How do i find one string with another?
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Hi Guys,
I am trying to sequentially look for a string in a document and was wondering how I would go about doing that.
Essentially I have a large file called A.csv with a bunch of columns [date], [Open], [Low], [Close], [Volume], [Adj.Close], [Ret]
I want to write a script that will find a date 4/5/2000 and will pull the corresponding return for that date.
This is the trick: the day is a variable. All of the dates have a different month and year so it looks something like 1/3/2000, 2/4/2000, 3/1/2000. How do I find a match using the year and month. For example, I want to pull 1/*/2006, 7/*/2007, but I don't know what the * is (it could be 1, 2, 3, 4, 5, etc...)
The first row for example (skipping the header), looks like: 1/3/2000,78.75,78.94,58.13,66.19,1642300,62.37,0.569183903
Thank you for all of your help guys!
-Larry G.
采纳的回答
Andrew Newell
2012-1-11
The trick is to use regular expressions. The first line below searches for any string that has one or more integers between '1/' and '/2000'. One line at a time is examined and the number extracted if there is a match.
match_str = '1/[0-9]+/2000';
match_vector = zeros(32000,1); % Use whatever size you're sure is large enough
fid=fopen('yourfile.m');
count=0;
tline = fgetl(fid);
while ischar(tline)
if regexp(tline,match_str)
A = textscan(tline,'%*s %*f %*f %*f %*f %*d %*f %f','delimiter',',');
count = count+1;
match_vector(count) = A{1};
end
end
fclose(fid);
5 个评论
Andrew Newell
2012-1-11
Ah - I found the error: I should be updating match_vector inside the IF-END block.
更多回答(2 个)
Walter Roberson
2012-1-11
regexp(STRING, '^(?<=1/\d+/2006/.*,)[^,]+$', 'match', 'dotexceptnewline', 'lineanchors')
0 个评论
Laurentiu Galan
2012-1-11
1 个评论
Andrew Newell
2012-1-11
I don't see anything obvious. For any code I suggest the following sequence: (1) test it thoroughly to make sure it works; (2) run it with the MATLAB Profiler and see where the code is spending most of its time; and (3) look for ways to speed up that part of the code.
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