生成一致的datenums数组 [英] Generating consistent arrays of datenums

问题描述

每当需要绘制数据与时间的关系时，都会生成相应的datenums数组，这样我就可以通过调用datetick来可视化plot上的时间轴.

Whenever I need to plot data vs time I generate the corresponding array of datenums so I can visualize a timeline on the plot by calling datetick.

假设我需要所有在h_1和h_2小时之间有1分钟间隔的datenum.这就是我如何生成我的datenums vd数组:

Let's suppose I need all the datenums with a 1 minute interval between hours h_1 and h_2. This is how would I generate my array of datenums vd:

h_1 = [01 00]; % 01:00 AM
h_2 = [17 00]; % 17:00 PM

HH_1 = h_1(1); % Hour digits of h_1
MM_1 = h_1(2); % Minute digits of h_1

HH_2 = h_2(1); % Hour digits of h_2
MM_2 = h_2(2); % Minute digits of h_2


% Vector of 01:00 - 17:30 with 1 minute increments (24 hours a day, 1440 minutes a day)

vd = HH_1/24+MM_1/1440:1/1440:HH_2/24+MM_2/1440;

我阅读了这个答案.

另一方面，每当我希望生成单个datenum时，我都会使用datenum函数，如下所示:

On the other hand, whenever I wish to generate a single datenum, I use the datenum function like this:

d = datenum('14:20','HH:MM');

由于时间间隔01:00-17:30之间包含14:20，因此它的datenum也应该是如此！不幸的是，这不能按预期方式工作，因为分配给d的数字与vd中包含的值根本不同.我想我可能会遗漏一些东西，可能与设置参考日期或类似日期有关.

Since 14:20 is comprised between the interval 01:00 - 17:30, its datenum should be too! Unfortunately this is not working as expected, since the number assigned to d is radically different to those values contained in vd. I think I might be missing something, probably something to do with setting up a reference date or similar.

那么一致地生成datenum的合适方法是什么?

So what would be the appropriate way to generate datenums consistently?

推荐答案

原因是datenum函数为您提供了从0000年1月0日开始的天数. 所以在打电话时

The reason is that the datenum function gives you a number of days from January 0, 0000. So when calling

d = datenum('14:20','HH:MM');

您得到的数字约为735965，而vd数组中的数字介于0和1之间.为了构造1月0日，0000年至今的日期，您可以编写

you get a number about 735965, while the numbers in your vd array are between 0 and 1. In order to substruct the days between January 0, 0000 and today you can write

d = datenum('14:20','HH:MM') - datenum('00:00','HH:MM');

然后您的代码将如下所示

Then your code will look like

h_1 = [01 00]; % 01:00 AM
h_2 = [17 00]; % 17:00 PM

HH_1 = h_1(1); % Hour digits of h_1
MM_1 = h_1(2); % Minute digits of h_1

HH_2 = h_2(1); % Hour digits of h_2
MM_2 = h_2(2); % Minute digits of h_2

vd = HH_1/24 + MM_1/1440   :  1/1440  :  HH_2/24+MM_2/1440;

d = datenum('14:20','HH:MM') - datenum('00:00','HH:MM');

display(d);
display(vd(801));

结果:

d = 0.5972
ans = 0.5972

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