I have a regex where I want to find all of the empty strings in a SQL statement (and replace them with NULL).
So that this:
INSERT INTO sometable (F1,F2,F3,F4,F5) VALUES ('','',"xxx's",'','')
Becomes this:
INSERT INTO sometable (F1,F2,F3,F4,F5) VALUES (NULL,NULL,"xxx's",NULL,NULL)
I want to be sure that I am only updating the VALUES() array and this is what I cam up with however this only matches the last occurance of '' and not the other 3 empty strings.
/VALUES.*\(.*('').*\)/
Is this possible ?
Wow. this looks dangerous lol.
I think this would work:
myString.replace(/VALUES.*\(.*\)/, function (values) {
return values.replace(/''/g, 'null');
});
While technically still 2 regular expressions, you could make it a one liner with es6 :)
myString.replace(/VALUES.*\(.*\)/, str => str.replace(/''/g, 'null'));
Related
So i have this regex:
=([0-9A-Za-z_-]+),?
and i need have a string like:
foo=bar,pine=apple,tree,bar=bie
or
foo=bar,pine=apple,tree
or
pine=apple,tree
the regex works for cases where i only have 1 value.
but since we have comma's in the list of values for the key.
the regex just craps out and my code does half of what i want it to do but doesn't get the 2nd value.
How do i fix my regex to take both values regardless of where in the string it is?
alone, between 2 others, at the end.
i tried some stuff but couldn't figure it out.
Attempt 1:
=([0-9A-Za-z,_-]+),=?
In this case, it matches the one where it's in the middle but it fails on the others because = does not exist.
Attempt 2:
=[0-9A-Za-z_-]+([,]+[0-9A-Za-z_-]*),?
Matches too bar,pine and tree,bar for example
EDIT::
This seems to work maybe....
=('[0-9A-Za-z,_-]+'),*|=([0-9A-Za-z_-]+),*
if i use quotes for multi values..
You can split on variable names - that will leave only the values:
s := regexp.MustCompile("[^,\\s]+=").Split("foo=bar,pine=apple,tree,bar=bie", -1)
fmt.Println(s)
# => [ "bar", "apple,tree", "bie"]
Go Demo
Regex Demo
I have a list of records that are character vectors. Here's an example:
'1mil_0,1_1_1_lb200_ks_drivers_sorted.csv'
'1mil_0_1_lb100_ks_drivers_sorted.csv'
'1mil_1_1_lb2_100_100_ks_drivers_sorted.csv'
'1mil_1_1_lb100_ks_drivers_sorted.csv'
From these names I would like to extract whatever's between the two substrings 1mil_ and _ks_drivers_sorted.csv.
So in this case the output would be:
0,1_1_1_lb200
0_1_lb100
1_1_lb2_100_100
1_1_lb100
I'm using MATLAB so I thought to use regexp to do this, but I can't understand what kind of regular expression would be correct.
Or are there some other ways to do this without using regexp?
Let the data be:
x = {'1mil_0,1_1_1_lb200_ks_drivers_sorted.csv'
'1mil_0_1_lb100_ks_drivers_sorted.csv'
'1mil_1_1_lb2_100_100_ks_drivers_sorted.csv'
'1mil_1_1_lb100_ks_drivers_sorted.csv'};
You can use lookbehind and lookahead to find the two limiting substrings, and match everything in between:
result = cellfun(#(c) regexp(c, '(?<=1mil_).*(?=_ks_drivers_sorted\.csv)', 'match'), x);
Or, since the regular expression only produces one match, the following simpler alternative can be used (thanks #excaza for noticing):
result = regexp(x, '(?<=1mil_).*(?=_ks_drivers_sorted\.csv)', 'match', 'once');
In your example, either of the above gives
result =
4×1 cell array
'0,1_1_1_lb200'
'0_1_lb100'
'1_1_lb2_100_100'
'1_1_lb100'
For me the easy way to do this is just use espace or nothing to replace what you don't need in your string, and the rest is what you need.
If is a list, you can use a loop to do this.
Exemple to replace "1mil_" with "" and "_ks_drivers_sorted.csv" with ""
newChr = strrep(chr,'1mil_','')
newChr = strrep(chr,'_ks_drivers_sorted.csv','')
I am trying to extract a substring from a text column using a regular expression, but in some cases, there are multiple instances of that substring in the string.
In those cases, I am finding that the query does not return the first occurrence of the substring. Does anyone know what I am doing wrong?
