We Keep Coding

Find integers and floats in SQL query string using Python and regex

I am working on a Python function that parses a string representing a SQL query and returns the numbers (both integers and floats). I need those to highlight the numbers in the GUI.
I use https://regex101.com/ to test the regular expressions I build and I have almost got it except when number is a part of a column name in the SQL query.
[-+]?[0-9]*\.?[0-9]+([eE][-+]?[0-9]+)?
would include even pop1990 in 220, pop1990 in (5, 100, 7.8,25;) which I want to avoid. It looks as I may need to use negations using ^ but not sure how it would work.
When searching for numbers, how do I exclude those cases when number comes right after a word character (\w) but still match when it comes before or after (, ,, ; and so forth?

Maybe this is what you're looking for:
https://regex101.com/r/BgEP7C/1
The regex is (?<=[^\w])[\d\.]+.
(?<=[^\w]) it's a positive lookbehind; it checks if what's behind the number is NOT a \w, but it doesn't add it to the match.
[\d\.]+ matches multiple numbers and . for the decimal point.
Updated so it works with +, - and e:
Link: https://regex101.com/r/BgEP7C/5
Regex: (?i)(?<=[^\w])[-+]?[\d\.]+(e[-+]?\d+)?
REQUESTED EDIT
The original version doesn't work in Python beacause of the (e[-+]?\d+)? part.
A version that workds in Python: (?i)(?<=[^\w])[-+]?[\d\.]+e?[+-]?\d*

How can I extract data from a string with no pattern?

How can I extract 117, 0.049, 207 in a string?
particulate 117㎍/㎥bad(81~150),ozone 0.049ppmaverage(0.041~0.080),overall air quality 207bad(151~250)

Parsing unstructured text is messy: You can get quick results with regular expressions as seen here:
input='particulate 117㎍/㎥bad(81~150),ozone 0.049ppmaverage(0.041~0.080),overall air quality 207bad(151~250)'
import re
input=re.sub(r'\(.*?\)','',input)
results=re.findall(r'[\d.]+',input)
print(results) # this prints ['117', '0.049', '207']
... But to get always the results you want can be difficult.
Let's discuss the solution step by step...
First of all, your input contains numbers inside brackets -- and you don't want them. So, we first need to remove the brackets with a regular expression substitution:
input=re.sub(r'\(.*?\)','',input)
# now input is:
# particulate 117㎍/㎥bad,ozone 0.049ppmaverage,overall air quality 207bad
This substitution searches for sub-strings starting with an opening bracket '(' and ending with a closing bracket ')' and replaces them by an empty string. In writing this expression, we need to take into account a few details:
Brackets have a special meaning in regular expressions. To refer to actual brackets in your input, we need to escape them in the pattern and write '(' instead of '('.
Normally the pattern r'(.*)' would take the first opening bracket and all text up to the last closing bracket in our input. This is too greedy. We add the question-mark after the star to make the expression non-greedy. * Still, if the brackets in your input don't match up, you may get wrong results.
As the second step, we want to pick out numbers from the remaining input. Your numbers may contain decimal point, so we need to allow this as well in the regular expression. But matching numbers precisely with regular expressions is tricky. Here are valid numbers (for some definitions of valid) that our solution doesn't pick up:
-1.32 1.04e4 -3.14e-23
Here is a string that our pattern picks up as numbers --- but you may not want them:
10.24.12.123
All of this can be fixed --- but the pattern will be more complex. And you have to decide precisely what you want to get and what you don't want to get.
Here is a link to the Python regular expression documentation.

