x轴上带有时间戳的 pandas 图-刻度单位?

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问题描述

我有一个带有日期时间值的熊猫数据框:

I have a pandas data frame with datetime values:

    Date/Time           Event Value
0   2018-11-15 17:17:49 62
1   2018-11-15 17:27:50 63
2   2018-11-15 17:37:50 64
3   2018-11-15 17:42:49 65
4   2018-11-15 18:17:49 64
5   2018-11-15 19:27:48 65
6   2018-11-15 19:37:48 66
7   2018-11-15 19:47:49 67
8   2018-11-15 19:57:49 68
9   2018-11-15 20:12:49 69

print (tmp.dtypes)

Date/Time      datetime64[ns]
Event Value             int64

按如下所示进行绘制:

fig, ax1 = plt.subplots(1,1,figsize=(8,4))
tmp.plot(x='Date/Time',y='Event Value', legend=None, ax=ax1)

x轴已使用适当的日期和时间进行了格式化(并且可以使用set_major_formatter进行进一步格式化).

The x-axis has been formatted with appropriate dates and times (and can be further formatted using set_major_formatter).

现在，我想在图表上绘制一个矩形，以突出显示特定时间.为此，我需要知道x位置.

Now I want to draw a rectangle on the chart, to highlight a particular time. To do that I need to know the x-positions.

print([x for x in ax1.get_xticks()])

[737013.7291666666, 737013.75, 737013.7708333334, 737013.7916666666, 737013.8125, 737013.8333333334]

这些确实是x值，即，如果我将它们用作矩形的原点，则会按预期绘制.

These are indeed the x-values, i.e. if I use them as origins for the rectangle it plots as expected.

rect = patches.Rectangle((737013.75,55),.01,100)
ax1.add_patch(rect)

我不知道这些数字是从哪里来的.它们不是时代值，尽管看起来有点像它们("737013.75"对应于"1970-01-09 07:43:33"，对我而言没有任何意义).

I don't understand where these numbers come from. They're not epoch values, though they look a little bit like them ('737013.75' corresponds to '1970-01-09 07:43:33', which doesn't mean anything to me).

如何从数据框中的日期/时间值获取图表上的x位置?

How can I get the x-position on the chart from a Date/Time value in my dataframe?

Dates

x轴上带有时间戳的 pandas 图-刻度单位?

问题描述

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