I have to handle a weird CSV format, and I have been running into problems. The string I have been able to work out thus far is
(?:\s*(?:\"([^\"]*)\"|([^,]+))\s*?)+?
My files are often broken and irregular, since we have to deal with OCR'd text which is usually not checked by our users. Therefore, we tend to end up with lots of weird things, like a single " within a field, or even a newline character(which is why I am using Regex instead of my previous readLine()-based solution). I've gotten it to parse most everything correctly, except it captures [,] [,]. How can I get it to NOT select fields with only a single comma? When I try and have it not select commas, it turns "156,000" into [156] and [000]
The test string I've been using is
"156,000","",""i","parts","dog"","","Monthly "running" totals"
The ideal desire capture output is
[156,000],[],[i],[parts],[dog],[],[Monthly "running" totals]
I can do with or without the internal quotes, since I can always just strip them during processing.
Thank you all very much for your time.
Your CSV is indeed irregular and difficult to parse. I suggest you do 2 replacements first to your data.
// remove all invalid double ""
input = Regex.Replace(input, #"(?<!,|^)""(?=,|$)|(?<=,)""(?!,|$)", "\"");
// now escape all inner "
input = Regex.Replace(input, #"(?<!,|^)"(?!,|$)", #"\\\"");
// at this stage your have proper CSV data and I suggest using a good .NET csv parser
// to parse your data and get individual values
Replacement 1 demo
Replacement 2 demo
Related
I'm cleaning up some ancient HTML help files and there are a lot of double-spaces that I'd like to clean up (replace each double-space with single).
Sample: <li><b>% Successful</b>. The percentage of jobs that returned a confirmation.</li>
I want to find double-spaces only before the start of sentences or between words (so between the setting label or between 'percentage' and 'of', not spaces in isolation or before the XML tags).
I tried a simple search for two spaces, but that also brings up the tab/space mixture that the creator used for formatting the indents, so I'm getting five useless results for every relevant one.
Is there a single regex that would help with both use cases, or is it better to use two different ones for each format? I'm fine either way, just am still pretty new to regexes and not sure where to start on this one.
Spaces between periods and text (three here for a better visual):
<li><b>Submit Time</b>. The time the job was scheduled.</li>
Spaces between words (three here as well):
<li><b>End Time</b>. The date/time when the job was completed or canceled.</li>
I'm looking for multiple spaces either between words or at the start of sentences (generally after the setting name period).
I have a string that represents multiple DNs for Active Directory but has been separated by commas instead of ;
The String:
CN=Admins,ou=App1,ou=groups,dc=pkldap,dc=internal,
CN=Auditors,ou=App1,ou=groups,dc=pkldap,dc=internal,
CN=Operators,ou=App2,ou=groups,dc=pkldap,dc=internal
I am trying to write a regex that will match on both ou=App1 and not the ou=App2 but then also make the , after dc=internal become a ;
Is this possible?
The result would be:
CN=Admins,ou=App1,ou=groups,dc=pkldap,dc=internal;
CN=Auditors,ou=App1,ou=groups,dc=pkldap,dc=internal;
Using #strip and #sub to Clean Up Your LDIF Data
Really, the "correct" answer would be to get valid LDIF in the first place, and then parse it as such with a gem like Net::LDAP. However, the changes you want to your existing file are fairly trivial. For example, we'll start by assigning the String data from your question to a variable named ldif using a here-document literal:
ldif = <<~'LDIF'
CN=Admins,ou=App1,ou=groups,dc=pkldap,dc=internal,
CN=Auditors,ou=App1,ou=groups,dc=pkldap,dc=internal,
CN=Operators,ou=App2,ou=groups,dc=pkldap,dc=internal
LDIF
You can now modify and match the lines from the String that you want with String#each_line to iterate, and String#gsub and a Regexp lookahead assertion to find and collect the lines you want using Array#select on the output from #each_line, and storing the results into a matching_apps Array.
This all sounds much more complicated than it is. Consider the following method chain, which is really just a one-liner wrapped for readability:
matching_apps =
ldif.each_line.select { _1.match? /ou=App1(?=[,;]?$?)/ }
.map { _1.strip.sub /[,;]$/, ";" }
#=>
["CN=Admins,ou=App1,ou=groups,dc=pkldap,dc=internal;",
"CN=Auditors,ou=App1,ou=groups,dc=pkldap,dc=internal;"]
The use of String#strip and String#sub will help to ensure that all lines are normalized the way you want, including the trailing semicolons. However, this is likely to cause problems in subsequent steps, so I'd probably recommend removing those trailing semicolons as well.
Note: You can stop reading here if you just want to solve your immediate question as originally posted. The rest of the answer covers additional considerations related to data normalization, and provides some examples on how and why you might want to strip the semicolons as well.
Why and How to Normalize without Semicolons
You can replace the final substitution from #sub with an empty String (e.g. "") to remove the trailing semicolons (if present). Normalizing without the semicolons now may save you the trouble of having to clean up those lines again later when you iterate over the Array of results stored in matching_apps from Array#select.
