CODEWITHSUNDEEP
stringoctave
Andremoniy
Andremoniy

Reputation: 34900

Remove non-unique chars from string in MATLAB/octave

Let some variable is string abac, for example:

un =
{
  [1,1] = abac
}

I need to transform it to just abc, i.e. remove 3d symbol a. I have no ideas how to make it easy whithout great perversion with string octave functions. Any ideas?

Upvotes: 0

Views: 188

Answers (2)

carandraug
carandraug

Reputation: 13081

If you want the unique characters in the order they appear on the original string, the answer is still to unique but you need its second argument which returns the first (or last) index of each element.

octave> charv = "aaccbbahbc"
charv = aaccbbahbc
octave> [~, i] = unique (charv, "first")
i =

   1   5   3   8

octave> charv(sort (i))
ans = acbh

or in a single line:

octave> charv(sort (nthargout (2, @unique, charv, "first")))
ans = acbh

If you have many strings in a cell array, it gets a bit more complicated:

octave> charcv = {"aaccbbahbc", "erfyergfas"}
charcv = 
{
  [1,1] = aaccbbahbc
  [1,2] = erfyergfas
}
octave> [~, i] = cellfun (@unique, charcv , {"first"}, "UniformOutput", false)
i = 
{
  [1,1] =

     1   5   3   8

  [1,2] =

      9    1    3    7    2   10    4

}
octave> i = cellfun (@sort, i, "UniformOutput", false)
i = 
{
  [1,1] =

     1   3   5   8

  [1,2] =

      1    2    3    4    7    9   10

}
octave> cellfun (@subsref, charcv, num2cell (struct ("type", "()", "subs", num2cell (i))), "UniformOutput", false)
ans = 
{
  [1,1] = acbh
  [1,2] = erfygas
}

Upvotes: 1

beaker
beaker

Reputation: 16791

To find unique symbols in a single string within a cell array, use unique:

un =
{
  [1,1] = abac
  [1,2] = asdlfkjasdf
}

>> unique(un{1})
ans = abc
>> unique(un{2})
ans = adfjkls

To find the unique elements of all of the strings at once, use cellfun in conjunction with unique:

>> cellfun(@unique,un,'UniformOutput',false)
ans =
{
  [1,1] = abc
  [1,2] = adfjkls
}

Note that by default unique sorts the elements of the result, and unlike Matlab, Octave does not have a stable option to turn off this behavior.

Upvotes: 3

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