how to store value in variables of one column in cell array from another column in cell array?

The problem is something like this:

V_table =

8×4 table

Variable lb initial_val ub

_____________ ____ ___________ ____

{'Lser_B7Tx'} 0 0.4 2

{'Lser_B7Rx'} 0 0.4 2

{'QCsmd' } 30 70 80

{'QLemb' } 30 60 80

{'Lshu_B7' } 0 4 10

{'fQ' } 2000 2500 3000

{'Cshu_B7' } 0 0.01 2

{'QLsmd' } 30 60 80

This is code I am using for what I try to achieve i.e. to store the values such as 0.4,0.4,....(initial_value) to variables Lser_B7Tx', 'Lser_B7Rx'......'QLsmd'.

for i = 1:length((V_table.Variable)

V_table.Variable{i} = V_table.initial_val{i}

V_table.Variable

end

But I am getting the error : Error using nport_B7DPX (line 125)

Brace indexing is not supported for variables of this type.

Would anyone please let me know how can I assign value to the variables of cell array

[Pooja Kumari]

Can you share the table file.

Answer 1

[Voss]

% your V_table:
V_table = table( ...
    {'Lser_B7Tx';'Lser_B7Rx';'QCsmd';'QLemb';'Lshu_B7';'fQ';'Cshu_B7';'QLsmd'}, ...
    [0;0;30;30;0;2000;0;30], ...
    [0.4;0.4;70;60;4;2500;0.01;60], ...
    [2;2;80;80;10;3000;2;80], ...
    'VariableNames',{'Variable','lb','initial_val','ub'})

V_table = 8×4 table
      Variable        lb     initial_val     ub 
    _____________    ____    ___________    ____

    {'Lser_B7Tx'}       0        0.4           2
    {'Lser_B7Rx'}       0        0.4           2
    {'QCsmd'    }      30         70          80
    {'QLemb'    }      30         60          80
    {'Lshu_B7'  }       0          4          10
    {'fQ'       }    2000       2500        3000
    {'Cshu_B7'  }       0       0.01           2
    {'QLsmd'    }      30         60          80

Instead of making a bunch of different variables in your workspace that contain all the same information of what's already in the table, you can redefine your table slightly, so that the Variable column is the RowNames of the table:

V_table.Properties.RowNames = V_table.Variable;
V_table.Variable = []

V_table = 8×3 table
                  lb     initial_val     ub 
                 ____    ___________    ____

    Lser_B7Tx       0        0.4           2
    Lser_B7Rx       0        0.4           2
    QCsmd          30         70          80
    QLemb          30         60          80
    Lshu_B7         0          4          10
    fQ           2000       2500        3000
    Cshu_B7         0       0.01           2
    QLsmd          30         60          80

Then you can get easily whatever you need, by indexing with a row name and a column name:

V_table{'fQ','lb'}

ans = 2000

V_table{'QLsmd','initial_val'}

ans = 60

V_table{'QCsmd','ub'}

ans = 80

[Aakriti Srivastava]

Hy Voss, Thanks for this way of organising the table but Ineed to asign value to these variables to use in my code ahead they are the input values. So, for me it is required to assign value to the variable table coloumn. So, that these variables can be used ahead in the functions independently by the table indexing. Hope you get my point.

I need to get something like a loop and storing initial value to the correponding variable and later on these can be used as variable instead of set of character.

[Voss]

I think, regardless of how you need to use the variables, you can keep their values in the table, either as you had it originally or with the variable names as the row names.

For example, call a function using initial_val of fQ and QCsmd as inputs (using the variables as RowNames as my answer had):

my_function(V_table{'fQ','initial_val'},V_table{'QCsmd','initial_val'})

That's the same as if you made separate variables for those two things and then passed them to the function.

On the other hand, it may be convenient to bundle all the variables together in a structure. Here, starting from your original table, I'll make a structure of the variables' initial_val values:

% your original V_table:
V_table = table( ...
    {'Lser_B7Tx';'Lser_B7Rx';'QCsmd';'QLemb';'Lshu_B7';'fQ';'Cshu_B7';'QLsmd'}, ...
    [0;0;30;30;0;2000;0;30], ...
    [0.4;0.4;70;60;4;2500;0.01;60], ...
    [2;2;80;80;10;3000;2;80], ...
    'VariableNames',{'Variable','lb','initial_val','ub'});

args = [V_table.Variable num2cell(V_table.initial_val)].';
S = struct(args{:})

S = struct with fields:
    Lser_B7Tx: 0.4000
    Lser_B7Rx: 0.4000
        QCsmd: 70
        QLemb: 60
      Lshu_B7: 4
           fQ: 2500
      Cshu_B7: 0.0100
        QLsmd: 60

Then you can pass that structure to your functions (which, you could've passed the original table too), or you can pass just individual fields:

my_function(S.fQ,S.QCsmd)

(And obviously you could make similar structures for the lb and ub of the variables as well.)