regex- capturing text between matches

In the following text, I try to match a number followed by ")" and number followed by a period. I am trying to retrieve the text between the matches.
Example:
"1) there is a dsfsdfsd and 2) there is another one and 3) yet another
case"
so I am trying to output: ["there is a dsfsdfsd and", "there is another one and", yet another case"]
I've used this regex: (?:\d)|\d.)
Adding a .* at the end matches the entire string, I only want it to match the words between
also in this string:
"we will give 4. there needs to be another option and 6.99 USD is a
bit amount"
I want to only match the 4. and not the 6.99
Any pointers will be appreciated. Thank you. r

tldr
Regular expressions are tricky beasts and you should avoid them if at all possible.
If you can't avoid them, then make sure you have lots of test cases for all the edge cases that can occur.
Build up your regular expression slowly and systematically, testing your assumptions at every step.
If this code will go intro production, then please write unit tests that explain the thinking process to the poor soul who has to maintain it one day
The long version
Regular expressions are finicky. Your best approach may be to solve the problem a different way.
For example, your language might have a library function that allows you to split up strings using a regular expression to define what comes between the numbers. That will let you get away with writing a simpler regex to match the numbers and brackets/dots.
If you still decide to use regular expressions, then you need to be very structured about how you build up your regular expressions. It's extremely easy to miss edge cases.
So let's break this down piece by piece...
Set up a test environment for quickly experimenting with your regex.
There are lots of options here, depending on your programming language and OS. Ones I sometimes use are:
a Powershell window for testing .Net regexes (NB: the cli gives you a history of past attempts, so you can go back a few steps if you mess things up too badly)
a Python console for testing Python regexes (which are slightly different to .Net regexes in their syntax for named capture groups).
an html page with JavaScript to test the regex
an online or desktop regex tool (I still use the ancient Regular Expression Workbench from Eric Gunnerson, but I'm sure there are better alternatives these days)
Since you didn't specify a language or regex version, I'll assume .Net regular expressions
Create a single test string for testing a wider variety of options.
Your goal is to include as many edge cases as you can think of. Here's what I would use: "ab 1. there is a dsfsdfsd costing $6.99 and 2) there is another one and 3. yet another case 4)5) 6)10."
Note that I've added a few extra cases you didn't mention:
empty strings between two round bracket numbers: "4)" and "5)"
white space string between two round bracket numbers: "5)" and "6)"
empty strings between a round bracket number and a dotted number: "6)" and "10."
empty string after the dotted number "10." at the end of the string
random text and empty space, which should be ignored, before the first number
I'm going to make a few assumptions here, which you will need to vary based on your actual requirements:
You DO want to capture the white space after the dot or round bracket.
You DO want to capture the white space before the next dotted number or round bracket number.
You might have numbers that go beyond 9, so I've included "10" in the test cases.
You want to capture empty strings at the end e.g. after the "10."
NOTES:
Thinking through this test case forces you to be more rigorous about your requirements.
It will also help you be more efficient while you are manually testing your regular expression.
HOWEVER, this is assuming you aren't following a TDD approach. If you are, then you should probably do things a little differently... create unit tests for each scenario separately and get the regex working incrementally.
This test string doesn't cover all cases. For example, there are no newline or tab characters in the test string. Also it can't test for an empty string following a round bracket number at the very end.
First get a regex working that just captures the round brackets and dotted brackets.
