MATLAB: Hex to Signed Int conversion of 16bit values in a Table with data type ‘cell array of character vectors’

data acquisitiondigital signal processingEmbedded Coderhex2decMATLABtabletime series

I have a table as below having huge number of rows.

Time                Identifier           AC1     AC2     AC3     AC4
00:06:40.23             "300"           "6500"  "6900"  "6D00"  "7500" 
00:06:40.25             "100"           "B7FF"  "E5FF"  "7D10"  "0100"
  ...                    ...              ...     ...     ...     ...

The columns AC1 to AC4 are in 16bit 2's complement representation.

Need to convert all the values of those 4 columns in to signed decimal vlaue. The table shld be intact.

Any help is appreciated. Also, would like to know what would be a convenient way to have these kind of data other than in table, so that would be helpful for further processing. The data being sensor values wrt time.

Best Answer

temp = uint16(arrayfun(@(S) sscanf(S, '%x'), YourTable{:,3:6}));
output = reshape( typecast(temp(:), 'int16'), size(temp));

What kind of processing do you want to do on the entries? Possibly using a timetable() would be appropriate.

Related Solutions

MATLAB: Existing table, populate a column with string (receiving errors)

You are close, but you are trying to assign a character vector to a double variable (NaN = not a number). You can see that if you run the command summary(mytable).

You also do not need to put the text into a cell if you use the string data type.

See if you can get this code to work for your needs.

myArray = nan(5,2)
mytable = array2table(myArray);
mytable.Properties.VariableNames = {'colA', 'colB'};
mytable2 = convertvars(mytable,"colB",'string');
mytable2.colA(:) = 459;
mytable2.colB(:) = "words"

You say you have a lot of data. If the variables already exist, you could do something like this:

colA = nan(5,1);
colB = strings(5,1);
mytable = table(colA,colB);
mytable.colA(:) = 459; % just a random number, proof-of-concept that it works
mytable.colB(:) = "words" % this throws errors

MATLAB: Creating a 3D table (or equivalent)

Instead of making tables of tables, I recommend making a cell array of tables because stacking makes more sense in that case. For example

initTable1 = table('Size',[6,4],'VariableTypes',{'string','double','double','double'});
initTable2 = table('Size',[6,4],'VariableTypes',{'string','double','double','double'});
initTable3 = table('Size',[6,4],'VariableTypes',{'string','double','double','double'});
stackTable = {initTable1, initTable2, initTable3};

Now you can get the data using the index of the table in stack and the variable name.

stackTable{index_in_stack}.variableName

Best Answer

Related Solutions

MATLAB: Existing table, populate a column with string (receiving errors)

MATLAB: Creating a 3D table (or equivalent)

Related Question