expression:
^([0-9]{1,4})([A-Za-z]{1,2})?([0-9]{1,3})?$
But the problem is that as letters and second part of numbers are optional, it allows to enter numbers with up to 8 digits, which is not optimal.
1234 (first group)(no letters in the second group) 5678 (third group)
If one of you can tip me on how to achieve the expected result, it would be greatly appreciated !
You might use this regex:
^\d{1,4}([a-zA-Z]{1,2}\d{1,3}|[a-zA-Z]{1,2}|)$
where:
\d{1,4} - 1-4 digits
([a-zA-Z]{1,2}\d{1,3}|[a-zA-Z]{1,2}|) - optional group, which can be
[a-zA-Z]{1,2}\d{1,3} - 1-2 letters + 1-3 digits
or
[a-zA-Z]{1,2} - 1-2 letters
or
empty
\d{0,4}[a-zA-Z]{0,2}\d{0,3}
\d{0,4} The first groupe matches a number with 4 digits max
[a-zA-Z]{0,2} The second groupe matches a char with 2 digit in max
\d{0,3} The first groupe matches a number with 3 digits max
You have to keep the last two groups together, not allowing the last one to be present, if the second isn't, e.g.
^\d{1,4}(?:[a-zA-z]{1,2}\d{0,3})?$
or a little less optimized (but showing the approach a bit better)
^\d{1,4}(?:[a-zA-z]{1,2}(?:\d{1,3})?)?$
As you are using this for a validation I assumed that you don't need the capturing groups and replaced them with non-capturing ones.
You might want to change the first number check to [1-9]\d{0,3} to disallow leading zeros.
Thank you so much for your answers ! I tried Sebastian's solution :
^\d{1,4}(?:[a-zA-z]{1,2}\d{0,3})?$
And it works like a charm ! I still don't really understand what the ":" stand for, but I'll try to figure it out next time i have to fiddle with Regex !
Have a nice day,
Stan
The first digit cannot be 0.
There shouldn't be other symbols before and after the number.
So:
^[1-9]\d{0,3}(?:[a-zA-Z]{1,2}\d{0,3})?$
The ?: combination means that the () construction does not create a matching substring.
Here is the regex with tests for it.
My regex currently looks like this
\b(19|20)\d{2}\b[- :][VW][0-5]{1}(?(?=[5])[0-2]{1}|[0-9]{1})
It doesn't quite do what I want as I'm trying to get this part
(?(?=[5])[0-2]{1}|[0-9]{1})
to say "If the previous number was 5 then you may only choose between 0-2, and if it's another number 0-4 then choosing between 0-9 is allowed
Currently it allowes 00-59 with an exclusion of 05,15,25,35 etc.
Essentially I want it to look like this for example 2016-W25.
You need to replace [5] with a positive lookbehind (?<=5) in order to check a char to the left of the current location:
\b(19|20)\d{2}[- :][VW][0-5](?(?=(?<=5))[0-2]|[0-9])
^^^^^
See the regex demo
Also, you may get rid of the conditional pattern at all using a mere alternation group:
\b(19|20)\d{2}[- :][VW](?:[0-4][0-9]|5[0-2])
^^^^^^^^^^^^^^^^^^^^^
See this regex demo
The (?:[0-4][0-9]|5[0-2]) matches either a digit from 0 to 4 and then any digit (see [0-4][0-9]), or (see |) a 5 followed with 0, 1 or 2 (see 5[0-2]).
NOTE: Since the number of weeks can amount to 53, the [0-2] at the end might be replaced with [0-3] to also match 53 values.
I have thousands of article descriptions containing numbers.
they look like:
ca.2760h3x1000.5DIN345x1500e34
the resulting numbers should be:
2760
1000.5
1500
h3 or 3 shall not be a result of the parsing, since h3 is a tolerance only
same for e34
DIN345 is a norm an needs to be excluded (every number with a trailing DIN or BN)
My current REGEX is:
[^hHeE]([-+]?([0-9]+\.[0-9]+|[0-9]+))
This solves everything BUT the norm. How can I get this "DIN" and "BN" treated the same way as a single character ?
Thanx, TomE
Try using this regular expression:
(?<=x)[+-]?0*[0-9]+(?:\.[0-9]+)?|[+-]?0*[0-9]+(?:\.[0-9]+)?(?=h|e)
It looks like every number in your testcase you want to match exept the first number is starting with x.This is what the first part of the regex matches. (?<=x)[+-]?0*[0-9]+(?:\.[0-9]+)?The second part of the regex matches the number until h or e. [+-]?0*[0-9]+(?:\.[0-9]+)?(?=h|e)
The two parts [+-]?0*[0-9]+(?:\.[0-9]+)? in the regex is to match the number.
