(2016a) How to plot datetime versus numbers? Error: "Data inputs must match the axis configuration. A numeric axis must have numeric data inputs or data inputs which can be converted to double."

2020 7 10
2 个回答
回答已采纳
更新时间：2020 7 10
14 次查看（30 天）

0 个投票

I'm using Matlab 2016a and I am relatively new to Matlab. I have imported data from a large external file. The first column is datetime in the following format:
2015-07-01 01:00:00
The other columns are all numbers. E.g.,
1100.0
I want to plot the datetime data as X and numbers as Y. I have tried the following, where DT_1 is the column of imported datetime data and n_raw is a column of numbers:
DT_1_test = datetime(DT_1, 'InputFormat', 'yyyy-MM-dd HH:mm:ss')
t = datetime(DT_1_test);
DateNumber = datenum(t)
plot(DateNumber, n_raw);
There are two problems.
  1. My screen output for datetime is in the wrong format. Example: 10-Jul-2019 23:00:00
  2. Also, I get this error: "Data inputs must match the axis configuration. A numeric axis must have numeric data inputs or data inputs which can be converted to double."
I would be very grateful for any help. I have not been able to get past it all day. Thank you.

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Jane Fowler
Jane Fowler 2020-7-10
Update
I tried the following and it solved part of my problem:
DT_1_test = datetime(DT_1, 'InputFormat', 'yyyy-MM-dd HH:mm:ss')
t = datetime(DT_1_test);
plot(datenum(t), n_raw);
It gave me a plot!
  1. But I still have the problem that the date is not in the right format. My screen output shows the dates as "10-Jul-2019 23:00:00" and NOT as "yyyy-MM-dd HH:mm:ss" (what I need).
  2. Also, the X axis values are appearing as numbers, not dates.

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Steven Lord
Steven Lord 2020-7-10

0 个投票

For your first question, you've specified the format that datetime should use to interpret the representation of the time that you passed in, but you didn't specify the format in which the created datetime should be displayed. To do that, specify the 'Format' name-value pair argument (just like you specified 'InputFormat', with the desired format as the value in that pair.
dt1 = datetime('now')
dt2 = datetime('now', 'Format', 'yyyy-MM-dd HH:mm:ss')
For your second question, if you've previously plotted a line whose x data is numeric, you can't add another line to that same axes whose x data is a datetime.
x = 0:360;
y = sind(x);
plot(x, y)
hold on
x2 = datetime('today') + days(x);
plot(x2, y) % won't work
For this particular case, there's a reasonably intuitive mapping between x and x2. But in general there wouldn't be. In those cases answering a question like "Does x = 28 correspond to a week from now?" to line up the two plots could be difficult.

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Jane Fowler
Jane Fowler 2020-7-10
Thank you very much, Steven.
First, I am very happy to find that this worked to format the screen output correctly:
DT_1_test = datetime(DT_1, 'InputFormat', 'yyyy-MM-dd HH:mm:ss', 'Format', 'yyyy-MM-dd HH:mm:ss')
Regarding your second point, I haven't previously plotted any x data that are numeric, so I'll keep working on this issue.
Thanks again very much for your help with that first point!

请先登录，再进行评论。

更多回答（1 个）

Jane Fowler
Jane Fowler 2020-7-10

1 个投票

OK, finally figured it out. I'll post my solution here because there are bound to be other newbies like me who have the same problem.
1. Steven solved my first problem, the formatting of the on-screen datetime and therefore I'll mark his answer correct.
2. I came across a forum post elsewhere where someone suggested using "datetick" to convert the x axis numbers to dates (see below).
DT_1_test = datetime(DT_1, 'InputFormat', 'yyyy-MM-dd HH:mm:ss', 'Format', 'yyyy-MM-dd HH:mm:ss')
t = datetime(DT_1_test);
plot(datenum(t), n_raw);
datetick('x', 'yyyy-mm-dd')

类别

在 帮助中心 和 File Exchange 中查找有关 Dates and Time 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by