I am working with a messy manually maintained "database" that has a column containing a string with name,value pairs. I am trying to parse the entire column with regexp to pull out the values. The column is huge (>100,000 entries). As a proxy for my actual data, let's use this code:
line1={'''thing1'': ''-583'', ''thing2'': ''245'', ''thing3'': ''246'', ''morestuff'':, '''''};
line2={'''thing1'': ''617'', ''thing2'': ''239'', ''morestuff'':, '''''};
line3={'''thing1'': ''unexpected_string(with)parens5'', ''thing2'': 245, ''thing3'':''246'', ''morestuff'':, '''''};
mycell=vertcat(line1,line2,line3);
This captures the general issues encountered in the database. I want to extract what thing1, thing2, and thing3 are in each line using cellfun to output a scalar cell array. They should normally be 3 digit numbers, but sometimes they have an unexpected form. Sometimes thing3 is completely missing, without the name even showing up in the line. Sometimes there are minor formatting inconsistencies, like single quotes missing around the value, spaces missing, or dashes showing up in front of the three digit value. I have managed to handle all of these, except for the case where thing3 is completely missing.
My general approach has been to use expressions like this:
expr1='(?<=thing1''):\s?''?-?([\w\d().]*?)''?,';
expr2='(?<=thing2''):\s?''?-?([\w\d().]*?)''?,';
expr3='(?<=thing3''):\s?''?-?([\w\d().]*?)''?,';
This looks behind for thingX' and then tries to match : followed by zero or one spaces, followed by 0 or 1 single quote, followed by zero or one dash, followed by any combination of letters, numbers, parentheses, or periods (this is defined as the token), using a lazy match, until zero or one single quote is encountered, followed by a comma. I call regexp as regexp(___,'tokens','once') to return the matching token.
The problem is that when there is no match, regexp returns an empty array. This prevents me from using, say,
out=cellfun(#(x) regexp(x,expr3,'tokens','once'),mycell);
unless I call it with 'UniformOutput',false. The problem with that is twofold. First, I need to then manually find the rows where there was no match. For example, I can do this:
emptyout=cellfun(#(x) isempty(x),out);
emptyID=find(emptyout);
backfill=cell(length(emptyID),1);
[backfill{:}]=deal('Unknown');
out(emptyID)=backfill;
In this example, emptyID has a length of 1 so this code is overkill. But I believe this is the correct way to generalize for when it is longer. This code will change every empty cell array in out with the string Unknown. But this leads to the second problem. I've now got a 'messy' cell array of non-scalar values. I cannot, for example, check unique(out) as a result.
Pardon the long-windedness but I wanted to give a clear example of the problem. Now my actual question is in a few parts:
Is there a way to accomplish what I'm trying to do without using 'UniformOutput',false? For example, is there a way to have regexp pass a custom string if there is no match (e.g. pass 'Unknown' if there is no match)? I can think of one 'cheat', which would be to use the | operator in the expression, and if the first token is not matched, look for something that is ALWAYS found. I would then still need to double back through the output and change every instance of that result to 'Unknown'.
If I take the 'UniformOutput',false approach, how can I recover a scalar cell array at the end to easily manipulate it (e.g. pass it through unique)? I will admit I'm not 100% clear on scalar vs nonscalar cell arrays.
If there is some overall different approach that I'm not thinking of, I'm also open to it.
Tangential to the main question, I also tried using a single expression to run regexp using 3 tokens to pull out the values of thing1, thing2, and thing3 in one pass. This seems to require 'UniformOutput',false even when there are no empty results from regexp. I'm not sure how to get a scalar cell array using this approach (e.g. an Nx1 cell array where each cell is a 3x1 cell).
At the end of the day, I want to build a table using these results:
mytable=table(out1,out2,out3);
Edit: Using celldisp sheds some light on the problem:
celldisp(out)
out{1}{1} =
246
out{2} =
Unknown
out{3}{1} =
246
I assume that I need to change the structure of out so that the contents of out{1}{1} and out{3}{1} are instead just out{1} and out{3}. But I'm not sure how to accomplish this if I need 'UniformOutput',false.
Note: I've not used MATLAB and this doesn't answer the "efficient" aspect, but...
How about forcing there to always be a match?
Just thinking about you really wanting a match to skip this problem, how about an empty match?
Looking on the MATLAB help page here I can see a 'emptymatch' option, perhaps this is something to try.
E.g.
the_thing_i_want_to_find|
Match "the_thing_i_want_to_find" or an empty match, note the | character.
