I have data like
http://www.linz.at/politik_verwaltung/32386.asp
stored in a text column. I thought a non-greedy extraction with
select substring(turl from '\..*?$') as ext from tdata
would give me .asp but instead it still ?greedely results in
.linz.at/politik_verwaltung/32386.asp
How can I only match against the last occurence of dot .?
Using Postgresql 9.3
\.[^.]*$ matches . followed by any number of non-dot characters followed by end-of-string:
# select substring('http://www.linz.at/politik_verwaltung/32386.asp'
from '\.[^.]*$');
substring
-----------
.asp
(1 row)
As for why the non-greedy quantifiers do not work here is that they still start matching as soon as possible while still trying to match as short as possible from there on.
Try this:
\.[\w]*$
Here is how it works:
all the word characters (\w), any numbers of them with *, between dot (\.) and the end of the string ($), with the last . itself.
Note: updated the answer, now will capture the strings ends with ..
Related
I need to retrieve the bolded section of the below string . This value is in a column within my Postgres database table.
SEALS_LME_TRADES_MBL_20220919_00212.csv
I tried to utilize the functions; substring, reverse, strpos but they all have limitations. It seems like regex is the best option, however I was not able to do it.
Essentially I need to substring from beginning till the second last '_'. I do not want the date and sequence number along with the file extension at the end.
The closes regex I managed to get is: ^(([^]*){4})
https://regex101.com/
This look a little wonky but how about this?
select substring ('SEALS_LME_TRADES_MBL_20220919_00212.csv', '^(.+)_[^_]+_[^_]+')
Translation
^ from the beginning
(.+) any characters (capture and return this value), followed by
_ an underscore, followed by
[^_]+ one or more non-underscores, followed by
_ an underscore, followed by
[^_]+ one or more non-underscores
Regex greediness will cause any incidental underscores to be captured in the initial string.
Technically speaking the last portion (one or more non-underscores) can probably be omitted.
I have two types of URL's which I would need to clean, they look like this:
["//xxx.com/se/something?SE_{ifmobile:MB}{ifnotmobile:DT}_A_B_C_D_E_F_G_H"]
["//www.xxx.com/se/car?p_color_car=White?SE_{ifmobile:MB}{ifnotmobile:DT}_A_B_C_D_E_F_G_H"]
The outcome I want is;
SE_{ifmobile:MB}{ifnotmobile:DT}_A_B_C_D_E_F_G_H"
I want to remove the brackets and everything up to SE, the URLS differ so I want to remove:
First URL
["//xxx.com/se/something?
Second URL:
["//www.xxx.com/se/car?p_color_car=White?
I can't get my head around it,I've tried this .*\/ . But it will still keep strings I don't want such as:
(1 url) =
something?
(2 url) car?p_color_car=White?
You can use
regexp_replace(FinalUrls, r'.*\?|"\]$', '')
See the regex demo
Details
.*\? - any zero or more chars other than line breakchars, as many as possible and then ? char
| - or
"\]$ - a "] substring at the end of the string.
Mind the regexp_replace syntax, you can't omit the replacement argument, see reference:
REGEXP_REPLACE(value, regexp, replacement)
Returns a STRING where all substrings of value that match regular
expression regexp are replaced with replacement.
You can use backslashed-escaped digits (\1 to \9) within the
replacement argument to insert text matching the corresponding
parenthesized group in the regexp pattern. Use \0 to refer to the
entire matching text.
I am trying to extract a item_subtype field from an URL.
This regex works fine in the to get the first item item_type
SELECT REGEXP_EXTRACT('info?item_type=icecream&item_subtype=chocolate/cookies%20cream,vanilla&page=1', r'item_type=(\w+)')
but what is the correct regex to get everything starting from 'chocolate' all the way to before the '&page1'
I have tried this, but can't seem to get it to work to go further
SELECT REGEXP_EXTRACT('info?item_type=icecream&item_subtype=chocolate/cookies%20cream,vanilla&page=1', r'item_subtype=(\w+[^Z])')
basically, I want to extract 'chocolate/cookies%20cream,vanilla'
In your case, \w+ only matches one or more letters, digits or underscores. Your expected values may contain other characters, too.