For example, if you need to rejoin lines with commas, interpolate the lines within other String objects in subsequent steps, or do anything where those stored semicolons may be an unexpected surprise it's better to deal with it sooner rather than later. If you really need the trailing semicolons, it's very easy to use String#concat or other forms of String interpolation to add them back, but having unexpected characters in a String can be a source of unexpected bugs that are best avoided unless you're sure you'll always need that semicolon at the end.
Example 1: Output Where Semicolons Might be Unexpected
For example, suppose you want to use the results to format output for a command-line client where a trailing semicolon wouldn't be expected. The following works nicely because the semicolons are already stripped:
matching_apps =
ldif.each_line.select { _1.match? /ou=App1(?=[,;]?$?)/ }
.map { _1.strip.sub /[,;]$/, "" }
printf "Make the following calls:\n\n"
matching_apps.each_with_index do |dn, idx|
puts %(#{idx.succ}. ldapsearch -D '#{dn}' [opts])
end
This would print out:
Make the following calls:
1. ldapsearch -D 'CN=Admins,ou=App1,ou=groups,dc=pkldap,dc=internal' [opts]
2. ldapsearch -D 'CN=Auditors,ou=App1,ou=groups,dc=pkldap,dc=internal' [opts]
without having to first strip any trailing semicolons that might not work with the printed command, tool, or other output.
Examples of Rejoining with Commas and Semicolons
On the other hand, you can just as easily rejoin the Array elements with a comma or semicolon if you want. Consider the following two examples:
matching_apps.join ", "
#=> "CN=Admins,ou=App1,ou=groups,dc=pkldap,dc=internal, CN=Auditors,ou=App1,ou=groups,dc=pkldap,dc=internal"
p format("(%s)", matching_apps.join("; "))
#=> "(CN=Admins,ou=App1,ou=groups,dc=pkldap,dc=internal; CN=Auditors,ou=App1,ou=groups,dc=pkldap,dc=internal)"
Keep Flexibility in Mind
If the String objects in your Array still had the trailing semicolons, you'd have to do something about them. So, unless you already know what you plan to do with each String, and whether or not the semicolons will be needed, it's probably best to keep them out of matching_apps in the first place to optimize for flexibility. That's just an opinion, to be sure, but definitely one worth considering.
My problem is that I have a document that is split into sections, each section is noted by a single line header - [Header1], [Header2], etc. - and contains various types of data sets separated into individual lines, where each line is begun by a label indicating what type of data follows, like this:
[Header1]
data_label_type1 = 1,2,3
data_label_type2 = 1,2,3,4
data_label_type1 = 1,2,3,4,5
data_label_type3 = 1,2
Note the headers/sections are out of order, so Header1 doesn't always start a document and Header2 won't always follow.
A bit off topic, but the data sets are results from an experiment I'm mainting for a thesis.
I want to be able to capture type 1 data found only in the first section (under Header1) using a single regex function. After capturing it I was going to use replace and another function to convert the captured data to a different form.
Initially I was using the regex type1\h*=\h*([[:graph:]]*) but this only goes line by line, and I've got hundreds of documents - potentially tens of thousands of individal lines to catch.
I can use regex to convert my data well enough, but my problem lies in that I have no idea how capture type 1 data from Header1 exclusively. Any help, tips or pointers to start some experimenting would be really appreciated!
Regex apparently not capable of providing a solution, will use alternatives such as a parser instead.
I have no experience with regular expressions and would love some help and suggestions on a possible solution to deleting parts of file names contained in a csv file.
Problem:
A list of exported file names contains a random unique identifier that I need isolated. The unique identifier has no predictable pattern, however the aspects which need removing do. Each file name ends with one of the following variations:
V, -V, or %20V followed by a random number sequence with possible spaces, additional "-","" and ending with .PDF
examples:
GTD-LVOE-43-0021 V10 0.PDF
GTD-LVOE-43-0021-V34-2.PDF
GTD-LVOE-43-0021_V02_9.PDF
GTD-LVOE-43-0021 V49.9.PDF
Solution:
My plan was to write a script to select of the first occurrence of a V from the end of the string and then delete it and everything to the right of it. Then the file names can be cleaned up by deleting any "-" or "_" and white space that occurs at the end of a string.
Question:
How can I do this with a regular expression and is my line of thinking even close to the right approach to solving this?
REGEX: [\s\-_]V.*?\.PDF
Might do the trick. You'd still need to replace away any leading - and _, but it should get you down the path, hopefully.
This would read as follows..
start with a whitespace, - OR _ followed by a V. Then take everything until you get to the first .PDF
I recently discussed editors with a co-worker. He uses one of the less popular editors and I use another (I won't say which ones since it's not relevant and I want to avoid an editor flame war). I was saying that I didn't like his editor as much because it doesn't let you do find/replace with regular expressions.
