how to Vectorize this for loop

Hi everyone i have wrote this code and i want to vectorize my code so it run faster here is the part of code i'm talking about

fileID = fopen('CANDec(day_1_9).txt','r');
text_data = textscan(fileID,'%s %s %s %s %s %s %s %s',1000,'delimiter',';');
hex=text_data(:,4);
signal_name=text_data(:,7);
decimal_wert=text_data(:,8);
for i =1:length(text_data{1,1})
    can.(signal_name{1,1}{i,1}).hex{i,1}=hex{1,1}{i,1};
    can.(signal_name{1,1}{i,1}).decimal_wert{i,1}=decimal_wert{1,1}{i,1};
end

hex , signal_name and decimal_wert are cells that i read from a .txt file (CANDec(day_1_9)). it has actually many million lines . it's means there is millions of signal_name but here i read just 1000 lines.

now i'm building a structure can and as the name for substructures i use signal_name dynamically. if you go in can-structure you see all signal_name as substructure and in these substruct you find again 2 substruct with the names hex and decimal_wer.

i hope you understand the code . so my goal is to vectorize this for loop . when i remove the for and vectorize it simply I will get this error :

Expected one output from a curly brace or dot indexing expression, but there were 1000 results.

i =1:length(text_data{1,1})
can.(signal_name{1,1}{i,1}).hex{i,1}=hex{1,1}{i,1};
can.(signal_name{1,1}{i,1}).decimal_wert{i,1}=decimal_wert{1,1}{i,1};

i hope you can help me with that.

Thank you

Answer 1

[Stephen23]

Try doing something like this:

[fid,msg] = fopen('CANDec(day_1_9).txt','rt');
assert(fid>=3,msg) % good practice to check the FID.
C = textscan(fileID,'%s%s%s%s%s%s%s%s',1000,'delimiter',';');
fclose(fid);
% Simpler to get the CONTENTS of the cell array:
hx = C{4}; % hex
sn = C{7}; % signal name
dw = C{8}; % decimal wert

I strongly recommend that you do not use nested structures, but instead store the signal name as data in its own right in a non-scalar structure, then your task is trivial:

can = struct('signalName',sn, 'hex',hx, 'decimalWert',dw)

And you can access the data in can using some very convenient sytaxes:

https://www.mathworks.com/help/matlab/matlab_prog/access-multiple-elements-of-a-nonscalar-struct-array.html

[Milad Ghobadi]

Thank you Stephen,

The reasone that I use these nested structures is that, the signal_names in this text-data will be repeated several time and every time with a new hex-value so i wanted to gather all this hex and decimal value under the name of corresponding signal-name in order to see them as I open a signal and thats the reasone that i used this dynamic naming ( can.(signal_name{i}) ) . It seems first like this:

can.(signal_1).hex(1)=AB

can.(signal_2).hex(1)=A2

can.(signal_3).hex(1)=C4

can.(signal_2).hex(2)=FE51

can.(signal_1).hex(2)=1DFA

can.(signal_2).hex(3)=1235

and after gathering all same signal together it should be like below:

can.signal_1.hex= AB , 1DFA

can.signal_2.hex=A2 , 1DFA , 1235

can.signal_3.hex=C4

I hope i could find a solution for this

Many Thanks

[Stephen23]

"I hope i could find a solution for this "

You would need to use loop, which is why accessing data in nested structures is usually not very convenient.

But what you show does not require nested structures, it would be much simpler to generate and access using a non-scalar structure:

can(1).hex  = {'AB','1DFA'};
can(1).name = 'signal_1';
can(2).hex  = {'A2', '1DFA', '1235'};
can(2).name = 'signal_2';
...

[Milad Ghobadi]

I cann't get it now can looks like this:

'B_UF' '374C' '704.17'

'B_IN' '025A' '29.94'

'B_UF' '00' '0'

'B_UF' 'BB' '124'

'B_STMAX' 'AA' '0'

'B_STMAX' 'F9' '249.0'

but it should be as shown as below:

'B_UF' ['374C' , '00' , 'BB'] [ '704.17' ,'0' , '124']

B_IN' '025A' '29.94'

B_STMAX' ['AA' , 'F9' ] ['0' , '249.0' ]

here is a sample of text-data:

1567081890.074777;2F357C0000943900;8000018A;352F;2-BYTE;Stat_N_BMU_10;BMU_UF_10;677.259795

1567081890.074777;2F357C0000943900;8000018A;007C;2-BYTE;Stat_N_BMU_10;BMU_IN_10;1.780835

1567081890.074777;2F357C0000943900;8000018A;3994;2-BYTE;Stat_N_BMU_10;BMU_UN_10;674.743694

[Stephen23]

sn = {  'B_UF'; 'B_IN'; 'B_UF'; 'B_UF'; 'B_STMAX'; 'B_STMAX'};
hx = {  '374C'; '025A';   '00';   'BB';      'AA';      'F9'};
dw = {'704.17';'29.94';    '0'; '1234';       '0';   '249.0'};
[fn,~,ix] = unique(sn);

Using nested structures:

can = struct();
for k = 1:max(ix)
    can.(fn{k}).hex = hx(k==ix);
    can.(fn{k}).dWt = dw(k==ix);
end

Checking:

>> can.B_UF.hex
ans = 
    '374C'
    '00'
    'BB'

Or with a non-scalar structure:

can = struct();
for k = 1:max(ix)
    can(k).name = fn{k};
    can(k).hex = hx(k==ix);
    can(k).dWt = dw(k==ix);
end

Checking:

>> can(3).name
ans =
B_UF
>> can(3).hex
ans = 
    '374C'
    '00'
    'BB'
 

I strongly recommend that you use a non-scalar structure. As well as the ease of access, consider what your code would do if one of the signal_names is not a valid fieldname.

[Milad Ghobadi]

Oh of coure old fashioned unique I almost forget about it . Great Thanks alot