使用 matplotlib 在轴标签中创建带有日期和时间的图形 [英] Creating graph with date and time in axis labels with matplotlib
问题描述
我的数据在以下结构的数组中,
I have my data in an array of the following structure,
[[1293606162197, 0, 0],
[1293605477994, 63, 0],
[1293605478057, 0, 0],
[1293605478072, 2735, 1249],
[1293606162213, 0, 0],
[1293606162229, 0, 0]]
第一列是纪元时间(以ms
为单位),第二列是y1
,第三列是y2
.我需要在 x 轴上绘制时间图,在左右 y 轴上绘制 y1
和 y2
.
The first column is epoch time (in ms
), second is y1
and third is y2
. I need a plot with the time on the x-axis, and y1
and y2
on left and right y-axes.
我一直在浏览文档,但找不到任何方法让我的 x 轴刻度同时显示日期和时间,例如28/12 16:48",即日期/月份小时:分钟"".所有帮助我的文档都是单独显示日期,但这不是我想要的.任何帮助将不胜感激.
I have been scouring through the documentation but couldn't find any way to get my x-axis ticks to display both date and time, like "28/12 16:48", i.e., "date/month hour:min". All the documentation helps me with is to display dates alone, but that is not what I want. Any help would be appreciated on this.
而且,如果看起来像,这不是家庭作业.它实际上是对我之前的问题的跟进,读取和绘制数据读取来自大文件.
And, if it may seem like, this is not homework. It is actually a follow up to my previous question, Reading and graphing data read from huge files.
推荐答案
我希望这会有所帮助.我一直很难处理 matplotlib 的日期.Matplotlib 需要 float 格式,这是自纪元以来的几天.辅助函数 num2date
和 date2num
以及 Python 内置的 datetime
可用于相互转换.格式化业务是从 this 示例中提取的.您可以使用 set_major_formatter
将任何图上的轴更改为日期轴.
I hope this helps. I've always had a hard time with matplotlib's dates. Matplotlib requires a float format which is days since epoch. The helper functions num2date
and date2num
along with python builtin datetime
can be used to convert to/from. The formatting business was lifted from this example. You can change an axis on any plot to a date axis using set_major_formatter
.
import numpy as np
from matplotlib import pyplot as plt
from matplotlib import dates
import datetime
a = np.array([
[1293605162197, 0, 0],
[1293605477994, 63, 0],
[1293605478057, 0, 0],
[1293605478072, 2735, 1249],
[1293606162213, 0, 0],
[1293606162229, 0, 0]])
d = a[:,0]
y1 = a[:,1]
y2 = a[:,2]
# convert epoch to matplotlib float format
s = d/1000
ms = d-1000*s # not needed?
dts = map(datetime.datetime.fromtimestamp, s)
fds = dates.date2num(dts) # converted
# matplotlib date format object
hfmt = dates.DateFormatter('%m/%d %H:%M')
fig = plt.figure()
ax = fig.add_subplot(111)
ax.vlines(fds, y2, y1)
ax.xaxis.set_major_locator(dates.MinuteLocator())
ax.xaxis.set_major_formatter(hfmt)
ax.set_ylim(bottom = 0)
plt.xticks(rotation='vertical')
plt.subplots_adjust(bottom=.3)
plt.show()
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