Suppose I have a string 'johndoe#hotmail.com'. I want to store the string before and after "#" into 2 separate strings. What would be the easiest method of finding the "#" character or other characters in the string?
STRTOK and an index operation should do the trick:
str = 'johndoe#hotmail.com';
[name,address] = strtok(str,'#');
address = address(2:end);
Or the last line could also be:
address(1) = '';
You can use strread:
str = 'johndoe#hotmail.com';
[a b] = strread(str, '%s %s', 'delimiter','#')
a =
'johndoe'
b =
'hotmail.com'
For "easiest",
>> email = 'johndoe#hotmail.com'
email =
johndoe#hotmail.com
>> email == '#'
ans =
Columns 1 through 13
0 0 0 0 0 0 0 1 0 0 0 0 0
Columns 14 through 19
0 0 0 0 0 0
>> at = find(email == '#')
at =
8
>> email(1:at-1)
ans =
johndoe
>> email(at+1:end)
ans =
hotmail.com
It would be slightly more complicated if you were looking for something with more than one character, or you weren't sure if there was exactly one #, and in that case MATLAB has a lot of functions for searching through text, including regular expressions (see doc regexp).
TEXTSCAN works too.
str = 'johndoe#hotmail.com';
parts = textscan(str, '%s %s', 'Delimiter', '#');
returns a cell array where parts{1} is 'johndoe' and parts{2} is 'hotmail.com'.
If this thread isn't completely enumerated by now, may I add another? A handy perl-based MATLAB function:
email = 'johndoe#hotmail.com';
parts = regexp(email,'#', 'split');
parts is a two element cell array similar to mtrw's implementation of textscan. Maybe overkill, but regexp is much more useful when splitting a string by multiple delimiting characters or pattern searching. The only downside is the use of regular expressions which I still haven't mastered after 15 years of coding.
I used strtok and strrep from Matlab instead.
String email = "johndoe#hotmail.com";
String a[] = email.split("#");
String def = null;
String ghi = null;
for(int i=0;i<a.length;i++){
def = a[0];
ghi = a[1];
}
Related
A = {'a','b','c','b','a',...}
A is a <1X400> cell array and I want to create a matrix from A such that if the cell is a, the matrix shows 1, if it is b, it shows as 2 in the matrix and 3 for c.
Thank you.
Specific Case
For a simple specific case as listed in the question, you can use char to convert all the cell elements to characters and then subtract 96 from it, which is ascii equivalent of 'a'-1 -
A_numeric = char(A)-96
Sample run -
>> A
A =
'a' 'b' 'c' 'b' 'a'
>> A_numeric = char(A)-96
A_numeric =
1
2
3
2
1
Generic Case
For a generic substitution case, you need to do a bit more of work like so -
%// Inputs
A = {'correct','boss','cat','boss','correct','cat'}
newcellval = {'correct','cat','boss'}
newnumval = [8,2,5]
[unqcell,~,idx] = unique(A,'stable')
[~,newcell_idx,unqcell_idx] = intersect(newcellval,unqcell,'stable')
A_numeric = newnumval(changem(idx,newcell_idx,unqcell_idx))
Sample input-output -
>> A,newcellval,newnumval
A =
'correct' 'boss' 'cat' 'boss' 'correct' 'cat'
newcellval =
'correct' 'cat' 'boss'
newnumval =
8 2 5
>> A_numeric
A_numeric =
8 5 2 5 8 2
That's easy:
result = cell2mat(A)-'a'+1
For a generic association of letters to numbers 1,2,3...:
letters2numbers = 'abc'; %// 'a'->1, 'b'->2 etc.
[~, result] = ismember(cell2mat(A), letters2numbers)
For a generic association of strings to numbers 1,2,3...:
strings2numbers = {'hi', 'hello', 'hey', 'good morning', 'howdy'};
A = {'hello', 'hi', 'hello', 'howdy', 'bye'};
[~, result] = ismember(A, strings2numbers)
In this example,
result =
2 1 2 5 0
use a For Loop which iterate over A and convert character to number
for loop = 1:length(A)
outMat(loop) = char(A(loop)) - 96
end
I hope it works.
How do I get the result when '#' exist in the string will return 1 else 0. Now, I get the results of 0 0, although second string contain the character of '#'.
A = {'#'};
B = {'http://www.mathworks.com/help/matlab/ref/strcmpi.html',
'http://www.mathworks.com/help/matlab/ref/strcmpi#dfvfv.html'};
match = strcmpi(A,B)
Output:
match =
0
0
Desire Output
match =
0
1
Edit2:
why do i use the same concept as above but i get the wrong results? I want to check whether the file that store in 'data14' got 'javascript' & 'disableclick' at the same time. But the results return me all '1'.
for i = 1:4
A14 = {'javascript'};
B14 = {'disableclick'};
data14 = importdata(strcat('f14data/f14_data', int2str(i)));
feature14_data=any(cellfun(#(n) isempty(n), strfind(data14, A14{1}))) & any(cellfun(#(n) isempty(n), strfind(data14, B14{1})))
feature14(i)=feature14_data
end
This can be used to get desired output:
cellfun(#(n) ~isempty(n), strfind(B, A{1}))
You could use ismember iteratively:
cellfun(#(x)ismember('#',x), B)
How would I be able to do the equivalent of this with strings:
a = [1 2 3; 4 5 6];
c = [];
for i=1:5
b = a(1,:)+i;
c = [c;b];
end
c =
2 3 4
3 4 5
4 5 6
5 6 7
6 7 8
Basically looking to combine several strings into a Matrix.
