Convert a cell in a field from string to number

Hi everyone. I'm having an issue as I'd like to graph some data but can't becuase it is in a string and dont know how to convert it to a number. I load the points from a tsv file with the following

%% Load xypts
points.samp{1}=tdfread('samp1xypts.tsv',';'); %load data points from particle tracking
points.samp{2}=tdfread('samp2xypts.tsv',';'); %load data points from particle tracking
points.samp{3}=tdfread('samp3xypts.tsv',';'); %load data points from particle tracking
points.samp{4}=tdfread('samp4xypts.tsv',';'); %load data points from particle tracking
points.samp{5}=tdfread('samp5xypts.tsv',';'); %load data points from particle tracking

I then put the data into cell arrays with the following

for i=1:1:length(frames)
  ind=find(points.samp{n}.Sparse_format_camera_coordinates_file(:,1)==frames(i));
    points.sorted{n}(i+1,1) = frames(i);
    points.sorted{n}(i+1,2) = points.samp{n}.Sparse_format_camera_coordinates_file(ind(1),3);
    points.sorted{n}(i+1,3) = points.samp{n}.Sparse_format_camera_coordinates_file(ind(2),3);
    points.sorted{n}(i+1,4) = points.samp{n}.Sparse_format_camera_coordinates_file(ind(3),3);
    points.sorted{n}(i+1,5) = points.samp{n}.Sparse_format_camera_coordinates_file(ind(4),3);
end

Which looks like this

I would like to graph three collums of this data using a 3D plot. Say for example I chose the first cell array I get the following error message

y = points.sorted{1}(:,2);
x = points.sorted{1}(:,3);
z = points.sorted{1}(:,5);
  p = plot3(x,y,z,'-g');

Error using plot3

Not enough input arguments.

Error in sortPoints (line 33)

p = plot3(x,y,z,'-g');

I suspect it is because the data is currently in string format as it works if I copy that data table into excel.... and then back into matlab again as a number and manually set up the vectors. Any help would be greatly appreciated. Thanks :)

Answer 1

[Walter Roberson]

I suspect it is because the data is currently in string format

x y z all need to be numeric for plot3() to work.

However, tdfread() should notice that all entries in the file are numeric other than the first row, and should create numeric output -- unless, that is, you have additional numeric rows that we cannot see from the diagram?

I recommend that you switch to using readmatrix() or readtable()

[Jack]

Yes when I initially set up the cell I add headings so I know which is which.

for n = 1:5
points.sorted{n}(1,1) = "Frame";
points.sorted{n}(1,2) = "Vertical disp";
points.sorted{n}(1,3) = "Horizontal disp";
points.sorted{n}(1,4) = "Vertical disp mirror";
points.sorted{n}(1,5) = "Horizontal disp mirror";
for i=1:1:length(frames)
  ind=find(points.samp{n}.Sparse_format_camera_coordinates_file(:,1)==frames(i));
    points.sorted{n}(i+1,1) = frames(i);
    points.sorted{n}(i+1,2) = points.samp{n}.Sparse_format_camera_coordinates_file(ind(1),3);
    points.sorted{n}(i+1,3) = points.samp{n}.Sparse_format_camera_coordinates_file(ind(2),3);
    points.sorted{n}(i+1,4) = points.samp{n}.Sparse_format_camera_coordinates_file(ind(3),3);
    points.sorted{n}(i+1,5) = points.samp{n}.Sparse_format_camera_coordinates_file(ind(4),3);
end
end

It now works when I comment out the headings. Is there a way that I can plot all the points except the top row so I can still have the headings?? Thanks for your help :)

[Walter Roberson]

I would suggest that you convert to using table() objects.