Don't worry about the $6.99 edge case yet.
Drop the "(?:" non-capturing group syntax from your regex for now: "\d)|\d."
This doesn't even parse, because you have an unescaped round bracket.
The revised string is "\d\)|\d.", which parses, but which also matches "99" which you probably weren't expecting. That's because you forgot to escape the "."
The revised string is "\d\)|\d\.". This no longer matches "99", but it now matches "0." at the end instead of "10.". That's because it assumes that numbers will be single digit only.
The following string seems to work: "\d+\)|\d+\."
Time to deal with that pesky "$6.99" now...
Modify the regex so that it doesn't capture a floating point number.
You need to use a negative look ahead pattern to prevent a digit being after the decimal point.
Result: "\d+\)|\d+\.(?!\d)"
Count how many matches this produces. You're going to use this number for checking later results.
Hint: Save the regex pattern somewhere. You want to be able to go back to it any time you mess up your regex pattern beyond repair.
If you found a string splitting function, then you should use it now and avoid the complexity that follows. [I've included an example of this at the end.]
Simple is better, but I'm going to continue with the longer solution in the interests of showing an approach to staying in control of regex'es that start getting horribly complicated
Decide how to exclude that pattern
You used the non-capture group pattern in your question i.e. "(?:"
That approach can work. But it's a bit cumbersome, because you need to have a capturing group after it that you will look for instead.
It would be much nicer if your entire pattern matched what you are looking for.
So wrap the number pattern inside a zero-width positive look behind pattern (if your language supports it) i.e. "(?<=".
This checks for the pattern, but doesn't include it in what gets captured.
So now your regex looks like this: "(?<=\d+\)|\d+\.(?!\d))"
Test it!
It might seem silly to test this on its own - all the matches are empty strings.
Do it anyway. You want to sanity check every step of the way.
Make sure that it still produces the same number of matches as in step 4.
Decide how to match the text in between the numbers.
You rightly mention that ".*" will match the entire string, not just the parts in between.
There's a neat trick that allows you to reuse the pattern from step 5 to get the text in between.
Start by just matching the next character
The trick is that you want to match any character unless it's the start of the next number
That sounds like a negative look ahead pattern again: "(?!"
Let X be the pattern you saved in step 4. Matching a single character will look like this: "(?!X)."
You want to match lots of those characters. So put that pattern into a non-capturing group and repeat it: "(?:(?!X).)*"
This assumes you want to capture empty text.
If you're not, then change the "*" to a "+".
Hint: This is such a common pattern that you will want to reuse it in future pasting in different patterns in place of X
I used a non-capturing group instead of a normal group so that you can also embed this pattern in regexes where you do care about the capturing groups
Resulting pattern: "(?:(?!\d+\)|\d+\.(?!\d)).)*"
I suggest testing this pattern on its own to see what it does
Now put parts 5 and 7 together: "(?<=\d+\)|\d+\.(?!\d))(?:(?!\d+\)|\d+\.(?!\d)).)*"
Test it!
Unit tests!
If this is going into production, then please write lots of unit tests that will explain each step of this thought process
Have pity on the poor soul who has to maintain your regex in future!
By rights that person should be you
I suggest putting a note in your calendar to return to this code in 6 months' time and make sure you can still understand it from the unit tests alone!
Refactor
In six months' time, if you can't understand the code any more, use your newfound insight (and incentive) to solve the problem without using regular expressions (or only very simple ones)
Addendum
As an example of using a string splitting function to get away with a simpler regex, here's a solution in Powershell:
$string = 'ab 1. there is a dsfsdfsd costing $6.99 and 2) there is another one and 3. yet another case 4)5) 6)10.'
$pattern = [regex] '\d+\)|\d+\.(?!\d)'
$string -split $pattern | select-object -skip 1