In capture group it might look like this:
(the_thing_i_want_to_find|)
As a workaround, I have found that using regexprep can be used to find entries where thing3 is missing. For example:
replace='$1 ''thing3'': ''Unknown'', ''morestuff''';
missingexpr='(?<=thing2'':\s?)(''?-?[\w\d().]*?''?,) ''morestuff''';
regexprep(mycell{2},missingexpr,replace)
ans =
''thing1': '617', 'thing2': '239', 'thing3': 'Unknown', 'morestuff':, '''
Applying it to the entire array:
fixedcell=cellfun(#(x) regexprep(x,missingexpr,replace),mycell);
out=cellfun(#(x) regexp(x,expr3,'tokens','once'),fixedcell,'UniformOutput',false);
This feels a little roundabout, but it works.
cellfun can be replaced with a plain old for loop. Your code will either be equally fast, or maybe even faster. cellfun is implemented with a loop anyway, there is no advantage of using it other than fewer lines of code. In your explicit loop, you can then check the output of regexp, and build your output array any way you like.
Suppose I have two files main.txt and sub.txt. Suppose both files have unique lines i.e. the same line of text does not occur twice in either file. Also suppose there are no empty lines in either file. Now, consider the files as sets of strings, with each member of the set occuring on a line. This is possible because of our uniqueness condition. Now suppose sub.txt is a subset of main.txt in this way. How do we compute the set difference of main.txt and sub.txt to produce a new file diff.txt? To be clear, the lines of diff.txt should be those that occur in main.txt but not sub.txt. There should be no empty lines in diff.txt. Order in diff.txt is irrelevant.
Example
main.txt:
Hello
World
How
You
Are
sub.txt:
World
Hello
diff.txt:
How
Are
You
Bonus Questions
How can I tell that one set is actually a subset of the other? This is an assumption in the question, but in practice we mightn't know this for sure and would want a way to check it automatically.
How can I tell if the lines in each file are truly unique?
How can I tell if there are no blank lines?
Bonus Answer
I'll answer the bonus questions first. Follow these steps in order to ensure the right conditions hold as stated in the question:
Open both files in Notepad++ and close any other files
Lexographically sort each file: https://superuser.com/questions/762279/sorting-lines-in-notepad-without-the-textfx-plugin
Ensure that the following regex has no matches in either file, which will guarantee they're duplicate-free: ^(.+$\r\n)\1. If you want to remove duplicates, replace all ocurrences of that regex with \1.
Ensure there are no blank lines in either file by searching for ^$. If any are found you can delete them manually.
Create a third file and paste the contents of both sub.txt and main.txt into this file. Then lexographically sort it. Count the number of occurrences of the regex: ^(.+$)\r\n\1 to detect duplicate lines. If the count matches the number of lines in sub.txt, then it's a subset of main.txt. Keep this file for later.
Main Answer
In the third file you created in the last part, search for ^(.+$)\r\n\1\r?\n? and replace with the empty string. This will remove all elements of sub.txt from main.txt leaving you with diff.txt.
Note: This approach may leave you with a single blank line at the end of diff.txt, in the case where there was a duplicate found there. In that case, just delete it manually.
I would like WinMerge to compare the full text but exclude a variable substring.
Orientation="West" PhysicalAddress="2395226" DefFieldFrmt="Uf4d0" UnitCustomText="sec"
Orientation="West" PhysicalAddress="2395230" DefFieldFrmt="Uf4d1" UnitCustomText="sec"
In the lines above I want to ignore the PhysicalAddress="xxx" and locate the changed DefFieldFrmt="Uf4d1"
I have tried adding the filter:
PhysicalAddress=".*"
However this filters the complete line.
The actual text before and after the PhysicalAddress="xxx" will vary so I need a filter that says: match prefix and match suffix but ignore target variable substring.
Help please.
According to the documentation, is not possible to use the line filters for this:
When a rule matches any part of the line, the entire difference is ignored. Therefore, you cannot filter just part of a line.
However, since WinMerge's source code is on GitHub, it is possible to add a feature request for this to its list of issues.
I have a text file in Notepad++ that contains about 66,000 words all in 1 line, and it is a set of 200 "lines" of output that are all unique and placed in 1 line in the basic JSON form {output:[{output1},{output2},...}]}.
There is a set of characters matching the RegEx expression "id":.........,"kind":"track" that occurs about 285 times in total, and I am trying to either single them out, or copy all of them at once.
Basically, without some super complicated RegEx terms, I am stuck because I can't figure out how to highlight all of them at once, and also the Remove Unbookmarked Lines feature does not apply because this is all in one line. I have only managed to be able to Mark every single occurrence.
So does this require a large number of steps to get the file into multiple lines and work from there, or is there something else I am missing?
Edit: I have come up with a set of Macro schemes that make the process of doing this manually work much faster. It's another alternative but still takes a few steps and quite some time.
Edit 2: I intended there to be an answer for actually just highlighting the different sections all at once, but I guess that it not possible. The answer here turns out to be more useful in my case, allowing me to have a list of IDs without everything else.
You seem to already have a regex which matches single instances of your pattern, so assuming it works and that we must use Notepad++ for this:
Replace .*?("id":.........,"kind":"track").*?(?="id".........,"kind":"track"|$) with \1.
If this textfile is valid JSON, this opens you up to other, non-notepad++ options, like using Python with the json module.
Edited to remove unnecessary steps
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.