And regardless of what the functions do to change the variables, you can re-assign the new value back where it belongs (in a structure or table) by returning the individual variable (or structure or table) back from the function and then doing the assignment.

Ultimately, it's unlikely that keeping 8 (or 24, with the lb and ub values) separate scalar variables is best, given that they're already organized in the table to begin with.

If it's unclear how to proceed, please share some code of the functions that need to operate with these variables.

[Aakriti Srivastava]

Hey Voss, thankyou and truly appreciate your help :). this is quite similar to what I want to do but unfortuantely I am getting some brace indexing error to make you undertand my problem clearly I am attaching my code snippet for the stage ahead.

Step1: Reading text file to create varibale tables with its corresponding values.That you have seen above like this

V_table =

8×4 table

Variable lb initial_val ub

_____________ ____ ___________ ____

{'Lser_B7Tx'} 0 0.4 2

{'Lser_B7Rx'} 0 0.4 2

{'QCsmd' } 30 70 80

{'QLemb' } 30 60 80

{'Lshu_B7' } 0 4 10

{'fQ' } 2000 2500 3000

{'Cshu_B7' } 0 0.01 2

{'QLsmd' } 30 60 80

Step2: Sort the variables with name L from the other section of text file

strt_ckt_idx = strfind(data,'INDQ');

end_ckt_idx = strfind(data,'DEF0P');

% node_array(1,1) = str2double(data(strt_ckt_idx(1)+5));

% node_array(1,2) = str2double(data(strt_ckt_idx(1)+7));

element_name_INDQ = extractBetween(data(strt_ckt_idx+5:end_ckt_idx),['L','=','{',' '],[' ','}',' ','Q={ QL'])

node_INDQ = extractBetween(data(strt_ckt_idx:end_ckt_idx),['INDQ',' '],[' ','ID="L']);

total_INDQ = length(strt_ckt_idx);

and created the table which looks something like this:

T =

3×3 table

element_name_INDQ node1_INDQ node2_INDQ

_________________ __________ __________

{'Lser_B7Tx'} 6 4

{'Lser_B7Rx'} 5 4

{'Lshu_B7' } 4 0

step 3: Now what I am trying to do is to store the value corresponding to this variable from the above V_table usimg the code shpwn below but I am getting the error .

for i = 1:total_INDQ

for j = 1:length(V_table.Variable)

if strcmp(V_table.Variable{j},element_name_INDQ{i})

args = [element_name_INDQ{i},V_table.initial_val{j}].'

% S_INDQ = struct(args{:})

end

end

end

Error using tabular/numArgumentsFromSubscript (line 111)

Brace indexing is not supported for variables of this type.

args = [element_name_INDQ{i},V_table.initial_val{j}].'

The step4 will be to perform mathematical and logical operation on the variable. Hope now I am clear with the question. But I really appreciate all your help. Thankyou. I need solution for this

y_cap = cellfun(@(x) w'*x, element_name_INDQ{i}, 'un', 0)

[Voss]

V_table = table( ...
    {'Lser_B7Tx';'Lser_B7Rx';'QCsmd';'QLemb';'Lshu_B7';'fQ';'Cshu_B7';'QLsmd'}, ...
    [0;0;30;30;0;2000;0;30], ...
    [0.4;0.4;70;60;4;2500;0.01;60], ...
    [2;2;80;80;10;3000;2;80], ...
    'VariableNames',{'Variable','lb','initial_val','ub'})

V_table = 8×4 table
      Variable        lb     initial_val     ub 
    _____________    ____    ___________    ____

    {'Lser_B7Tx'}       0        0.4           2
    {'Lser_B7Rx'}       0        0.4           2
    {'QCsmd'    }      30         70          80
    {'QLemb'    }      30         60          80
    {'Lshu_B7'  }       0          4          10
    {'fQ'       }    2000       2500        3000
    {'Cshu_B7'  }       0       0.01           2
    {'QLsmd'    }      30         60          80

