INDEX EXCEEDS THE NUMBER OF ARRAY ELEMENTS. (2024)

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Kiet Ho am 25 Apr. 2024

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Bearbeitet: Voss am 25 Apr. 2024

Akzeptierte Antwort: Voss

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% Load the signal data from the text file using the load command with the -ascii option

x = load('Lab7data1.txt', '-ascii');

% Plot the signal

%figure;

%plot(x);

%xlabel('Sample');

%ylabel('Amplitude');

%title('Original Signal');

%grid on;

% Calculate the length of the signal in samples

signal_length = length(x);

num_periods = 100;

% Estimate the number of samples per period

samples_per_period = signal_length / num_periods;

% Check Nyquist condition

if samples_per_period >= 2

disp('Nyquist sampling rate is satisfied.');

else

disp('Nyquist sampling rate is not satisfied.');

end

% Calculate the current sampling rate

current_sampling_rate = 1 / samples_per_period;

% Estimate the down-sampling factor needed to reduce the sampling rate to

% the Nyquist

downsampling_factor = ceil(current_sampling_rate / 2);

% Down-sample the signal

downsampled_signal = x(1:downsampling_factor:end);

% Define the x-values for the down-sampled signal

downsampled_indices = 1:downsampling_factor:signal_length;

% Make sure the lengths match

if length(downsampled_indices) ~= length(downsampled_signal)

downsampled_indices = downsampled_indices(1:length(downsampled_signal));

end

% Interpolate the down-sampled signal to up-sample it

up_sampled_signal = interp1(downsampled_indices, downsampled_signal, 1:signal_length,'linear');

% Plot both the original and down-sampled signals

figure;

plot(1:signal_length, x, 'b', 'DisplayName', 'Original Signal');

hold on;

plot(downsampled_signal, 'ro', 'DisplayName', 'Down-sampled Signal');

plot(up_sampled_signal, 'g', 'DisplayName', 'Up-sampled Signal (Linear Interpolation)');

hold off;

xlabel('Sample');

ylabel('Amplitude');

title('Original vs Down-sampled Signal vs Up-sampled Signal');

legend('Location', 'best');

grid on;

3 Kommentare

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Voss am 25 Apr. 2024

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Please upload 'Lab7data1.txt' using the paperclip button.

Kiet Ho am 25 Apr. 2024

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Verschoben: Dyuman Joshi am 25 Apr. 2024

  • Lab7data1.txt

Here is the data. Thanks.

Voss am 25 Apr. 2024

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It's better to use size rather than length.

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Voss am 25 Apr. 2024

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Bearbeitet: Voss am 25 Apr. 2024

In MATLAB Online öffnen

My guess is that x is a matrix but your code is assuming it's a vector.

Example:

x = rand(2,232);

signal_length = length(x);

num_periods = 100;

% Estimate the number of samples per period

samples_per_period = signal_length / num_periods;

% Check Nyquist condition

if samples_per_period >= 2

disp('Nyquist sampling rate is satisfied.');

else

disp('Nyquist sampling rate is not satisfied.');

end

Nyquist sampling rate is satisfied.

% Calculate the current sampling rate

current_sampling_rate = 1 / samples_per_period;

% Estimate the down-sampling factor needed to reduce the sampling rate to

% the Nyquist

downsampling_factor = ceil(current_sampling_rate / 2);

% Down-sample the signal

downsampled_signal = x(1:downsampling_factor:end);

% Define the x-values for the down-sampled signal

downsampled_indices = 1:downsampling_factor:signal_length;

% Make sure the lengths match

if length(downsampled_indices) ~= length(downsampled_signal)

whos downsampled_indices downsampled_signal

disp('error happens here')

downsampled_indices = downsampled_indices(1:length(downsampled_signal))

end

Name Size Bytes Class Attributes downsampled_indices 1x232 1856 double downsampled_signal 1x464 3712 double

error happens here

Index exceeds the number of array elements. Index must not exceed 232.

