How do I get specific data using inpolygon in Matlab?

So,

I've written a code where I'm reading flight data from an excel sheet and trying to find all the flights within a particular bound using the inpolygon code. I to only record want the flight data which has all its cordinates within the polygons bound, and if it is not within the bound I don't want it to be recorded, but it isn't working...

This is the code:

clc;
clear all;
if exist('coords.mat','file')
    load coords
else
    lat = []; % latitude
    lon = []; % longitude 
    alt = []; % altitude
    spd = []; % speed
    flg = {}; % flight
    tim = []; % time
end
 lat1 = xlsread('plot.xlsx', 'C2:C86400');
 lon1 = xlsread('plot.xlsx', 'D2:D86400');
 alt1 = xlsread('plot.xlsx', 'E2:E86400');
 flg1 = xlsread('plot.xlsx', 'A2:A86400');
 lat10 = [6.6038,21.841667]; lon10 = [94.4166,62.375000];%P574 

% Save and continue
    save('coords.mat','lat','lon','alt','flg')
    pause(1)


%% Render the recorded data
% Prepare figure
d=37040;
load   coords %#ok<*UNRCH>
close  all

% Settings
centerLoc = [12.9716,77.5946]; % LEVC

% Prepare UTM scenario
mstruct      = defaultm('utm');
mstruct.zone = utmzone(centerLoc(1),centerLoc(2));
mstruct      = defaultm(mstruct);

% Plot land contours
SHPdir    = '.\SHPs\';
countries = shaperead([SHPdir 'ne_10m_admin_0_countries.shp'],...
            'Selector',{@(x) strcmpi(x,'es'),'foo'},'UseGeoCoords', true);
% Change 'ES.VC' for the provinces/states of your preference or use a RegExp
% for all provinces: @(x) strcmpi(x,'ES.VC') => @(x) ~isempty(regexpi(x,'^ES.*$'))
provinces = shaperead([SHPdir 'ne_10m_admin_1_states_provinces.shp'],...
            'Selector',{@(x) strcmpi(x,'ES.VC'),'region_cod'},'UseGeoCoords', true);
[x,y]     = mfwdtran(mstruct,[countries.Lat provinces.Lat],[countries.Lon provinces.Lon]);
[xc,yc]   = mfwdtran(mstruct,centerLoc(1),centerLoc(2));
 [x1,y1]= mfwdtran(mstruct,lat1,lon1);
[x10, y10]= mfwdtran(mstruct,lat10,lon10);
X = [x10,fliplr(x10)-d];
Y = [y10,fliplr(y10)];
[in,on] = inpolygon(x1,y1,X,Y);
% (in) contains the indices of the points inside the parallelogram
% (on) contains the indices of the points on the parallelogram

j =1;
i =1;
p = 1;
flightno = []  ; 
k = 0;
arr = 0;
for(flg1 = 1:86413)
    
   
while(i>1)
if(flg1(i)~=flg1(i-1))
    j =j+1;
    p = 1;
    if (k ==1)
        arr=arr+1;
        %plot flight no. (j - 1)
        flightno(arr) = (j-1); 
        
        
        k = 0;
    end
end
end

%checking
%define polygon and write check condition
if(x1(i)~= x1(~in))
if (p == 1)
k = 1; 

else
k = 0;
p = 0;
end
end


end

Can you help me out with this please?

Answer 1

[Guillaume]

I don't have the mapping toolbox and knows nothing about it, so possibly the problem is with your coordinate transformation code.

With regards to finding which flight is entirely within a polygon here is how to go about it:

journeys = readtable('plot.xlsx');  %much simpler than multiple xlsread

%your mapping toolbox code here. I've no idea if it's correct
%...

[journeys.x, journeys.y] = mfwdtran(mstruct, journeys.latitude, journeys.longitude);  %transform the flights latitude and longitude
in = inpolygon(journeys.x, journeys.y, X, Y);

[groupid, flights] = findgroups(journeys.flight);  %assign unique id to each flight and apply to rows of the table
isallin = splitapply(@all, in, groupid);  %are ALL points of the flight in the polygon? logical output

selectedflights = flights(isallin); %list of flights where all points are in the polygon
selectedjourneys = journeys(ismember(journey.flight, selectedflights), :);  %portion of the table with only the selected flights.

[harman bhaveja]

Hey Guillaume,

I had one doubt, like you had mentioned : isallin = splitapply(@all, in, groupid); %are ALL points of the flight in the polygon? logical output

How do I check/ plot all flights that have 70% and higher or 60% and higher or 80% and higher of the data is within the route?

[Guillaume]

inratio = splitapply(@(in) nnz(in)/numel(in), in, groupid);  %ratio of points in polygon to points in flight
selectedflights = flights(inratio >= .7);  %for flights that have 70% of their journey in the polygon

[harman bhaveja]

Thanks for the code but, the line containing nnz(in) is throwing an error...

[harman bhaveja]

This is the eroor I'm getting.

[Steven Lord]

Right before your cursor on line 69 you need to close the parentheses surrounding the anonymous function's input argument.

inratio = splitapply(@(in0) nnz(in)/numel(in), in, groupid);

[harman bhaveja]

Thanks for the code. Although the error is resolved, this code gives me 0 output. the table is blank and my map has nothing in it. I have attached the outputs.

[harman bhaveja]

this code gives me 0 output. the table is blank and my map has nothing in it. Could you please help me out with this? ://

[Guillaume]

The correct line should have been:

inratio = splitapply(@(in) nnz(in)/numel(in), in, groupid);  %ratio of points in polygon to points in flight

It's not my code that creates this empty table since my code does not create a m variable. All my variables have meaningful names so it's clear what their purpose is.

Anyway, the easiest way for you to find out what has gone wrong with your code is to debug it Step through the code one line at a time, see how the variables change and if they change the way you expected. If not, fix the line.

[harman bhaveja]

It worked thanks :)

Answer 2

[KSSV]

Refer this for demo: https://in.mathworks.com/matlabcentral/answers/454295-how-to-pick-the-points-in-meshgrid-within-a-outline

[harman bhaveja]

Will try, thanks.

[harman bhaveja]

Well this is the inpolygon function right?

I'm stuck at getting the flight data which has all its cordinates within the polygons bound, and if it is not within the bound I don't want it to be recorded

[KSSV]

Using inpolygon is straight forward. I don't know where you are stuck..? Attach your data tell us your problem.

[harman bhaveja]

Okay.

So, I'm using inpolygon to plot flight data within a particular bound. I only want to plot flights that are within the bound (paprallel or only inside it) and not the ones that have a few points within the bound and a few outside. So, what I thought was I'll write a code to record the list of flights which have data only within the bound (As asked in my question above) and nothing outside and then plot those flights separately later.

I'm attaching my code that plots my data (Untitled.m), the data (Plot.xlsx), the code that records the flight data (checkingcode.m) and plot that I'm getting (11.png, 22.png) below.