如何正确获得Matlab数据点标签？ 第2部分

Question

I've created some Matlab code which anyone helping can run and see the problem.

When I run the following code, for each data point on my plot I seem to get all 15 labels instead of only 1 specific label.

So how do I get the Matlab data point labels correct for the following code?

Based on the the suggestions from my previous question , I did the following:

I replaced these two lines of code:

labels = num2str(test_vector_label,'F%d');
labels_cell = cellstr(labels);

With this line of code as suggested:

labels_cell = strread(num2str(test_vector_label),'%s');

Now there are two follow-up questions:

1) A warning appears stating that I should use textscan instead of strread :

labels_cell = textscan(num2str(test_vector_label),'%s');

Then when I use textscan as in the above line of code above, I get an error?

"Error using text Cell array of strings may only contain string and numeric matrices"

"Error in Code_Test (line 46) text(x_val,y_val,labels_cell,'horizontal','left', 'vertical','bottom')"

2) How do I put a letter in front of the number labels? For example, in the original code I had put letter F followed by a number?

%--------------Randomly select training and testing data.-----------
num_data = 35;

data_idx = 1:35;

train_data_idx_tmp = randsample(num_data,20)

train_dataRand_idx = sort(train_data_idx_tmp)

% Lia = ismember(A,B) returns an array the same size as A, containing 1 (true) 
% where the elements of A are found in B, and 0 (false) elsewhere.
test_data_idx_tmp = ismember(data_idx,train_dataRand_idx)

test_dataRand_idx = data_idx(~test_data_idx_tmp)'

% Check to see if training and test data index are exclusive. 
check_train_test_idx = ismember(train_dataRand_idx,test_dataRand_idx)

%--------------------------------------------------------------------------
% Testing stage.
test_vector = test_dataRand_idx; %Select randomly obtained testing data.

% Training stage.
train_vector = train_dataRand_idx; %Select randomly obtained training


x_val = [1:15];

y_val = 2*[1:15];

plot(x_val,y_val,'or','MarkerFaceColor','r')
grid on


%Put specific data point labels on plots.
test_vector_label = test_vector';
labels = num2str(test_vector_label,'F%d');   
labels_cell = cellstr(labels);
text(x_val,y_val,labels_cell,'horizontal','left', 'vertical','bottom')

Answer 1

textscan returns a cell array and not an array of strings. Try the following

labels_cell = textscan(num2str(test_vector_label),'%s');
labels_cell = strcat('F',labels_cell{1});