% in your code, "T" comes from "data", but
% I don't have "data", so I hard-code T:
T = table( ...
    {'Lser_B7Tx';'Lser_B7Rx';'Lshu_B7'}, ...
    [6;5;4], ...
    [4;4;0], ...
    'VariableNames',{'element_name_INDQ' 'node1_INDQ' 'node2_INDQ'})

T = 3×3 table
    element_name_INDQ    node1_INDQ    node2_INDQ
    _________________    __________    __________

      {'Lser_B7Tx'}          6             4     
      {'Lser_B7Rx'}          5             4     
      {'Lshu_B7'  }          4             0     

% use ismember to get the index of each T.element_name_INDQ
% in V_table.Variable:
[~,idx] = ismember(T.element_name_INDQ,V_table.Variable)

idx = 3×1

1 2 5

% then build a structure of only those initial_val's:
args = [T.element_name_INDQ,num2cell(V_table{idx,'initial_val'})].';
S_INDQ = struct(args{:})

S_INDQ = struct with fields:
    Lser_B7Tx: 0.4000
    Lser_B7Rx: 0.4000
      Lshu_B7: 4

[Aakriti Srivastava]

You are amazing thank you so much. How can I learn all such way of handling data in MATLAB because this way didnt even comes up in my mind any suggestion?

[Aakriti Srivastava]

One more question S_INDQ I cant extract each element one by one for my next operation something like this

s_INDQ(1)

y_cap = cellfun(@(x) w'*x, S_INDQ(i), 'un', 0)

is it possible to store element in structure in such a way that I can access them element by element because mathematical operation to be performed on each element and to generate sparameter matrice corresponding to all elelements ?

[Voss]

You're welcome!

In general, I think knowing what your options are in any given situation is something that comes with experience, but getting into the habit of reading documentation (and learning how to understand what the documentation is telling you) definitely helps a lot!

Here's a documentation page about working with tables specifically:

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-table.html

And the "Related Topics" listed at the bottom of the page may be useful as well.

[Voss]

I'm not sure what this line

y_cap = cellfun(@(x) w'*x, S_INDQ(i), 'un', 0)

is intended to do.

[Aakriti Srivastava]

oh I am sorry what I have written is not of much sense.

But what I realized is that for fetching the value from the structure I need to know the name of the field of structure i.e S_INDQ.Lser_B7Tx but what I need is to extract the numerical values of these variables from the strcuture using indexing. Is it possible to do so? Because I need to write generalized code and this wont allow me to creae a loop extracting structure element.

[Voss]

(Setting up table and structure variables:)

V_table = table( ...
    {'Lser_B7Tx';'Lser_B7Rx';'QCsmd';'QLemb';'Lshu_B7';'fQ';'Cshu_B7';'QLsmd'}, ...
    [0;0;30;30;0;2000;0;30], ...
    [0.4;0.4;70;60;4;2500;0.01;60], ...
    [2;2;80;80;10;3000;2;80], ...
    'VariableNames',{'Variable','lb','initial_val','ub'});

T = table( ...
    {'Lser_B7Tx';'Lser_B7Rx';'Lshu_B7'}, ...
    [6;5;4], ...
    [4;4;0], ...
    'VariableNames',{'element_name_INDQ' 'node1_INDQ' 'node2_INDQ'});

[~,idx] = ismember(T.element_name_INDQ,V_table.Variable);
args = [T.element_name_INDQ,num2cell(V_table{idx,'initial_val'})].';
S_INDQ = struct(args{:});

You can use fieldnames to get the fields of a structure:

fields = fieldnames(S_INDQ)

fields = 3×1 cell array
    {'Lser_B7Tx'}
    {'Lser_B7Rx'}
    {'Lshu_B7'  }

and then loop over them:

for ii = 1:numel(fields)
    fprintf('field: %s',fields{ii})
    fprintf('value: %f',S_INDQ.(fields{ii}))
    % do whatever with S_INDQ.(fields{ii})
end

field: Lser_B7Tx

value: 0.400000

field: Lser_B7Rx

value: 0.400000

field: Lshu_B7

value: 4.000000

Or, in this case, loop over the values of T.element_name_INDQ (notice: not using structure S_INDQ here; using the tables T and V_table only):

for ii = 1:height(T)
    var_name = T.element_name_INDQ{ii}
    var_value = V_table{strcmp(V_table.Variable,var_name),'initial_val'}
end

var_name = 'Lser_B7Tx'

var_value = 0.4000

var_name = 'Lser_B7Rx'

var_value = 0.4000

var_name = 'Lshu_B7'

var_value = 4

And in that last case, it's convenient for V_table to have its RowNames be the names of the variables (going back to the idea in my original answer):

