Data filtering of MATLAB

Matlab Powerful , Here are some data filtering methods , At least let it reach Excel The degree of data filtering

One 、 Take some rows or columns from the multidimensional array and combine them into a new array

Examples are as follows ： Take some columns to form a new array

newdata=olddata(:,[1 5 8 2 6]);

Two 、 Filter a row or column of a multidimensional array according to a certain condition , Expand to other rows or columns at the same time

olddata Is a multi row and multi column array .

newdata=olddata(olddata(:,1)==value,:);

3、 ... and 、 Screening method

3.1 Find all elements in a certain range

pf=olddata(olddata(:,1)>=value1&olddata(:,1)<=value2);
tempnum=find(pf<=value1&pf>=value2);

3.2

Four 、 String splicing

newstr=strcat(oldstr,'new text');

Line feed operation ： Use braces {} Or use newline As a line break

str=[{
    'ueifkdu';'877'}];

chr = 'Whose woods these are I think I know.';
chr = [chr newline 'His house is in the village though']

5、 ... and 、 Import csv file

csvread function ...
Parameters 1： File path ;
Parameters 2： Number of lines to start （ The default from the 0 OK, let's start ）;
Parameters 3： Number of columns to start （ The default from the 0 Column start ）.

data=csvread('121.csv',1,1);

It could be wrong ： The first line of Chinese is garbled , Do not read from 0 Just start the line .

6、 ... and 、figure Set up

xlabel('MHz');% Set up X Axis labels 
ylabel('Angle');% Set up y Axis labels 
title('Usefull');% Set title 
xlim([0 6000]);% Set up X Axis display range 
ylim([0 180]);% Set up Y Axis display range 
set(gcf,'position',[50,70,1400,700]);% Set up figure Location and size 
text(xloc,yloc,showstr);% Display text at coordinate points 

yRange=ylim;% Get current figure Of y Axis display range 

7、 ... and 、 Save pictures and csv data

% Whether the save path exists , There is no new building 
if ~isfolder(savepath)
	mkdir(savepath);
end

saveas(2,strcat(savepath,'001.jpg');% preservation figure2
saveas(1,strcat(savepath,'002.jpg');% preservation figure1

savepath=strcat(savepath,'.csv');
csvwrite(savepath,Data);