Judging by the task you have, it might be easier to match the delimiters and use re.split (as also pointed out by bobblebubble in the comments).
I dsuggest a mere
\d+[.)]\B\s*
See it in action (demo)
It matches 1 or more digits, then a . or a ), then it makes sure there is no word letter (digit, letter or underscore) after it and then matches zero or more whitespace.
Python demo:
import re
rx = r'\d+[.)]\B\s*'
test_str = "1) there is a dsfsdfsd and 2) there is another one and 3) yet another case\n\"we will give 4. there needs to be another option and 6.99 USD is a bit amount"
print([x for x in re.split(rx,test_str) if x])

Try the following regex with the g modifier:
([A-Za-z\s\-_]+|\d(?!(\)|\.)\D)|\.\d)
Example: https://regex101.com/r/kB1xI0/3
[A-Za-z\s\-_]+ automatically matches all alphabetical characters + whitespace
\d(?!(\)|\.)\D) match any numeric sequence of digits not followed by a closing parenthesis ) or decimal value (.99)
\.\d match any period followed by numeric digit.

I used this pattern:
(?<=\d.\s)(.*?)(?=\d.\s)
demo
This looks for the contents between any digit, any character, then a space.
Edit: Updated pattern to handle the currency issue and line ends better:
This is with flag 'g'
(?<=[0-9].\s)(.*?)(?=\s[0-9].\s|\n|\r)
Demo 2

import re
s = "1) there is a dsfsdfsd and 2) there is another one and 3) yet another case"
s1 = "we will give 4. there needs to be another option and 6.99 USD is a bit amount"
regex = re.compile("\d\)\s.*?|\s\d\.\D.*?")
print ([x for x in regex.split(s) if x])
print regex.split(s1)
Output:
['there is a dsfsdfsd and ', 'there is another one and ', 'yet another case']
['we will give', 'there needs to be another option and 6.99 USD is a bit amount']

parsing string with specific name in python

i have string like this
<name:john student male age=23 subject=\computer\sience_{20092973}>
i am confused ":","="
i want to parsing this string!
so i want to split to list like this
name:john
job:student
sex:male
age:23
subject:{20092973}
parsing string with specific name(name, job, sex.. etc) in python
i already searching... but i can't find.. sorry..
how can i this?
thank you.

It's generally a good idea to give more than one example of the strings you're trying to parse. But I'll take a guess. It looks like your format is pretty simple, and primarily whitespace-separated. It's simple enough that using regular expressions should work, like this, where line_to_parse is the string you want to parse:
import re
matchval = re.match("<name:(\S+)\s+(\S+)\s+(\S+)\s+age=(\S+)\s+subject=[^\{]*(\{\S+\})", line_to_parse)
matchgroups = matchval.groups()
Now matchgroups will be a tuple of the values you want. It should be trivial for you to take those and get them into the desired format.
If you want to do many of these, it may be worth compiling the regular expression; take a look at the re documentation for more on this.
As for the way the expression works: I won't go into regular expressions in general (that's what the re docs are for) but in this case, we want to get a bunch of strings that don't have any whitespace in them, and have whitespace between them, and we want to do something odd with the subject, ignoring all the text except the part between { and }.
Each "(...)" in the expression saves whatever is inside it as a group. Each "\S+" stands for one or more ("+") characters that aren't whitespace ("\S"), so "(\S+)" will match and save a string of length at least one that has no whitespace in it. Each "\s+" does the opposite: it has not parentheses around it, so it doesn't save what it matches, and it matches at one or more ("+") whitespace characters ("\s"). This suffices for most of what we want. At the end, though, we need to deal with the subject. "[...]" allows us to list multiple types of characters. "[^...]" is special, and matches anything that isn't in there. {, like [, (, and so on, needs to be escaped to be normal in the string, so we escape it with \, and in the end, that means "[^{]*" matches zero or more ("*") characters that aren't "{" ("[^{]"). Since "*" and "+" are "greedy", and will try to match as much as they can and still have the expression match, we now only need to deal with the last part. From what I've talked about before, it should be pretty clear what "({\S+})" does.

Extracting parenthesis with a specific format with Python

I am fairly new to python so I apologies if this is quite a novice question, but I am trying to extract text from parentheses that has specific format from a raw text file.
I have tried this with regular expressions, but please let me know if their is a better method.
To show what I want to do by example:
s = "Testing (Stackoverflow, 2013). Testing (again) (Stackoverflow, 1999)"
From this string I want a result something like:
['(Stackoverflow, 2013)', '(Stackoverflow, 1999)']
The regular expression I have tried so far is
"(\(.+[,] [0-9]{4}\))"
in conjunction with re.findall(), however this only gives me the result:
['(Stackoverflow, 2013). Testing (again) (Stackoverflow, 1999)']
So, as you may have guessed, I am trying to extract the bibliographic references from a .txt file. But I don't want to extract anything that happens to be in parentheses that is not a bibliographic reference.
Again, I apologies if this is novice, and again if there is a question like this out there already. I have searched, but no luck as yet.

Using [^()] instead of .. This will make sure there is no nested ().
>>> re.findall("(\([^()]+[,] [0-9]{4}\))", s)
['(Stackoverflow, 2013)', '(Stackoverflow, 1999)']

Assuming that you will have no nested brackets, you could use something like so: (\([^()]+?, [0-9]{4}\)). This will match any non bracket character which is within a set of parenthesis which is followed by a comma, a white space four digits and a closing parenthesis.

I would suggest something like \(\w+,\s+[0-9]{4}\). A couple changes from your original:
Match word characters (letters/numbers/underscores) instead of any character in the source name.
Match one or more space characters after the comma, instead of limiting yourself to a single literal space.