V_table.Properties.RowNames = V_table.Variable;
V_table.Variable = []

V_table = 8×3 table
                  lb     initial_val     ub 
                 ____    ___________    ____

    Lser_B7Tx       0        0.4           2
    Lser_B7Rx       0        0.4           2
    QCsmd          30         70          80
    QLemb          30         60          80
    Lshu_B7         0          4          10
    fQ           2000       2500        3000
    Cshu_B7         0       0.01           2
    QLsmd          30         60          80

because the syntax is cleaner:

for ii = 1:height(T)
    var_name = T.element_name_INDQ{ii}
    var_value = V_table{var_name,'initial_val'}
end

var_name = 'Lser_B7Tx'

var_value = 0.4000

var_name = 'Lser_B7Rx'

var_value = 0.4000

var_name = 'Lshu_B7'

var_value = 4

[Aakriti Srivastava]

You are truly amazing. Thank you so much. :)

[Voss]

You're welcome!

[Aakriti Srivastava]

Hy Voss, I have one issue with regexp if you have any information regarding this would you please help me out so the question is.

I want to read using regexp from port 12 to port 22 as

PORT 23 P=1 Z=50

PORT 12 P=2 Z=50 PIN_ID=CB7TX

PORT 13 P=3 Z=50 PIN_ID=CB7RX

PORT 14 P=4 Z=50 PIN_ID=CB66TX

PORT 15 P=5 Z=50 PIN_ID=CB25TX

PORT 16 P=6 Z=50 PIN_ID=CB25RX

PORT 22 P=7 Z=50 PIN_ID=CB66RX

This is the code I am using

[port_tokens2,port_match3] = regexp(data,'PORT\s+(\d+)\s+(\w+=\d)+\s+\w+=\d+\s','tokens','match')

Result I got

port_match3 =

1×7 cell array

Columns 1 through 5

{'PORT 23 P=1 Z=5…'} {'PORT 12 P=2 Z=50 '} {'PORT 13 P=3 Z=50 '} {'PORT 14 P=4 Z=50 '} {'PORT 15 P=5 Z=50 '}

Columns 6 through 7

{'PORT 16 P=6 Z=50 '} {'PORT 22 P=7 Z=50 '}

But I want to read PIN_ID = CBXXXX also so I used this expression

[port_tokens2,port_match3] = regexp(data,'PORT\s+(\d+)\s+(\w+=\d)+\s+\w+=\d+\s\w+=w+','tokens','match')

This is the result I got

port_match3 =

0×0 empty cell array

Would you please let me know what is wrong with my expression that I am not able to read the whole sentence.

[Voss]

There's a backslash missing before the last w you added. I included that backslash, and I removed the tokens because it doesn't seem like you need them. Does this do what you want now?

data = { ...
    'PORT 23 P=1 Z=50'
    'PORT 12 P=2 Z=50 PIN_ID=CB7TX'
    'PORT 13 P=3 Z=50 PIN_ID=CB7RX'
    'PORT 14 P=4 Z=50 PIN_ID=CB66TX'
    'PORT 15 P=5 Z=50 PIN_ID=CB25TX'
    'PORT 16 P=6 Z=50 PIN_ID=CB25RX'
    'PORT 22 P=7 Z=50 PIN_ID=CB66RX'
    };
port_match3 = regexp(data, ...
    'PORT\s+\d+\s+\w+=\d+\s+\w+=\d+\s\w+=\w+','match')

port_match3 = 7×1 cell array
    {0×0 cell}
    {1×1 cell}
    {1×1 cell}
    {1×1 cell}
    {1×1 cell}
    {1×1 cell}
    {1×1 cell}

port_match3{:}

ans =

  0×0 empty cell array

ans = 1×1 cell array
    {'PORT 12 P=2 Z=50 PIN_ID=CB7TX'}

ans = 1×1 cell array
    {'PORT 13 P=3 Z=50 PIN_ID=CB7RX'}

ans = 1×1 cell array
    {'PORT 14 P=4 Z=50 PIN_ID=CB66TX'}

ans = 1×1 cell array
    {'PORT 15 P=5 Z=50 PIN_ID=CB25TX'}

ans = 1×1 cell array
    {'PORT 16 P=6 Z=50 PIN_ID=CB25RX'}

ans = 1×1 cell array
    {'PORT 22 P=7 Z=50 PIN_ID=CB66RX'}

[Aakriti Srivastava]

Yes it does thankyou so much :) Great help.