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
...
例如输出由第二组计数：
2001-03-23 05:01:33.000,3
2001-03-23 05:01:34.000,1
...
Answer 1:
这里有一种方法：
% 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]
我们没有转换成串行日期数字，我们也可以做如下：
% 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)];
文章来源: Count entries per time interval in MATLAB
