How can I extract non-consecutive indices from a vector?
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Ray Smith
il 5 Apr 2020
In 5.2 Extracting Multiple Elements, Further practice "Indices can be non-consecutive numbers. Try extracting the first, third, and sixth elements of density." How?
14 Commenti
Edward li
il 25 Ago 2023
Could someone explain the logic behind the parenthese and the brackets. like why is it in that order and what does each mean?
Voss
il 19 Dic 2023
@Edward li: In this case, the parentheses are used for indexing, and the square brackets are used for array concatenation. [1,3,6] concatenates the scalars 1, 3, and 6 into a single vector, and density([1,3,6]) gets the elements of density at the indices stored in that vector.
See the Special Characters section of this page for more information:
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David Hill
il 5 Apr 2020
If you have a density array (d), then to extract the 1,3,6 elements:
extracted_elements=d([1,3,6]);
20 Commenti
Image Analyst
il 12 Lug 2023
@Viktoriia observe it working without commas below:
d = 10 : 10 : 60 % Sample data vector.
extracted_elements = d([1 3 6]) % Get only some of the elements
If you execute that code on your computer what do you see? If you executed different code than above, without commas, then what was that code?
Più risposte (8)
Kakasaheb Nikam
il 12 Mag 2020
density(3)
% extract third element
when we use [ ] square bracket, it extracting specific index position values.
so answer is
extracted_elements = density( [ 1, 3, 6 ] );
2 Commenti
Diogo Teixeira Fernandes
il 28 Set 2021
extracted_elements=density([1,3,6])
it worked for me
0 Commenti
Girish Pal
il 2 Set 2020
p = density(1), density(3), density(6)
2 Commenti
Stephen23
il 2 Set 2020
Modificato: Stephen23
il 2 Set 2020
While this does literally what the question requests "...extract non-consecutive indices from a vector", it only assigns the first of the comma-separated list to p, which is unlikely to give the desired effect, nor is it likely to be what the homework task requires.
Ahmed
il 7 Mar 2024 alle 18:07
Extracting Multiple Elements
Instructions are in the task pane to the left. Complete and submit each task one at a time.
This code sets up the activity.
data = [3 0.53 4.0753 NaN;18 1.78 6.6678 2.1328;19 0.86 1.5177 3.6852;20 1.6 3.6375 8.5389;21 3 4.7243 10.157;23 6.11 9.0698 2.8739;38 2.54 5.30023 4.4508]
density = data(:,2)
x = density([1,3,6])
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Parvin
il 14 Mar 2024 alle 11:33
This code sets up the activity.
data = [3 0.53 4.0753 NaN;18 1.78 6.6678 2.1328;19 0.86 1.5177 3.6852;20 1.6 3.6375 8.5389;21 3 4.7243 10.157;23 6.11 9.0698 2.8739;38 2.54 5.30023 4.4508]
To extract the first, third, and sixth elements of density, use [1 3 6] as an index.
density = [1 3 6]
data(density)
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