Borrar filtros
Borrar filtros

Adding element within vector without overwriting the existing value

14 visualizaciones (últimos 30 días)
Alice
Alice el 16 de Feb. de 2015
Editada: Thorsten el 18 de Feb. de 2015
Is there a way of inserting values at points within an existing vector/array without overwriting the existing value?
So I have a list of values and I have a vector with positions in this list, is there a way of inserting the new values at these positions?
For example, is there a way of taking this list
expitemorder =
'Strong_Alt_Prime2.png'
'Strong_Alt_Target2.png'
'Strong_Alt_Prime1.png'
'Strong_Alt_Target1.png'
'Strong_Alt_Prime3.png'
'Strong_Alt_Target3.png'
'Strong_Alt_Prime4.png'
'Strong_Alt_Target7.png'
and inserting new/additional values without overwriting the existing values to get something like this
expitemorder =
'Strong_Alt_Prime2.png'
'Strong_Alt_Target2.png'
'NEW VALUE'
'Strong_Alt_Prime1.png'
'Strong_Alt_Target1.png'
'Strong_Alt_Prime3.png'
'Strong_Alt_Target3.png'
'NEW VALUE'
'Strong_Alt_Prime4.png'
'Strong_Alt_Target7.png'
So a way of adding new rows at predetermined positions within the list? Not just vertically concatenating the two.
Thanks

Respuestas (4)

Geoff Hayes
Geoff Hayes el 16 de Feb. de 2015
Alice - short of defining a special class to handle this sort of insertion into a list (i.e a linked list), I think that concatenation is one of the ways to go about creating your new list. So if
expitemorder = {...
'Strong_Alt_Prime2.png'
'Strong_Alt_Target2.png'
'Strong_Alt_Prime1.png'
'Strong_Alt_Target1.png'
'Strong_Alt_Prime3.png'
'Strong_Alt_Target3.png'
'Strong_Alt_Prime4.png'
'Strong_Alt_Target7.png'};
and you wish to insert a new string into the third position, then the code to do this would be
expitemorder = [expitemorder(1:2) ; 'NEW_VALUE' ; expitemorder(3:end)]
which produces
expitemorder =
'Strong_Alt_Prime2.png'
'Strong_Alt_Target2.png'
'NEW_VALUE'
'Strong_Alt_Prime1.png'
'Strong_Alt_Target1.png'
'Strong_Alt_Prime3.png'
'Strong_Alt_Target3.png'
'Strong_Alt_Prime4.png'
'Strong_Alt_Target7.png'
  2 comentarios
Alice
Alice el 16 de Feb. de 2015
Is it possible to use this to insert a new variable at multiple positions without repeating the previous sections of the list?
Geoff Hayes
Geoff Hayes el 16 de Feb. de 2015
Alice - please clarify what you mean by without repeating the previous sections of the list. What are the previous sections?

Iniciar sesión para comentar.


Thorsten
Thorsten el 16 de Feb. de 2015
X = {'asdf' 'foo' 'bar'};
n = 3; name = 'foooo';
X = {X{1:n-1} name X{n:end}};
  2 comentarios
Alice
Alice el 16 de Feb. de 2015
How would you implement this when n is a vector? So the resulting list would not have duplicated information from above?
Thorsten
Thorsten el 18 de Feb. de 2015
Editada: Thorsten el 18 de Feb. de 2015
There is probably a more elegant way w/o a for-loop, but this works:
X = {'asdf' 'foo' 'bar' 'yuck'};
pos = [2 4]; name = {'hi' 'this is new'};
for i = 1:numel(pos)
n = pos(i);
X = {X{1:n-1} name{i} X{n:end}};
end

Iniciar sesión para comentar.


Stephen23
Stephen23 el 16 de Feb. de 2015
Editada: Stephen23 el 17 de Feb. de 2015
This is easy using some MATLAB indexing and mat2cell, and just three lines of code:
X = [2,6]; % insert new element AFTER these elements.
A = {'Strong_Alt_Prime2.png',...
'Strong_Alt_Target2.png',...
'Strong_Alt_Prime1.png',...
'Strong_Alt_Target1.png',...
'Strong_Alt_Prime3.png',...
'Strong_Alt_Target3.png',...
'Strong_Alt_Prime4.png',...
'Strong_Alt_Target7.png'};
B = mat2cell(A,1,[X(1),diff(X),numel(A)-X(end)]);
B(2,:) = {'NEW VALUE'}; % new element
B = [B{1:end-1}];
When you run this code, the value of B will be:
B = {'Strong_Alt_Prime2.png'
'Strong_Alt_Target2.png'
'NEW VALUE'
'Strong_Alt_Prime1.png'
'Strong_Alt_Target1.png'
'Strong_Alt_Prime3.png'
'Strong_Alt_Target3.png'
'NEW VALUE'
'Strong_Alt_Prime4.png'
'Strong_Alt_Target7.png'}
Of course you can define X to be any positions for the new element, given the following conditions:
  • X cannot be empty.
  • all values in X are 0<=X<=numel(A).
  • the values are sorted in order.
  • zero places a new element before the first element.
  • accepts multiple new elements in the same location.

Ajay Pherwani
Ajay Pherwani el 16 de Feb. de 2015
expitemorder is a 8x1 cell array/vector , to update any element : - expitemorder{ any_index,1}='value';
  1 comentario
Thorsten
Thorsten el 18 de Feb. de 2015
No, this overwrites the value at any_index , but Alice asked for without overwriting the existing values.

Iniciar sesión para comentar.

Categorías

Más información sobre Logical en Help Center y File Exchange.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by