How to read numeric data with different number of columns

I would like to read in the numeric data below into 3 different arrays:

0 0.2 0.5 0.8 into "a_on_t"

4 10 into "Ri_on_t" and

2 5 10 into "2c_on_a"

I code just hard code these in, but it would be better to read them from a file. I was thinking of constructing the file like so:

% Header info describing file contents
% Rows correspond to:
% a / t
% Ri / t
% 2c / a 
0	0.2	0.5	0.8
4	10
2	5	10

or, alternatively:

% Header info describing file contents
a_on_t	0	0.2	0.5	0.8
Ri_on_t	4	10
2c_on_a	2	5	10

I would like to be able to extract the names of the arrays in which to store the data from the file and, of course, to extract the numbers from the file. As I am using R2018a I don't have access to the table reading functions. I have tried putting the data into a cell using textscan, but I just end up with a list (or 1D array) of numbers. I definitely need the numbers, I could hard code the names of the arrays for now.

fgetl might be a possibility, but then there is the difficulty of extracting the data from a cell and converting characters to numbers.

Am I missing something obvious? This seems much more difficult than it should be.

Thanks!

[Jon]

Correction: It appears that readtable is available in R2018b. Whether that makes any difference, I'm not so sure.

[Adam Danz]

readtable was introduced in R2013b but features have been added in several releases since then.

[Stephen23]

"Am I missing something obvious? This seems much more difficult than it should be."

https://www.mathworks.com/matlabcentral/discussions/tips/849901-tutorial-why-variables-should-not-be-named-dynamically-eval

[Jon]

@Stephen23. Thanks for the link about naming of variables. I have bookmarked this and intend to read it when we have a rainy day and I have a bit of spare time. Looks like a pretty contentious subject! Nor have I ever really understood the eval command, so hope to learn something new.

regards

Jon

Answer 1

[Adam Danz]

Is this what you are looking for?

file = "data.txt"; 
t = readtable(file, 'ReadRowNames',true,"Delimiter",'\t')

t = 3x4 table
               Var1    Var2    Var3    Var4
               ____    ____    ____    ____

    a_on_t      0      0.2     0.5     0.8 
    Ri_on_t     4       10     NaN     NaN 
    2c_on_a     2        5      10     NaN 

The data file contains comment lines that begin with "%", contains row names, and is tab delimited.

% Header info describing file contents

a_on_t 0 0.2 0.5 0.8

Ri_on_t 4 10

c_on_a 2 5 10

[Jon]

Hi Adam. After discovering that readtable was, in fact, available, I came up with something similar, but I re-arranged my input data into columns and used "ReadVariableNames". I prefer your solution where you have used "readrownames", which I was unaware of - it makes the input file easier to read.

Thanks for your help.

Jon