If we can assume that the numbers are always going to be four digits long, you can use the regex:
(\d{4}\.\d+|\d{4})
DEMO
Depending on the language you might need to replace \d with [0-9].
I have the requirement to validate a String containing two numbers separated by a dash(-) or a comma(,). Valid values are :
23.98-34.76 or 23.98,34.76
23-34 or 23,34
5-6 or 5,6
I have the following regex which is a slight modification of the answer that I received here in SO. It is covering the 1st and 2nd case above but not the third case involving single digits only.
The modified regex String that I am using is :
(\d+\.?\d+?)([-,])(\d+\.?\d+?)
Where did my regex go wrong?
Correct regex should be like this:
(\d+(\.\d+)?)[-,](\d+(\.\d+)?)
i.e. if there is a period then it is always followed by 1 or more digits.
Otherwise in your regex it will also match strings like 123.,789.
I'm parsing a bunch of line items on an inventory list and while each line describes something similar, the text format was not standardized. I'm been working on a regex pattern for the past few days but I'm not having much luck with getting a pattern that can match all of my test scenarios. I hoping that someone with a lot more regex experience might be able to point out a few errors in the the pattern
Pattern To Match the palette number: \([Pp]alette [No\.\s]?#?(.*?)\),
1. Warehouse A, (Palette #91L41)
# Match Result Correct: 91L41
2. Warehouse B Palette No. 214
# Match Result Incorrect: no match
3. Warehouse Lot Storage C (Palette No. 9),
# Match Result Incorrect: o. 9 //I don't quite understand why it matches the o
4. Store Location D of Palette (Palette #1),
# Match Result Correct: 1
5. Store Location E of Palette, Empty, lot #45,
# Match Result Incorrect: no match
I've also tried to make the parenthesis optional so that it will match examples 2 and 5 but it's too greedy and included the previously mentioned lot word
Anything in brackets causes the engine to look for ONE of the provided characters. Your pattern successfully matches, for example, strings like: Palette Nabcdefg
To indicate one of different options, you'll need to use paranthesis. What you're actually looking for should look something like this: [Pp]alette (No\.?\s?|#)?(\d+?)
Though it seems highly ineffective to not standardize the pattern. Your last case for example could be completely incompatible since it seems to be capable of containing possibly any kind of input.
A little bit of explanation on matching your patterns with regular expressions. You really don't need to look for and match your parentheses ( .. ) in this case.
Let's say we want to just find any string with the word Palette that is followed with whitespace and the # symbol and capture the Palette sequence from it.
You could simply just use the following:
[Pp]alette\s+#([A-Z0-9]+)
This will result in capturing 91L41 and 1 from the matched patterns
1. Warehouse A, (Palette #91L41)
4. Store Location D of Palette (Palette #1)
Now say we want to find any string that has Palette, followed by whitespace and either a # symbol or No.
We can use a Non-capturing group for this. Non-capturing parentheses group the regex so you can apply regex operators, but do not capture anything.
So we could do something like:
[Pp]alette\s+(?:No[ .]+|#)([A-Z0-9]+)
Now this results in matching the following strings and capturing 91L41, 214, 9 and 1
1. Warehouse A, (Palette #91L41)
2. Warehouse B Palette No. 214
3. Warehouse Lot Storage C (Palette No. 9)
4. Store Location D of Palette (Palette #1)
And last if you want to match all the following strings and capture the Palette sequence.
[Pp]alette[\w, ]+(?:No[ .]+|#)([A-Z0-9]+)
See working demo and an explanation on this regular expression.
Everyone has a different way of using regular expressions, this is just one of many ways you can simply understand and accomplish this.
This should work for your case:
[Pp]alette.*?(?:No\.?|#)\s*(\w+)
This will search following types of patterns:
[Pp]alette{any_characters}No.{optonal_spaces}(alphanumeric)
[Pp]alette{any_characters}No{optonal_spaces}(alphanumeric)
[Pp]alette{any_characters}#{optonal_spaces}(alphanumeric)
Check it in action here
MATCH 1
1. [26-31] `91L41`
MATCH 2
1. [60-63] `214`
MATCH 3
1. [104-105] `9`
MATCH 4
1. [148-149] `1`
MATCH 5
1. [195-197] `45`