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Voss am 25 Apr. 2024

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In MATLAB Online öffnen

  • Lab7data1.txt

Thank you for the data file.

x is a matrix:

x = load('Lab7data1.txt', '-ascii')

x = 8000x2

-0.5000 0.0807 -0.4999 0.0413 -0.4998 0.0020 -0.4996 -0.0370 -0.4995 -0.0767 -0.4994 -0.1157 -0.4993 -0.1547 -0.4991 -0.1937 -0.4990 -0.2321 -0.4989 -0.2704

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

which means that this line

% Down-sample the signal

downsampled_signal = x(1:downsampling_factor:end);

should be

% Down-sample the signal

downsampled_signal = x(1:downsampling_factor:end,:);

See the difference below.

signal_length = length(x);

num_periods = 100;

% Estimate the number of samples per period

samples_per_period = signal_length / num_periods;

% Check Nyquist condition

if samples_per_period >= 2

disp('Nyquist sampling rate is satisfied.');

else

disp('Nyquist sampling rate is not satisfied.');

end

Nyquist sampling rate is satisfied.

% Calculate the current sampling rate

current_sampling_rate = 1 / samples_per_period;

% Estimate the down-sampling factor needed to reduce the sampling rate to

% the Nyquist

downsampling_factor = ceil(current_sampling_rate / 2);

% Down-sample the signal

downsampled_signal = x(1:downsampling_factor:end)

downsampled_signal = 1x16000

-0.5000 -0.4999 -0.4998 -0.4996 -0.4995 -0.4994 -0.4993 -0.4991 -0.4990 -0.4989 -0.4988 -0.4986 -0.4985 -0.4984 -0.4983 -0.4981 -0.4980 -0.4979 -0.4978 -0.4976 -0.4975 -0.4974 -0.4973 -0.4971 -0.4970 -0.4969 -0.4968 -0.4966 -0.4965 -0.4964

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

downsampled_signal = x(1:downsampling_factor:end,:)

downsampled_signal = 8000x2

-0.5000 0.0807 -0.4999 0.0413 -0.4998 0.0020 -0.4996 -0.0370 -0.4995 -0.0767 -0.4994 -0.1157 -0.4993 -0.1547 -0.4991 -0.1937 -0.4990 -0.2321 -0.4989 -0.2704

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

% Define the x-values for the down-sampled signal

downsampled_indices = 1:downsampling_factor:signal_length;

% Make sure the lengths match

if length(downsampled_indices) ~= length(downsampled_signal)

downsampled_indices = downsampled_indices(1:length(downsampled_signal))

end

% Interpolate the down-sampled signal to up-sample it

up_sampled_signal = interp1(downsampled_indices, downsampled_signal, 1:signal_length,'linear');

% Plot both the original and down-sampled signals

figure;

plot(1:signal_length, x, 'b', 'DisplayName', 'Original Signal');

hold on;

plot(downsampled_signal, 'ro', 'DisplayName', 'Down-sampled Signal');

plot(up_sampled_signal, 'g', 'DisplayName', 'Up-sampled Signal (Linear Interpolation)');

hold off;

xlabel('Sample');

ylabel('Amplitude');

title('Original vs Down-sampled Signal vs Up-sampled Signal');

legend('Location', 'best');

grid on;

INDEX EXCEEDS THE NUMBER OF ARRAY ELEMENTS. (7)

Kiet Ho am 25 Apr. 2024

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It works. Thank you so much for your help.

Voss am 25 Apr. 2024

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Bearbeitet: Voss am 25 Apr. 2024

You're welcome! Any questions, let me know.

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Translated by INDEX EXCEEDS THE NUMBER OF ARRAY ELEMENTS. (10)

INDEX EXCEEDS THE NUMBER OF ARRAY ELEMENTS. (11)

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INDEX EXCEEDS THE NUMBER OF ARRAY ELEMENTS. (2024)

FAQs

What does the error index exceeds the number of array elements mean? ›

The error means you are trying to index a vector/array element that does not exist in your variable. Specifically, your error message is telling you your array has a single element, and your index is >1.

