类型如何在MATLAB / Octave中工作？

Question

I've got a thing called allWords, which for some reason I have to index with curly brackets:

allWords{1}
ans =

  9x1 struct array containing the fields:

    img
    groundTruth

In it are nine images of handwritten characters, and if I assign each of them to a variable:

a=allWords{1}(1).img
b=allWords{1}(2).img
c=allWords{1}(3).img
d=allWords{1}(4).img
e=allWords{1}(5).img
f=allWords{1}(6).img
g=allWords{1}(7).img
h=allWords{1}(8).img
i=allWords{1}(9).img

And do this, then I can see the handwritten word as it was before it was chopped up.

imshow([a b c d e f g h i])

That's much nicer than my previous version:

# the first word
n=1
l=length(allWords{n})
for i = 1:l, subplot(1,l,i); imshow(allWords{n}(i).img); end;

Which puts unnecessary spaces in between the images.

However, it's very ugly, how do I generalize it and simplify it?

This looked like the obvious thing to do, but waah waah, not good enough for sodding Matlab:

 imshow(allWords{1}.img)

Stupid heap. Has anyone got any tips for finding out the types of things, or working out what types will magically turn into other types and what won't or how the bloody indexing works or any sort of logical explanation why this whole vile mess ended up this way?

Answer 1

Try:

img = cat(2, allWords{1}(:).img);
imshow(img)

Some explanation:

allWords is a cell array. As far as what you've shown, it contains at least one element.

The first element allWords{1} is a structure array of size 9x1 (ie an array where each element is a struct). Each structure has two fields img and groundTruth .

Now when you access allWords{1}.img , this will return a comma-separated list, which basically expands into x1,x2,... . So we can combine them into a matrix as [allWords{1}.img] , assuming the sizes are compatible.

End result:

imshow([allWords{1}.img])