How to remove a range of rows from all nested structures of a parent structure?

Hi,

Imagine a 1x1 structure that contains a series of 10 structures that each contain 20x1 doubles. Is there a programmatic way to reduce all of these 10 structures to contain only 1 double, that being the first row's double in each case. In the end I would have 1x1 structure that contains 10 structures that each contain 1 double each.

Many thanks,

Darren.

Answer 1

[Stephen23]

s.a.fa = [1,2,3];
s.a.fb = [7,8,9];
s.a.fn = [4,5,6];
s.a

ans = struct with fields:
    fa: [1 2 3]
    fb: [7 8 9]
    fn: [4 5 6]

s.a = structfun(@(v)v(1),s.a, 'uni',0);
s.a

ans = struct with fields:
    fa: 1
    fb: 7
    fn: 4

[Darren Woods]

Hi Stephen,

Thanks for your assistance. This works perfectly for me.

To add some explanation for the curious reader, @(v)v(1) is taking each field within the structure and returning the first value. This works in my case on fields of [x,y double]. Further, if you wanted the full first row of each field, then you would use @(v)v(1,:). The comma,separated pair 'uni',0 specifies that the returned output can have any data type (the alternative is that the function has to return a column vector of scalars, e.g. the max value of each field, or the average value of each field, etc).

[Stephen23]

@Darren Woods: please remember to accept my answer if it helped you!

Answer 2

[Matt J]

s.a.f=[1,2,3];
s.b.f=[4,5,6];

s.a,s.b

ans = struct with fields:
    f: [1 2 3]

ans = struct with fields:
    f: [4 5 6]

for F=string(fieldnames(s)')

    s.(F)=structfun(@(f)f(1), s.(F),'uni',0);
    
end

s.a,s.b

ans = struct with fields:
    f: 1

ans = struct with fields:
    f: 4

[Darren Woods]

Thanks Matt,

In my case I have:

s.a.fa=[1,2,3];

...

s.a.fn=[4,5,6];

Actually I have s.a.fa = [10x1 double] and so on, and I want to loop through fa...fn with the logic you propose.

Running the solution above leads to the following output:

> Error using structfun

> Inputs to STRUCTFUN must be scalar structures.