How to split array into sub arrays?

how to split principal vector "a" into sub vectors a1, a2, a3 and a4

exemple:

a=[1 3 5 8 11 12 15 17 18 19 20 21 24 29 31 32 33 34 35 36 38 39];

a1=[1 3 5 8];

a2=[11 12 15 17 18 19 20];

a3=[21 24 29];

a4=[31 32 33 34 35 36 38 39];

thnkx

[Stephen23]

What is the rule for splitting into those vectors?

For example:

• why is 20 in a2 and not in a3 ?
• why is 21 in a3 and not in a2 ?

Note that creating numbered variables is not a good approach. Much better to use a cell array.

[benghenia aek]

I want to split the big array "a" into:

a1 "the numbers between 0 and 10"

a2 "the numbers between 11 and 20"

a3 "the numbers between 21 and 30"

and make it into cell arrays

[Dyuman Joshi]

Any updates, @benghenia aek?

Answer 1

[Dyuman Joshi]

a = [1 3 5 8 11 12 15 17 18 19 20 21 24 29 31 32 33 34 35 36 38 39 69].';

%bin the data into groups of 10
k = findgroups(floor((a-1)/10));
z = accumarray(k, a, [], @(x) {x.'})

z = 5×1 cell array
    {[                1 3 5 8]}
    {[   11 12 15 17 18 19 20]}
    {[               21 24 29]}
    {[31 32 33 34 35 36 38 39]}
    {[                     69]}

Answer 2

[Matt J]

a = [1 3 5 8 11 12 15 17 18 19 20 21 24 29 31 32 33 34 35 36 38 39];

G=findgroups(discretize(a,[0:10:max(a)+10],'Include','right'));

z=splitapply(@(x){x}, a, G)

z = 1x4 cell array
    {[1 3 5 8]}    {[11 12 15 17 18 19 20]}    {[21 24 29]}    {[31 32 33 34 35 36 38 39]}

[Dyuman Joshi]

splitapply() won't work if there is a gap in the data -

a = [1 3 5 8 11 12 15 17 18 19 20 21 24 29 31 32 33 34 35 36 38 39 69];

G=discretize(a,[0:10:max(a)+10],'Include','right');

z=splitapply(@(x){x}, a, G)

Error using splitapply
For N groups, every integer between 1 and N must occur at least once in the vector of group numbers.

[Matt J]

Small modification,

a = [1 3 5 8 11 12 15 17 18 19 20 21 24 29 31 32 33 34 35 36 38 39 69];

G=findgroups(discretize(a,[0:10:max(a)+10],'Include','right'));

z=splitapply(@(x){x}, a, G)

z = 1x5 cell array
    {[1 3 5 8]}    {[11 12 15 17 18 19 20]}    {[21 24 29]}    {[31 32 33 34 35 36 38 39]}    {[69]}