matlab - 在 MATLAB 中计算每个时间间隔的条目

Question

我想计算每个时间间隔的条目。

源数据集 nx2

2001-03-23 05:01:33.347,55
2001-03-23 05:01:33.603,62
2001-03-23 05:01:33.977,32
2001-03-23 05:01:34.126,30
...

按秒分组计数的示例输出：

2001-03-23 05:01:33.000,3
2001-03-23 05:01:34.000,1
...

Answer 1

这是一种方法：

% dataset
data = {
  '2001-03-23 05:01:33.347', 55 ;
  '2001-03-23 05:01:33.603', 62 ;
  '2001-03-23 05:01:33.977', 32 ;
  '2001-03-23 05:01:34.126', 30 ;
};

% convert to serial date (ignoring the seconds fraction part)
dt = datenum(data(:,1), 'yyyy-mm-dd HH:MM:SS');

% convert to group indices
[dt,~,ind] = unique(dt);

% count occurences per group
counts = accumarray(ind, cell2mat(data(:,2)), [], @numel);

% construct resulting dataset
X = [cellstr(datestr(dt, 'yyyy-mm-dd HH:MM:SS.FFF')) num2cell(counts)];

结果：

>> X
X = 
    '2001-03-23 05:01:33.000'    [3]
    '2001-03-23 05:01:34.000'    [1]

---

我们不必转换为序列号，我们还可以执行以下操作：

% treat column as a char matrix
dt = char(data(:,1));
dt = dt(:,1:end-4);   % remove fractions of seconds

% unique entries
[dt,~,ind] = unique(dt, 'rows');

% counting
counts = accumarray(ind, cell2mat(data(:,2)), [], @numel);

% result
X = [cellstr(strcat(dt,'.000')) num2cell(counts)];