Combining string and numerical values

Hi, I'm doing a review sheet (not for a grade), and I'm hitting a snag with combining string and character vectors. Here's my problem:

Write a function my_password that will receive a string or character vector with a message and create a password that alternates between the final letter of each word and length of each word.

I've tried the following two functions, the first one only works if your in phrase is one word, and the second returns only a character vector:

function password=my_password(inphrase)
password= inphrase(end);
passnum= strlength(inphrase);
newpass= strcat(password, int2str(passnum))
end

function password = mypassword(inphrase);
rest = strtrim(char(inphrase));
password = '';
while ~isempty(rest)
  [word, rest] = strtok(rest);
  password = strcat(password,int2str(word));
end
end

[the cyclist]

I'm not certain I understand the rule for password creation. Is this right?

inphrase = 'I like MATLAB'

leads to

password = 'I1e4B6'

Also, can the password be returned as either string or character array, or does it need to be the same type as the input?

[AJ Schmidt]

The rule is supposed to take the last letter of every word and then the number of characters in every word, so the password for your string is correct. I'm not sure how to combine the use of both characters and string values to get the password. The password can be returned as a string or character array as far as I know, so long as the correct password is found.

[Stephen23]

>> str = 'I like MATLAB'
>> regexprep(str,'\s*(\w*)(\w)','$2${num2str(1+numel($1))}')
ans =
'I1e4B6'

Answer 1

[Ameer Hamza]

Try these two options

function newpass = my_password1(inphrase)
    words = strsplit(inphrase, ' ');
    last_char = cellfun(@(x) {x(end)}, words);
    lens = cellfun(@(x) {num2str(numel(x))}, words);
    X = cell(1,numel(words));
    X(1:2:end) = last_char(1:2:end);
    X(2:2:end) = lens(2:2:end);
    newpass = strjoin(X, '');
end

function newpass = my_password2(inphrase)
    words = strsplit(inphrase, ' ');
    last_char = cellfun(@(x) {x(end)}, words);
    lens = cellfun(@(x) {num2str(numel(x))}, words);
    newpass = strjoin(strcat(last_char, lens), '');
end

Test:

my_password1('A quick brown fox')
ans =
    'A5n3'
my_password2('A quick brown fox')
ans =
    'A1k5n5x3'

[AJ Schmidt]

Your second function finds the right answer, but we haven't learned the cellfun function yet, so I'm not sure I would be able to use that on a test or assignment, but thanks for finding a correct answer!

[Ameer Hamza]

cellfun is just a compact way to write a for loop. It applies the specified function to each element of the cell array.

[AJ Schmidt]

I have learned how to use for loops, so that could be a useful tool on my next exam. Would you mind putting for loops into your function instead of the cellfuns so I can compare the two?

[Ameer Hamza]

Let me give one example, you can convert others in a similar way.

last_char = cellfun(@(x) {x(end)}, words);

is equivalent to

last_char = cell(1, numel(words));
for i=1:numel(words)
    last_char{i} = words{i}(end);
end

[AJ Schmidt]

Awesome, thanks for your help!

[Ameer Hamza]

I am glad to be of help.