Test the variable type from file input

I recall a way in Verilog to test a char read in from a file (like a buffer, I believe) and then based on what that char is, proceed in a certain way.

My current file reading uses fscanf and reads in only numbers, but the users here sometimes user True/False for a line, and sometimes 0/1. An example of a line could be either:

Fruit Bananas True Potatoes False

~~ or ~~

Fruit Bananas 1 Potatoes 0

I'm trying to migrate toward 0/1, since I don't think Matlab recognizes True/False like python can. So I want to be able to read in either file type. If the scan returns a number (after the fruit type), then I proceed with numbers, if it returns a char or string, then I proceed for that. Does anyone have suggestions? Thanks!

&nbsp

EDIT: My actual input file looks more like this: (a mixture)

    VAR1   55.6
    VAR2   23
    VAR3   0
    VAR4 
    VAR5
    VAR6   -999
    VAR7   True
    VAR8   False
    VAR9   0
    VAR10  1

Answer 1

[per isakson]

Another approach

    fid = fopen('bananas.txt','r');
    cac = textscan( fid, '%s%s%s%s%s' );
    fclose( fid )
    isb = cellfun( @(str) logical( eval( lower( str ) ) ), cac{3} );

where bananas.txt contains the two lines

    Fruit Bananas True Potatoes False
    Fruit Bananas 1 Potatoes 0

Inspect isb

    >> whos isb
      Name      Size            Bytes  Class      Attributes
      isb       2x1                 2  logical

[per isakson]

Maybe you want to make sure that the column in questions only contains legal strings. eval is a bit scary since it tries to evaluate anything.

    assert( all( ismember( lower(cac{3}), {'1','0','true','false'} ) ) ...

[katerina]

I'm getting an error from this:

    hold = textscan(file,'%s%s');
    assign = cellfun(@(str) logical(eval(lower(str))),hold{2});

Here's the error:

    Error using get_data>@(str)logical(eval(lower(str))) (line 15)
    Error: Expression or statement is incomplete or incorrect.

    Error in get_data (line 15)
              assign = cellfun(@(str) logical(eval(lower(str))),hold{2});

My actual input file contains both numbers and T/F strings for the values of data. What could be the source of error here? Also, in hold{2} there are some empty slots where 0 was read in. Not sure if this could produce the error.

[per isakson]

VAR4 and VAR5 have no values. That causes the error.

    >> z = eval( lower('') )
    Error: Expression or statement is incomplete or incorrect.

[per isakson]

My "smart" on-liner doesn't work and cannot be fixed to work with empty and numerical values.

Lessons learned:

• Don't use specialized on-liners.
• Backward engineering of a simple example often results in erroneous requirements and consequently an answer, which doesn't apply to the real problem

Proposal: post a new question.

[per isakson]

• "I'm trying to migrate toward 0/1" &nbsp Why not stick with True/False? That makes the file more readable in the editor. What if '1' means numerical 1 for some other variable, e.g. VAR1
• "I don't think Matlab recognizes True/False like python" &nbsp I don't know Python well enough to understand the meaning of this statement.

Answer 2

[the cyclist]

There are ischar() and isnumeric() functions in MATLAB, to identify particular variable types, as well as the class() function.

Also, MATLAB will recognize true and false as logical values.

[katerina]

so if I read in "true" from a file, is there a value type I can use so that it will convert to 1 or 0?

[katerina]

I realize I could just read in the string and convert it if needed, but I'd like a clean way to discriminate between reading a number or "True"/"False".