I have a string and want to extract the numbers between the character 'w' and 's'. The positions of the the characters vary between different strings.
For example:
s = '1w12s01'
desired result: '12'
and
s = '102w22s21'
desired result: '22'
It can also be done using a regular expression with lookahead and lookbehind:
regexp(s,'(?<=w).*(?=s)','match')
The function strfind will do this easily enough. This will work as long as the number is always directly between a 'w' and and 's', both are only in the target string once, and the number you're after is the only thing between those two characters.
s = '102w22s21';
r = s((strfind(s, 'w')+1):(strfind(s, 's')-1));
Use this:
e = extractBetween(s,'w','s');
Related
What I mean is if I have a string, "apwswe", and another string "appegwisbnwe", if we "subtract" the two strings together, which means "appegwisbnwe" - "apwswe", I want to get "pegibn". Is there a way to do this? BTW pegibn is the characters that they don't have in "common" with eachother.
Not exactly a thing of beauty, but this will get you there:
subtrahend = "apwswe"
minuend = list("appegwisbnwe")
for char in subtrahend:
if minuend.count(char):
minuend.remove(char)
difference = "".join(minuend)
print(difference)
pgibne
Possible alternatives to rhurwitz's solution:
input = "appegwisbnwe"
for char, occurrences in collections.Counter("apwswe"):
input = input.replace(char, '', occurrences)
this is quite simple and can be implemented as a straightforward functools.reduce expression but will rewrite the input string as many times as there are different characters in the filter.
A possibly more efficient alternative as it works in O(len(input) + len(filter)) rather than O(len(input)*len(uniq(filter))
input = "appegwisbnwe"
filter = collections.Counter("apwswe")
output = ''
for c in input:
if filter[c]:
filter[c] -= 1
else:
output += c
Can some one explain what this line here does? This is part of an old matlab code I need to reuse for my work
matdir = [params.ariens '-' num2str(dirtimes(ii))];
I'm especially confused about the '-' part. Thanks a lot in advance.
Single quotes are used to create a string literal so '-' simply creates a string containing the hyphen character. In MATLAB, [ ... ] performs horizontal concatenation so the line that you have shown concatenates the string stored in params.ariens, the character '-' and the number dirtimes(ii) converted to a string using num2str to creat one long string made up of those three strings.
For example:
c = ['abc', '-', 'def']
% abc-def
class(c)
% char
d = ['abc', '-', num2str(10)]
% abc-10
I have an cell-array of dimensions 1x6 like this:
A = {'25_2.mat','25_3.mat','25_4.mat','25_5.mat','25_6.mat','25_7.mat'};
I want to read for example from the A{1} , the number after the '_' i.e 2 for my example
Using cellfun, strfind and str2double
out = cellfun(#(x) str2double(x(strfind(x,'_')+1:strfind(x,'.')-1)),A)
How does it work?
This code simply finds the index of character one number after the occurrence of '_'. Lets call it as start_index. Then finds the character one number lesser than the index of occurrence of '.' character. Lets call it as end_index. Then retrieves all the characters between start_index and end_index. Finally converts those characters to numbers using str2double.
Sample Input:
A = {'2545_23.mat','2_3.mat','250_4.mat','25_51.mat','25_6.mat','25_7.mat'};
Output:
>> out
out =
23 3 4 51 6 7
You can access the contents of the cell by using the curly braces{...}. Once you have access to the contents, you can use indexes to access the elements of the string as you would do with a normal array. For example:
test = {'25_2.mat', '25_3.mat', '25_4.mat', '25_5.mat', '25_6.mat', '25_7.mat'}
character = test{1}(4);
If your string length is variable, you can use strfind to find the index of the character you want.
Assuming the numbers are non-negative integers after the _ sign: use a regular expression with lookbehind, and then convert from string to number:
numbers = cellfun(#(x) str2num(x{1}), regexp(A, '(?<=\_)\d+', 'match'));
I have a string and I need two characters to be returned.
I tried with strsplit but the delimiter must be a string and I don't have any delimiters in my string. Instead, I always want to get the second number in my string. The number is always 2 digits.
Example: 001a02.jpg I use the fileparts function to delete the extension of the image (jpg), so I get this string: 001a02
The expected return value is 02
Another example: 001A43a . Return values: 43
Another one: 002A12. Return values: 12
All the filenames are in a matrix 1002x1. Maybe I can use textscan but in the second example, it gives "43a" as a result.
(Just so this question doesn't remain unanswered, here's a possible approach: )
One way to go about this uses splitting with regular expressions (MATLAB's strsplit which you mentioned):
str = '001a02.jpg';
C = strsplit(str,'[a-zA-Z.]','DelimiterType','RegularExpression');
Results in:
C =
'001' '02' ''
In older versions of MATLAB, before strsplit was introduced, similar functionality was achieved using regexp(...,'split').
If you want to learn more about regular expressions (abbreviated as "regex" or "regexp"), there are many online resources (JGI..)
In your case, if you only need to take the 5th and 6th characters from the string you could use:
D = str(5:6);
... and if you want to convert those into numbers you could use:
E = str2double(str(5:6));
If your number is always at a certain position in the string, you can simply index this position.
In the examples you gave, the number is always the 5th and 6th characters in the string.
filename = '002A12';
num = str2num(filename(5:6));
Otherwise, if the formating is more complex, you may want to use a regular expression. There is a similar question matlab - extracting numbers from (odd) string. Modifying the code found there you can do the following
all_num = regexp(filename, '\d+', 'match'); %Find all numbers in the filename
num = str2num(all_num{2}) %Convert second number from str
This may be a very simple task for many but I could not find anything appropriate for me.
I have a file name: filenm_A006.2011.269.10.47.G25_2010
I want to separate all its parts (separated by . and _) to use them separately. How can I do it with simple matlab commands?
Kind Regards,
Mushi
I recommend regexp:
fname = 'filenm_A006.2011.269.10.47.G25_2010';
parts = regexp(fname, '[^_.]+', 'match');
parts =
'filenm' 'A006' '2011' '269' '10' '47' 'G25' '2010'
You can now refer to parts{1} through parts{8} for the pieces. Explanation: the regexp pattern [^_.] means all characters not equal to _ or ., and the + means you want groups of at least 1 character. Then 'match' asks the regexp function to return a cell array of the strings of all the matches of that pattern. There are other regexp modes; for example, the indices of each piece of the file.
Use the command
strsplit.
cellArrayOfParts = strsplit(fileName,{'.' '_'});
You can use strsplit to split it:
strsplit('filenm_A006.2011.269.10.47.G25_2010',{'_','.'})
ans =
'filenm' 'A006' '2011' '269' '10' '47' 'G25' '2010'
Another option is to use regexp, like Peter suggested.