Numeric and Alphabetic symbols in same matrx

I'm working on a model to use matlab as graphical representation for other model. Therefore I'd like to have a matrix that can be updated with b开发者_如何学Pythonoth letters and numbers. Numbers will represent a speed while for example '-' may represent a empty section. In the matlab documentation and on internet I found a lot of interesting tips, but not what I need. Thanks in advance!

You cannot represent data of numeric type (integers/floating points) and data of char type in a matrix. However, you can, use cells, which are similar to matrices, and can hold different data types in each cell. Here's an example.

A={[1 2 3],'hello';'world',[4,5,6]'}

A = 

    [1x3 double]    'hello'     
    'world'         [3x1 double]

Here the first cell contains a row vector, the second and third cells contain strings and the fourth cell contains a column vector. Indexing into a cell is similar to that of arrays, with one minor difference: use {} to group the indices. e.g., to access the element in the second row, first column, do

A{2,1}

ans =

world

You can also access an element of an array inside a cell like

A{2,2}(2)

ans = 

    5

If you're wanting to store mixtures of numeric and character type data, yoda has the correct suggestion: use cell arrays.

However, based on the example you described you may have another option. If the character entries in your matrix are there for the purpose of identifying "missing data", it may make more sense to use a purely numeric matrix containing unique values like NaN or Inf to identify data points that are empty or where data is not available.

When performing operations on your matrix, you would then have to index only elements that are finite (using, for example, ISFINITE) and perform your calculations on them. There are even some functions in the Statistics Toolbox that will perform operations ignoring NaN values. This may be a cleaner way to go since you can keep your matrix as a numeric type ('single' or 'double' precision) instead of having to mess with cell arrays.