Extract necessary fields values from .mat; Combining coordinates.

Hi,

I have matrix shown bellow:

I need to extract fields :

• fname
• bbpx-x1 , bbpx-y1, bbpx-x2,bbpx-y2 (combined in one row as [39 , 116, 569, 375].

So as a result I should get Output 8144*2 ;

'00001.jpg' [39 , 116, 569, 375]

'00002.jpg' [64 , 336, 159, 275]

... ....

'n.jpg' [n , n, n, n]

Thank you for your help!

Answer 1

[Luna]

Hi Vktor,

Try this below:

outPutCellArray = cell(numel(myStruct),2);
for i = 1:numel(myStruct)
 outPutCellArray{i,1} = myStruct(i).fname;
 outPutCellArray{i,2} = [myStruct(i).bbpx_x1,myStruct(i).bbpx_y1, myStruct(i).bbpx_x2, myStruct(i).bbpx_y2];
end

[Vktor Malic]

Thank you, works well!

[Luna]

Your welcome :)

[Vktor Malic]

Sorry, Luna, could you help me with one more thing, please.

How can I Convert cell array to table?

I tried to use C = cell2table(outPutCellArray); but it doesnt give result with coordinates in one column.

Thank you very much.

[Luna]

You can get the results of your desired column with below syntax for tables.

tableName.TableColumnName % gives the data of the corresponding column
tableName.Properties % shows the properties of the table such as VariableNames, Description, RowNames,etc.

For your case, C is a 8144x2 table. That means it has 2 columns named: object_bbox1 and object_bbox2 according to above picture. Please try below and read comments:

C.object_bbox2 % this will give you the entire second column of your table which is 8144x4 double array.
C.object_bbox2(1) % gives you the first row which is 1x4 vector

C.object_bbox1 % this will give you 8144x1 cell array filled with names of your jpg files.

You can read more about tables, here is the link: table

ps. If you only want to get 8144x4 double array you actually don't need to convert it into a table. You can get the second column with below code:

results = vertcat(outPutCellArray{:,2})

[Vktor Malic]

Sorry, maybe I didnt clearly explained my problem.

I am working with function that requirs values stored in Table.

I have no problem to convert Cell or Dataset to Table but when do it - data stored not in this way:

fname                    vehicle
'00001.jpg'         [39 , 116, 569, 375]
'00002.jpg'         [64 , 336, 159, 275]
...                          ....
'n.jpg'                 [n , n, n, n]

but this:

fname                    vehicle
'00001.jpg'         39      116     569     375
'00002.jpg'         64      336     159     275
...                                ....
'n.jpg'            n         n       n         n

So basicly now i have

 8144*2 Dataset

but I need to get 8144*2 Table value , like this:

 '00002.jpg'        [64 , 336, 159, 275]

Now a bit confused how to do it. :(

Thank you for help.

[Vktor Malic]

why when I convert it to Table it splits values from this [39 , 116, 569, 375] to this 39 116 569 375 in different columns

[Luna]

I really don't get what you mean by [39 , 116, 569, 375] and [39 116 569 375].

Because those are the same things 1x4 double arrays.

If you want them as string array with commas it will be a different thing.

[Vktor Malic]

Sorry, yes . I want them as sorting array with commas between

[Luna]

Btw, you are asking for a table but showing a dataset example in your variables window. These are also different things too.

[Luna]

Try this then,

outPutCellArray_new = cell(numel(myStruct),2);
for i = 1:numel(myStruct)    
    temp = [myStruct(i).bbpx_x1,myStruct(i).bbpx_y1, myStruct(i).bbpx_x2, myStruct(i).bbpx_y2];  
    outPutCellArray_new{i,1} = myStruct(i).fname;
    outPutCellArray_new{i,2} = strrep(strrep(strrep(num2str(temp),'   ',' '),'  ',' '),' ',',');
end

C = cell2table(outPutCellArray_new);

Answer 2

[Vktor Malic]

from this struct:

:

I need to extract:

 (fname; (bbox_x1,bbox_y1,bbox_x2,bbox_y2))

into the Table, so that (bbox_x1,bbox_y1,bbox_x2,bbox_y2) is string array with commas.