He said he's never wanted to do that, which was surprising since it's something I find myself doing all the time. However, off the top of my head I wasn't able to come up with more than one or two examples. Can anyone here offer some examples of times when they've found regex find/replace useful in their editor? Here's what I've been able to come up with since then as examples of things that I've actually had to do:
Strip the beginning of a line off of every line in a file that looks like:
Line 25634 :
Line 632157 :
Taking a few dozen files with a standard header which is slightly different for each file and stripping the first 19 lines from all of them all at once.
Piping the result of a MySQL select statement into a text file, then removing all of the formatting junk and reformatting it as a Python dictionary for use in a simple script.
In a CSV file with no escaped commas, replace the first character of the 8th column of each row with a capital A.
Given a bunch of GDB stack traces with lines like
#3 0x080a6d61 in _mvl_set_req_done (req=0x82624a4, result=27158) at ../../mvl/src/mvl_serv.c:850
strip out everything from each line except the function names.
Does anyone else have any real-life examples? The next time this comes up, I'd like to be more prepared to list good examples of why this feature is useful.
Just last week, I used regex find/replace to convert a CSV file to an XML file.
Simple enough to do really, just chop up each field (luckily it didn't have any escaped commas) and push it back out with the appropriate tags in place of the commas.
Regex make it easy to replace whole words using word boundaries.
(\b\w+\b)
So you can replace unwanted words in your file without disturbing words like Scunthorpe
Yesterday I took a create table statement I made for an Oracle table and converted the fields to setString() method calls using JDBC and PreparedStatements. The table's field names were mapped to my class properties, so regex search and replace was the perfect fit.
Create Table text:
...
field_1 VARCHAR2(100) NULL,
field_2 VARCHAR2(10) NULL,
field_3 NUMBER(8) NULL,
field_4 VARCHAR2(100) NULL,
....
My Regex Search:
/([a-z_])+ .*?,?/
My Replacement:
pstmt.setString(1, \1);
The result:
...
pstmt.setString(1, field_1);
pstmt.setString(1, field_2);
pstmt.setString(1, field_3);
pstmt.setString(1, field_4);
....
I then went through and manually set the position int for each call and changed the method to setInt() (and others) where necessary, but that worked handy for me. I actually used it three or four times for similar field to method call conversions.
I like to use regexps to reformat lists of items like this:
int item1
double item2
to
public void item1(int item1){
}
public void item2(double item2){
}
This can be a big time saver.
I use it all the time when someone sends me a list of patient visit numbers in a column (say 100-200) and I need them in a '0000000444','000000004445' format. works wonders for me!
I also use it to pull out email addresses in an email. I send out group emails often and all the bounced returns come back in one email. So, I regex to pull them all out and then drop them into a string var to remove from the database.
I even wrote a little dialog prog to apply regex to my clipboard. It grabs the contents applies the regex and then loads it back into the clipboard.
One thing I use it for in web development all the time is stripping some text of its HTML tags. This might need to be done to sanitize user input for security, or for displaying a preview of a news article. For example, if you have an article with lots of HTML tags for formatting, you can't just do LEFT(article_text,100) + '...' (plus a "read more" link) and render that on a page at the risk of breaking the page by splitting apart an HTML tag.
Also, I've had to strip img tags in database records that link to images that no longer exist. And let's not forget web form validation. If you want to make a user has entered a correct email address (syntactically speaking) into a web form this is about the only way of checking it thoroughly.
I've just pasted a long character sequence into a string literal, and now I want to break it up into a concatenation of shorter string literals so it doesn't wrap. I also want it to be readable, so I want to break only after spaces. I select the whole string (minus the quotation marks) and do an in-selection-only replace-all with this regex:
/.{20,60} /
...and this replacement:
/$0"ΒΆ + "/
...where the pilcrow is an actual newline, and the number of spaces varies from one incident to the next. Result:
String s = "I recently discussed editors with a co-worker. He uses one "
+ "of the less popular editors and I use another (I won't say "
+ "which ones since it's not relevant and I want to avoid an "
+ "editor flame war). I was saying that I didn't like his "
+ "editor as much because it doesn't let you do find/replace "
+ "with regular expressions.";
The first thing I do with any editor is try to figure out it's Regex oddities. I use it all the time. Nothing really crazy, but it's handy when you've got to copy/paste stuff between different types of text - SQL <-> PHP is the one I do most often - and you don't want to fart around making the same change 500 times.
Regex is very handy any time I am trying to replace a value that spans multiple lines. Or when I want to replace a value with something that contains a line break.
I also like that you can match things in a regular expression and not replace the full match using the $# syntax to output the portion of the match you want to maintain.
I agree with you on points 3, 4, and 5 but not necessarily points 1 and 2.
In some cases 1 and 2 are easier to achieve using a anonymous keyboard macro.
By this I mean doing the following:
Position the cursor on the first line
Start a keyboard macro recording
Modify the first line
Position the cursor on the next line
Stop record.
Now all that is needed to modify the next line is to repeat the macro.
I could live with out support for regex but could not live without anonymous keyboard macros.