How select/crop geographic region on the basis of lat/lon values?

Question

Kamran Afroz 2023-7-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1992973-how-select-crop-geographic-region-on-the-basis-of-lat-lon-values

编辑： Pranavkumar Mallela 2023-7-27

I want to select/crop region on the basis of lat/lon.

I have geographical data with dimensions of lat,lon and time from which I want to crop a region using four lat/lon(e.g. LAT: 13,18; LON: 73,76) points like a rectangle.

I have attached my sample data for reference.

Can anyone help me with this problem?

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Pranavkumar Mallela 2023-7-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1992973-how-select-crop-geographic-region-on-the-basis-of-lat-lon-values#answer_1268918

编辑：Pranavkumar Mallela 2023-7-27

在 MATLAB Online 中打开

Hi,

As per my understanding, you are trying to crop a region that is part of the sample data, which includes the 'rf' value over a 100x100 area and 48 time instances.

First use 'ncread' to read the 'rf' variable from the above attached file in the following way:

rf = ncread("test.nc", 'rf');

The variable 'rf' is a 100x100x48 double matrix. To crop a certain geographical region at a given time 't', you can use the following code:

cropped_region = rf(13:18, 73:76, t); % at a given time 't'

For more information regarding selection of data from a matrix, you can refer the following documentation: https://www.mathworks.com/help/matlab/math/array-indexing.html

Hope this helps! Thanks!

3 个评论
显示 1更早的评论隐藏 1更早的评论

Pranavkumar Mallela 2023-7-7

编辑：Pranavkumar Mallela 2023-7-27

在 MATLAB Online 中打开

Hey, thanks for clarifying that.

You can utilize the 'find' function to find the indices of the required latitude and longitude ranges.

The code is as follows:

lat = [1 2 3 4 5 6 7 8 9 10]; % assume this is your latitude data
lon = [1 2 3 4 5 6 7 8 9 10]; % assume this is your longitude data
% Set the required limits here
req_lat_ll = 13; req_lat_ul = 18;
req_lon_ll = 73; req_lon_ul = 76;
lat_ll  = find(lat <= req_lat_ll ,1,'last'); % ll = lower limit
lat_ul = find(lat >= req_lat_ul,1,'first'); % ul = upper limit
lon_ll  = find(lon <= req_lon_ll ,1,'last');
lon_ul = find(lon >= req_lon_ul,1,'first');
cropped_region = rf(lat_ll:lat_ul, lon_ll:lon_ul, t); % at a given time 't'