来自 excel 文件的 MATLAB 持续时间（以毫秒为单位）

Question

我正在制作一个 Matlab 程序，该程序使用从打开文件对话框指定的 excel 文件中的数据。

[filename, pathname] = uigetfile({'*.xlsx','Excel Files(*.xlsx)'; '*.txt','Txt Files(*.txt)'}, 'Pick a file');
FilePath = append(pathname,filename);

opts = detectImportOptions(FilePath, "ReadVariableNames", false);
opts = setvartype(opts, 1, 'char');
data = readtable(FilePath, opts);

table = data(:,1);

现在代码是这样的。

enter image description here 之后，如您所见，日期保存为字符串。

但我真正想找到的是以毫秒为单位的时间差（持续时间）。

原始数据如下所示： enter image description here

A列和C列时间相同，所以我只想使用A列数据。

请帮助新手！我很感激！

Answer 1

问题已解决。

我分享我的代码来帮助遇到同样问题的其他人。

如果事情可以更简化，请离开 cmets。

1. 导入 Excel 文件进行分析

% Clean the memory and the code previously running
clc;
clear all;
close all;

% Sampling frequency of the acquired data
fs = 1e2; % Sampling Frequency - this can be found on LabView code.
Ts = 1/fs; % Sampling Interval

%Importing data from an excel file
[filename, pathname] = uigetfile({'*.xlsx','Excel Files(*.xlsx)'; '*.txt','Txt Files(*.txt)'}, 'Pick a file');
FilePath = append(pathname,filename);

[fPath ,fName, fExt] = fileparts(FilePath);

一个。从文件中查找“持续时间”

opts = spreadsheetImportOptions("NumVariables", 1);

% Specify sheet and range
opts.Sheet = "sheet1";
opts.DataRange = "A2";

% Specify column names and types
opts.VariableNames = "Time";
opts.VariableTypes = "datetime";

% Specify file level properties
opts.ImportErrorRule = "omitrow";
opts.MissingRule = "omitrow";

% Specify variable properties
opts = setvaropts(opts, "Time", "InputFormat", 'mm:ss.SSS');

tTable = readtable(FilePath, opts, "UseExcel", false);
tArray = table2array(tTable);

% Calculating time duration
tArray = tArray - tArray(1);

% Coverting to seconds
time = milliseconds(tArray)*1e-3;

% Clear temporary variables
clear opts;

% Discarding data if time difference is too big
ii = size(time(:,1));
k = 0;
disp('Now removing error data elements');

for i = 1:1:ii(1)-1
    a = time(i);
    b = time(i+1);
    if (b-a)>0.5 && k==0
        k=i+1;
        
        fprintf('Elements from %d seconds will be removed. (%dth element)\n', time(k),k);
        
        for j = ii(1):-1:k
            
            if rem(j,10)==0
                fprintf('%dth element is removed... \n',j);
            end
            
            time(j) = [];
        end
        
        break % Break the loop after removing error data
    end
end

disp('Time table is set.');

clearvars -except filename FilePath fs pathname time k ii Ts fName

Answer 2

我创建了一个类似的 excel 文件，我发现时间列被读取为一个字符。所以，我所做的是获取这些列的索引并将其转换为数据时间。之后，看起来它正在工作。希望这行得通。

% Define the excel file name (can be the path)
ExcelFile = 'demo_stackflow.xlsx';

% Get the options for that sheet and preserving the variable name
opts = detectImportOptions(ExcelFile,'Sheet','Sheet1',...
    "VariableNamingRule","preserve")
% Get the idx where the variable is a char (In this case col 1 and 3)
CharVars = opts.VariableNames(contains(opts.VariableTypes,'char'));
% Convert the char columns to datetime
opts = setvaropts(opts,CharVars,'Type',"datetime");
% Get the data
data = readtable(ExcelFile, opts)
% Print the 1st column to see if the data type of the column is
%  datetime
T = data(:,1)