For example:
If I have this data:
create table data1
(full_text text, name text);
insert into data1 (full_text)
values ('I 56, donkey, moon, I 92')
I am using
UPDATE data1
SET name = substring(full_text from '%#"I ([0-9]{1,3})#"%' for '#')
and I want to get 'I 56' not 'I 92'
You can use regexp_matches() instead:
update data1
set full_text = (regexp_matches(full_text, 'I [0-9]{1,3}'))[1];
As no additional flag is passed, regexp_matches() only returns the first match - but it returns an array so you need to pick the first (and only) element from the result (that's the [1] part)
It is probably a good idea to limit the update to only rows that would match the regex in the first place:
update data1
set full_text = (regexp_matches(full_text, 'I [0-9]{1,3}'))[1]
where full_text ~ 'I [0-9]{1,3}'
Try the following expression. It will return the first occurrence:
SUBSTRING(full_text, 'I [0-9]{1,3}')
You can use regexp_match() In PostgreSQL 10+
select regexp_match('I 56, donkey, moon, I 92', 'I [0-9]{1,3}');
Quote from documentation:
In most cases regexp_matches() should be used with the g flag, since
if you only want the first match, it's easier and more efficient to
use regexp_match(). However, regexp_match() only exists in PostgreSQL
version 10 and up. When working in older versions, a common trick is
to place a regexp_matches() call in a sub-select...
I am new to Pig. In the script that I am writing I want to perform an operation similar to this:
foreach X GENERATE REPLACE(word,'.*abc.*','abc') OR REPLACE(word,'.*def.*','def').
If the first pattern matches then abc is replaced else if second pattern is matched then def is replaced. But I suppose the syntax is incorrect. Can someone help me with the syntax?
There are a few ways to do this, but since if the regex doesn't match the string, you'll just get your string back, this is pretty compact:
Y = FOREACH X GENERATE REPLACE(REPLACE(word, '.*abc.*', 'abc'), '.*def.*', 'def');
I'm comparing 2 URL query strings to see if they're equal; however, I want to ignore a specific query parameter (always with a numeric value) if it exists. So, these 2 query strings should be equal:
firstName=bobby&lastName=tables¶mToIgnore=2
firstName=bobby&lastName=tables¶mToIgnore=5
So, I tried to use a regex replace using the REReplaceNoCase function:
REReplaceNoCase(myQueryString, "¶mToIgnore=[0-9]*", "")
This works fine for the above example. I apply the replace to both strings and then compare. The problem is that I can't be sure that the param will be the last one in the string... the following 2 query strings should also be equal:
firstName=bobby&lastName=tables¶mToIgnore=2
paramToIgnore=5&firstName=bobby&lastName=tables
So, I changed the regex to make the preceding ampersand optional... "&?paramToIgnore=[0-9]*". But - these strings will still not be equal as I'll be left with an extra ampersand in one of the strings but not the other:
firstName=bobby&lastName=tables
&firstName=bobby&lastName=tables
Similarly, I can't just remove preceding and following ampersands ("&?paramToIgnore=[0-9]*&?") as if the query param is in the middle of the string I'll strip one ampersand too many in one string and not the other - e.g.
firstName=bobby&lastName=tables¶mToIgnore=2
firstName=bobby¶mToIgnore=5&lastName=tables
will become
firstName=bobby&lastName=tables
firstName=bobbylastName=tables
I can't seem to get my head around the logic of this... Can anyone help me out with a solution?
If you can't be sure of the order the parameters appear i would recommend, that you don't compare them by the string itsself.
I recommend splitting the string up like this:
String stringA = "firstName=bobby&lastName=tables¶mToIgnore=2";
String stringB = "firstName=bobby&lastName=tables¶mToIgnore=5";
String[] partsA = stringA.split("&");
String[] partsB = stringB.split("&");
Then go through arrays and make the paramToIgnore somehow euqal:
for(int i = 0; i < partsA.length; i++)
{
if(partsA[i].startsWith("paramToIgnore"){
partsA[i] = "IgnoreMePlease";
}
}
for(int j = 0; j < partsB.length; j++)
{
if(partsB[i].startsWith("paramToIgnore"){
partsB[i] = "IgnoreMePlease";
}
}
Then you can sort and compare the arrays to see if they are equal:
Arrays.sort(partsA);
Arrays.sort(partsB);
boolean b = Arrays.equals(partsA, partsB);
I'm pretty sure it's possible to make this more compact and give it a better performance. But with comparing strings like you do, you somehow alsways have to care about the order of your parameters.
You can use the QueryStringDeleteVar UDF on cflib to remove the query string variables you want to ignore from both strings, then compare them.
Make it in two steps:
first remove your param, as you described in example
then remove ampersand which is left at the begining or the end of query with separate regex, or any double/triple/... ampersands in the middle of the query
How about having an 'or' in the RegEx to match an ampersand at the start or the end?
¶mToIgnore=[0-9]*|paramToIgnore=[0-9]*&
Seems to do the job when testing in regexpal.com
try changing it to:
REReplaceNoCase(myQueryString, "&?paramToIgnore=[0-9]+", "")
plus instead of star should capture 1 or more of the preceding matched characters. It won't match anything but 0-9 so if there is another parameter after that it'll stop when it can't match any more digits.
Alternatively, you could use:
REReplaceNoCase(myQueryString, "&?paramToIgnore=[^&]", "")
This will match anything but an ampersand. It will cover the case if the parameter exists but there is no value; which is probably something you'd want to account for.