What is error index exceeds number of array elements 0 in Matlab? ›

Accepted Answer

Ran in: Your variable data contains 3 empty cells, so you are getting an indexing error because you are trying to index into it using a value greater than 0. Note that, in MATLAB, you will get an error if you try to use 0 as well. Index exceeds the number of array elements.

How do you find the index number of an element in an array? ›

JavaScript Array findIndex()

The findIndex() method executes a function for each array element. The findIndex() method returns the index (position) of the first element that passes a test. The findIndex() method returns -1 if no match is found.

How do you change the index number of an array? ›

Using the splice() Method

The splice() method is used to change an array by adding, removing, or replacing elements. This method modifies the original array. The first argument of the splice() method is the start index, which is the index at which to start changing the array.

What is the array element limit? ›

Java array size and length

The theoretical maximum Java array size is 2,147,483,647 elements. To find the size of a Java array, query an array's length property. The Java array size is set permanently when the array is initialized. The size or length count of an array in Java includes both null and non-null characters.

What does index out of array mean? ›

The error message "Index was outside the bounds of the array" typically indicates that a program or software is trying to access an element or value from an array using an index that is invalid or out of range. This can occur when the software encounters unexpected data or a programming error.

What does it mean for an array to be zero indexed? ›

Zero-based array indexing is a way of numbering the items in an array such that the first item of it has an index of 0, whereas a one-based array indexed array has its first item indexed as 1. Zero-based indexing is a very common way to number items in a sequence in today's modern mathematical notation.

How do you find the maximum value of an array index in MATLAB? ›

M = max( A ,[], "all" ) finds the maximum over all elements of A . M = max( A ,[], dim ) returns the maximum element along dimension dim .

What is index number in array? ›

Element index: It is the sequential number (index/key) assigned to the element where the first element of the array is assigned 0. It can also be defined as the number of elements prior to that particular element in the array. Size of a single element: Elements in the array need to be of the same data type or object.

How do you get the number of elements in an array? ›

The sizeof() operator in C++ returns the size of the passed variable or data in bytes, plus the total number of bytes required to store an array. So, if we divide the size of the array by the size acquired by each element of the same, we can get the total number of elements present in the array.

How do you get the element at the index of an array? ›

The indexOf() method of Array instances returns the first index at which a given element can be found in the array, or -1 if it is not present.

How do you replace an index value in an array? ›

The array type in JavaScript provides us with the splice() method that helps us in order to replace the items of an existing array by removing and inserting new elements at the required/desired index. Syntax: Array. splice(start_index, delete_count, value1, value2, value3, ...)

How do I change the index value in an array list? ›

The most common way to replace an element in Java ArrayList is to use the set (int index, Object element) method. The set() method takes two parameters: the index of the existing item and the new item. The index of an ArrayList is zero-based.

How do you remove an array index by value? ›

To delete an index inside an array in JavaScript, you can use the splice() method. In the example code, splice(2, 1) means remove 1 element at index 2. The first argument 2 is the starting index, and the second argument 1 is the number of elements to remove.

What does indexing error mean? ›

What does it mean? An IndexError means that your code is trying to access an index that is invalid. This is usually because the index goes out of bounds by being too large. For example, if you have a list with three items and you try to access the fourth item, you will get an IndexError.

How do I fix an array index out of bounds exception? ›

To avoid the ArrayIndexOutOfBoundsException , the following should be kept in mind:
  1. The bounds of an array should be checked before accessing its elements.
  2. An array in Java starts at index 0 and ends at index length - 1 , so accessing elements that fall outside this range will throw an ArrayIndexOutOfBoundsException .
May 30, 2024

What does too many indices for array mean? ›

The indexerror: too many indices for an array means that you have a declared an array in a different dimension and trying to index it in another dimension. For example, suppose you have declared a numpy array in a single dimension and try to access the elements of an array in 2 dimensional.

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