如何在特定时间间隔内对日期进行分组

本文介绍了如何在特定时间间隔内对日期进行分组的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个日期数组，我想舍弃在特定时间间隔(例如5分钟)内没有至少另一个日期的任何日期.我需要找到一种明智的方式来实现此目标，因为循环会永久占用更大的数据集.

I have an array of dates and i would like to discard any dates that don't have at least one another date in a specific time interval, for example 5 minutes. I need to find a smart way to do it, as loops take forever with a larger dataset.

输入数据:

2009 07 07 16:01:30

2009 07 07 16:01:30

2009 07 07 16:04:06

2009 07 07 16:04:06

2009 07 07 16:05:00

2009 07 07 16:05:00

2009 07 07 16:12:00

2009 07 07 16:12:00

2009 07 07 16:19:43

2009 07 07 16:19:43

2009 07 07 16:24:00

2009 07 07 16:24:00

结果:

2009 07 07 16:01:30

2009 07 07 16:01:30

2009 07 07 16:04:06

2009 07 07 16:04:06

2009 07 07 16:05:00

2009 07 07 16:05:00

2009 07 07 16:19:43

2009 07 07 16:19:43

2009 07 07 16:24:00

2009 07 07 16:24:00

值2009 07 07 16:12:00被丢弃，因为它与其他任何时间戳都相距5分钟以上.

The value 2009 07 07 16:12:00 was discarded because it was more than 5 minutes away from any other timestamp.

谢谢， 克里斯蒂

次要问题:

Dan和nkjt都提出了一个可行的实现，谢谢！如果日期是2个组的一部分，该怎么办:A或B，我想查找A组中是否存在一个日期，该日期在B组中具有一个相隔数秒/分钟的日期?如果不是的话，只需从A组中删除日期即可.

Both Dan and nkjt suggested an implementation that worked, thanks! What if the dates are part of 2 groups: A or B and i want to find if there exist a date from group A that has a corresponding date in group B that is within a number of seconds/minutes apart? if not just remove the date from group A..

推荐答案

您可以使用diff.您需要使用datenum将数据转换为值向量.在MATLAB datenums中，"1"是一天，因此您可以按照时间单位除以一天中的日期数来定义datenum步骤:

You can use diff. You'll need to use datenum to convert your data into a vector of values. In MATLAB datenums, "1" is a single day, so you can define a datenum step in terms of a time unit divided by the number of those in a day:

s = num_mins/(24*60);

这是diff的窍门:

x = datenum(mydata); s = num_mins/(24*60); % for increasing times we shouldn't need the `abs` but to be safe d = abs(diff(x)); q = [d (s+1)]>s&[(s+1) d]>s;

(您可以使用datestr进行转换，或将q应用于原始数据)

(You can use datestr to convert back, or apply q to the original data)

工作方式:

diff的输出比原始输出短一个-它只是相邻值之间的差.我们需要它具有方向性-对照前后的值来检查每个值.

The output of diff is one shorter than the original - it's just the difference between neighbouring values. We need it to be directional - to check each value against the one that comes before and after.

[d (s+1)]>s使向量的长度与原始长度相同，并检查差值是否大于s.因为我们将最后一个值设置为s + 1，所以最终值将始终返回true.这是对一个值和它后面的值之间是否存在间隙的检查(因此对于最终值，它始终为真).

[d (s+1)]>s makes a vector the same length as the original, and checks if the difference values are larger than s. Because we set the last value to be s+1, the final value will always return true. This is a check to whether there's a gap between a value and the one following it (so for the final value this is always true).

[(s+1) d]>s的功能相同，但另一面.同样，我们将一个值设置为大于s，这是第一个值，因此始终为真.

[(s+1) d]>s does the same but on the other side. Again, we are setting one value, this time the first, to be larger than s so it's always true.

将这些结合起来可以得出两边相差超过5分钟的点(或者对于端点而言，相差超过5分钟).

Combining these gives us the points where the difference is more than five minutes on either side (or for the end points, on one side).