You may use
SELECT REGEXP_EXTRACT('info?item_type=icecream&item_subtype=chocolate/cookies%20cream,vanilla&page=1', r'item_subtype=([^&]+)')
See the regex demo.
Notes:
item_subtype= - this string is matched as a literal char sequence
([^&]+) - a Capturing group 1 that matches and captures one or more chars other than & into a separate memory buffer that is returned by REGEXP_EXTRACT function.
Have strings containing 'q_' which I want to extract everything that comes after it. Some rows contain occurrence of q_ which I want everything that occurs after it. Example values in the column are:
prod-q_cat_trait_cat_social_issue
_prod-q_body_modification_graffiti
event_tickets
dappled_grey
_prod-q_cat_tech_support
What is wrong with my regular expression as I'm trying to remove the trailing '_' after q.
REGEXP_EXTRACT(queue_id, '[^q_]+$')
Is just returning
issue
I've also tried the split method:
SPLIT(queue_id, 'q_')[OFFSET(2)]
But this returns
Array index 2 is out of bounds (overflow)
Any suggestions. Thanks! (I am using Google Cloud SQL)
Using a capturing group, you may extract all after the first q_ with:
REGEXP_EXTRACT(queue_id, 'q_(.*)')
You may extract all after the last q_ with:
REGEXP_EXTRACT(queue_id, '.*q_(.*)')
See the regex demo #1 and regex demo #2.
Here, q_ finds the first occurrence of q_ and (.*) grabs the rest of the line into Group 1, and this is the value returned by REGEXP_EXTRACT. .* matches any 0+ chars other than line break chars as many as possible, that is why the second regex will start capturing the rest of the line after the last occurrence of q_.
Google Cloud SQL uses MySQL. I think the simplest method is substring_index():
select substring_index(queue_id, '-q_', -1)
Can you try this : q_([^q_]+)$? You'll have what you want in the first group.
Edit: this one match all the cases > (?(?<=-q_).*|^((?!-q_).)*$)
I am trying to construct a regular expression to find the text of the following variations.
NSLocalizedString(#"TEXT")
NSLocalizedStringFromTable(#"TEXT")
NSLocalizedStringWithDefaultValue(#"TEXT")
...
The goal is to extract TEXT. I have been able to construct a regex for each individual function or macro, e.g., (?<=NSLocalizedString)\(#"(.*?)". However, I am looking for a solution that does the job no matter what the name of the function as long as it starts with NSLocalizedString.
I assumed it was as simple as (?<=NSLocalizedString\w+)\(#"(.*?)", but that does't seem to do the trick.
How about this one?
/NSLocalizedString\w*\(#"(.*)"\)/
Explanation:
NSLocalizedString 'NSLocalizedString'
\w+ word characters (a-z, A-Z, 0-9, _) (0 or
more times (matching the most amount
possible))
\( '('
#" '#"'
( group and capture to \1:
.* any character except \n (0 or more times
(matching the most amount possible))
) end of \1
" '"'
\) ')'
The only reason your regex doesn't work is because the regex engine doesn't support variable length lookbehinds. The (?<=NSLocalizedString\w+) is variable length so can't be used.
Firstly it needs to be \w* not \w+, to allow your first example string to match.
If you move the \w* outside the lookbehind (?<=NSLocalizedString)\w* it will work just fine.
Alternatively, since you have to use a capturing group to grab the text value anyway, theres no need for the lookbehind at all. Change the (?<= to a (?: and it becomes a non-capturing group (which can be variable length), and then just grab your text value from group 1.
Your attempt was:
(?<=NSLocalizedString\w+)\(#"(.*?)"
Both of these minor changes should make it work:
(?<=NSLocalizedString)\w*\(#"(.*?)"
(?:NSLocalizedString\w*)\(#"(.*?)"
The following is actually not supported in Objective-C:
The solution that will extract exactly TEXT without using any groups is:
NSLocalizedString\w*\(#"\K[^"]*
It avoids the need to use a negative lookbehind (which can't be used for reasons I explain below) by using the \K modifier, which chops off anything before it from the match.