You're growing a variable in a loop, which is a kind of sin in Matlab :) So I'm going to show you some better ways of doing array concatenation.
There's cell strings:
>> C = {
'In a cell string, it'
'doesn''t matter'
'if the strings'
'are not of equal lenght'};
>> C{2}
ans =
doesn't matter
Which you could use in a loop like so:
% NOTE: always pre-allocate everything before a loop
C = cell(5,1);
for ii = 1:5
% assign some random characters
C{ii} = char( '0'+round(rand(1+round(rand*10),1)*('z'-'0')) );
end
There's ordinary arrays, which have as a drawback that you have to know the size of all your strings beforehand:
a = [...
'testy' % works
'droop'
];
b = [...
'testing' % ERROR: CAT arguments dimensions
'if this works too' % are not consistent.
];
for these cases, use char:
>> b = char(...
'testing',...
'if this works too'...
);
b =
'testing '
'if this works too'
Note how char pads the first string with spaces to fit the length of the second string. Now again: don't use this in a loop, unless you've pre-allocated the array, or if there really is no other way to go.
Type help strfun on the Matlab command prompt to get an overview of all string-related functions available in Matlab.
You mean storing a string on each matrix position? You can't do that, since matrices are defined over basic types. You can have a CHAR on each position:
>> a = 'bla';
>> b = [a; a]
b <2x3 char> =
bla
bla
>> b(2,3) = 'e'
b =
bla
ble
If you want to store matrices, use a cell array (MATLAB reference, Blog of Loren Shure), which are kind of similar but using "{}" instead of "()":
>> c = {a; a}
c =
'bla'
'bla'
>> c{2}
ans =
bla
I have a string stored in sqlite database and I've assigned it to a var, e.g. string
string = "First line and string. This should be another string in a new line"
I want to split this string into two separated strings, the dot (.) must be replace with (\n) new line char
At the moment I'm stuck and any help would be great!!
for row in db:nrows("SELECT * FROM contents WHERE section='accounts'") do
tabledata[int] = string.gsub(row.contentName, "%.", "\n")
int = int+1
end
I tried the other questions posted here in stachoverflow but with zero luck
What about this solution:`
s = "First line and string. This should be another string in a new line"
a,b=s:match"([^.]*).(.*)"
print(a)
print(b)
Are you looking to actually split the string into two different string objects? If so maybe this can help. It's a function I wrote to add some additional functionality to the standard string library. You can use it as-is or rename it to what ever you like.
--[[
string.split (s, p)
====================================================================
Splits the string [s] into substrings wherever pattern [p] occurs.
Returns: a table of substrings or, if no match is made [nil].
--]]
string.split = function(s, p)
local temp = {}
local index = 0
local last_index = string.len(s)
while true do
local i, e = string.find(s, p, index)
if i and e then
local next_index = e + 1
local word_bound = i - 1
table.insert(temp, string.sub(s, index, word_bound))
index = next_index
else
if index > 0 and index <= last_index then
table.insert(temp, string.sub(s, index, last_index))
elseif index == 0 then
temp = nil
end
break
end
end
return temp
end
Using it is very simple, it returns a tables of strings.
Lua 5.1.4 Copyright (C) 1994-2008 Lua.org, PUC-Rio
> s = "First line and string. This should be another string in a new line"
> t = string.split(s, "%.")
> print(table.concat(t, "\n"))
First line and string
This should be another string in a new line
> print(table.maxn(t))
2
I've a string like this "FBECGHD" and i need to use MATLAB and generate all the required possible permutations? In there a specific MATLAB function that does this task or should I define a custom MATLAB function that perform this task?
Use the perms function. A string in matlab is a list of characters, so it will permute them:
A = 'FBECGHD';
perms(A)
You can also store the output (e.g. P = perms(A)), and, if A is an N-character string, P is a N!-by-N array, where each row corresponds to a permutation.
If you are interested in unique permutations, you can use:
unique(perms(A), 'rows')
to remove duplicates (otherwise something like 'ABB' would give 6 results, instead of the 3 that you might expect).
As Richante answered, P = perms(A) is very handy for this. You may also notice that P is of type char and it's not convenient to subset/select individual permutation. Below worked for me:
str = 'FBECGHD';
A = perms(str);
B = cellstr(reshape(A,7,[])');
C = unique(B);
It also appears that unique(A, 'rows') is not removing duplicate values:
>> A=[11, 11];
>> unique(A, 'rows')
ans =
11 11
However, unique(A) would:
>> unique(A)
ans =
11
I am not a matlab pro by any means and I didn't investigate this exhaustively but at least in some cases it appears that reshape is not what you want. Notice that below gives 999 and 191 as permutations of 199 which isn't true. The reshape function as written appears to operate "column-wise" on A:
>> str = '199';
A = perms(str);
B = cellstr(reshape(A,3,[])');
C = unique(B);
>> C
C =
'191'
'199'
'911'
'919'
'999'
Below does not produce 999 or 191:
B = {};
index = 1;
while true
try
substring = A(index,:);
B{index}=substring;
index = index + 1;
catch
break
end
end
C = unique(B)
C =
'199' '919' '991'