Geographical binning with HISTA not creating squares

Hello everybody!

My data contains latitude, longitute, time and multiple other variables. I need to bin this data for my needs.

>> head(w_files{1})

             time               lon       lat      pci_lte    sinr_lte    cinr_lte    rsrp_lte    prb_dl_lte    prb_ul_lte    bler_dl_lte    bler_ul_lte    mod_dl_0_lte    mod_dl_1_lte    mod_ul_lte    earfnc_dl_lte    earfnc_ul_lte    tp_mac_dl_lte    tp_mac_ul_lte    tp_pdsch_lte    tp_pusch_lte    tp_pdcp_dl_lte    tp_pdcp_ul_lte        tm            tx_rx        bw_dl_lte    bw_ul_lte       band          ca_dl         ca_ul                ca_comb              
    _______________________    ______    ______    _______    ________    ________    ________    __________    __________    ___________    ___________    ____________    ____________    __________    _____________    _____________    _____________    _____________    ____________    ____________    ______________    ______________    __________    _____________    _________    _________    ___________    __________    __________    _________________________    

    2020-12-08 11:48:13.000    14.563    50.035      NaN        NaN          0          NaN           NaN           NaN           NaN            NaN         {0×0 char}      {0×0 char}     {0×0 char}         NaN               NaN              NaN              NaN              NaN            NaN             NaN               NaN          {0×0 char}    {0×0 char   }       NaN          NaN       {0×0 char }    {0×0 char}    {0×0 char}    {0×0 char               }    
    2020-12-08 11:48:14.000    14.563    50.035      374        NaN          0          -61         41.49          0.74             9              5         {'256QAM'}      {0×0 char}     {0×0 char}        6200             24200           238.43            0.002           238.43          0.327               0                 0          {'TM4'   }    {'MIMO(4x2)'}        10           10       {'Band 20'}    {'3CA'   }    {'NonCA' }    {'Band 20+Band 7+Band 3'}     
    2020-12-08 11:48:15.000    14.563    50.035      374         11          0          -61          43.3           0.7             7              2         {'256QAM'}      {0×0 char}     {0×0 char}        6200             24200           256.08            0.002           256.08          0.314               0                 0          {'TM4'   }    {'MIMO(4x2)'}        10           10       {'Band 20'}    {'3CA'   }    {'NonCA' }    {'Band 20+Band 7+Band 3'}   
    2020-12-08 11:48:16.000    14.563    50.035      374         10          0          -61         44.31          0.69             6              2         {'256QAM'}      {0×0 char}     {0×0 char}        6200             24200            257.2            0.001            257.2          0.324               0                 0          {'TM4'   }    {'MIMO(4x2)'}        10           10       {'Band 20'}    {'3CA'   }    {'NonCA' }    {'Band 20+Band 7+Band 3'}    
    2020-12-08 11:48:17.000    14.563    50.035      374         10          0          -61         43.57          0.81             6              0         {'256QAM'}      {0×0 char}     {0×0 char}        6200             24200           252.94            0.001           252.94          0.357               0                 0          {'TM4'   }    {'MIMO(4x2)'}        10           10       {'Band 20'}    {'3CA'   }    {'NonCA' }    {'Band 20+Band 7+Band 3'}    
    2020-12-08 11:48:18.000    14.563    50.035      374          9          0          -63         44.93          0.79             7              0         {'64QAM' }      {0×0 char}     {0×0 char}        6200             24200           226.24            0.002           226.24           0.35               0                 0          {'TM4'   }    {'MIMO(4x2)'}        10           10       {'Band 20'}    {'3CA'   }    {'NonCA' }    {'Band 20+Band 7+Band 3'}    
    2020-12-08 11:48:19.000    14.563    50.035      374          7          0          -62         44.45           0.8            11              0         {'16QAM' }      {0×0 char}     {0×0 char}        6200             24200           191.17            0.002           191.17          0.359               0                 0          {'TM4'   }    {'MIMO(4x2)'}        10           10       {'Band 20'}    {'3CA'   }    {'NonCA' }    {'Band 20+Band 7+Band 3'}   
    2020-12-08 11:48:20.000    14.563    50.035      374          2          0          -66         44.18          0.82            12              2         {'16QAM' }      {0×0 char}     {0×0 char}        6200             24200            177.6            0.002            177.6          0.372               0                 0          {'TM4'   }    {'MIMO(4x2)'}        10           10       {'Band 20'}    {'3CA'   }    {'NonCA' }    {'Band 20+Band 7+Band 3'} 

I am using HISTA to find a 20x20 meters grid and applying it on the data sets.

[latbin, lonbin] = hista(w_files{ii}.lat,w_files{ii}.lon,0.0004);% bin at 20x20m,hista binning + computing binsID
[w_files{ii}.latEq, w_files{ii}.lonEq] = grn2eqa(w_files{ii}.lat,w_files{ii}.lon);% Convert coordinates to equidistant cartesian coordinates
[latbinEq, lonbinEq] = grn2eqa(latbin, lonbin);% Convert coordinates to equidistant cartesian coordinates
dist = pdist2([w_files{ii}.lonEq,w_files{ii}.latEq],[lonbinEq, latbinEq]);% Compute distance between each coordinate and each bin-center
[~, w_files{ii}.bin20] = min(dist,[],2);% Add bin ID numbers to table

When I run a figure with plot_google_map I am not getting squares but rectangles. Right now, I am not sure if I am just displaying it wrong or I have made some mistake in the binning. I have added one sample file for you guys to try. (You will need plot_google_map function to have the map picture but this issue is clearly visible without it as well).

   figure()
   hold on
   scatter(lonbin, latbin, 200, 1:numel(lonbin), 'Marker','*','LineWidth',2) % bin centers
   scatter(w_files{ii}.lon,w_files{ii}.lat, 50,w_files{ii}.bin20,'filled')
   cmap = colorcube(255);
  colormap(cmap(1:end-10,:))
   xlabel('longitude'); ylabel('latitude')
   latbinUnq = unique(latbin); 
   lonbinUnq = unique(lonbin);
   set(gca, 'xtick', lonbinUnq(2:end)-diff(lonbinUnq)/2,'ytick',latbinUnq(2:end)-diff(latbinUnq)/2)
   grid on
  plot_google_map('Scale',2,'resize',2,'ShowLabels',0)%google_plot settings

What do you think? If you think you know the answer, please be very specific because I am a beginner and I might be dumb.

Answer 1

[Abhinaya Kennedy]

Hi Karel,

The "daspect([1 1 1])" function sets the data aspect ratio to be equal in all directions, but it might not always result in square grids on the plot if the x-axis and y-axis data units are different. Here's how you can modify "daspect" to get square grids:

Option 1: Adjust data units

Analyze your data and see if the x and y-axis units are the same. If not, consider rescaling your data to have the same units.

Option 2: Modify daspect based on data range

Calculate the difference between the maximum and minimum values of your x and y limits, representing the range on each axis. Then, find the larger range and divide it by the smaller range to get the scaling factor. You can the modify then daspect like this:

daspect([scaling_factor 1 1]);

In your case, the following will give you square grids.

daspect([0.5599 1 1]);

You can also look into this link for more information on "daspect": https://www.mathworks.com/help/matlab/ref/daspect.html