matplotlib 如何指定时间定位器的开始计时时间戳? [英] matplotlib how to specify time locator's start-ticking timestamp?

问题描述

我想要的很简单，我只想让定位器刻度在指定的时间戳记开始:
伪代码:locator.set_start_ticking_at( datetime_dummy )
到目前为止，我没有找到任何东西.

这是这个问题的代码部分:

 axes[0].set_xlim(datetime_dummy) # datetime_dummy = '2015-12-25 05:34:00'将matplotlib.dates导入为matdatesseclocator = matdates.SecondLocator(间隔=20)minlocator = matdates.MinuteLocator(时间间隔= 1)hourlocator = matdates.HourLocator(interval = 12)seclocator.MAXTICKS = 40000minlocator.MAXTICKS = 40000hourlocator.MAXTICKS = 40000MajorFmt = matdates.DateFormatter('%Y-%m-%d, %H:%M:%S')minorFmt = matdates.DateFormatter('％H:％M:％S')axes [0] .xaxis.set_major_locator(minlocator)axes [0] .xaxis.set_major_formatter(majorFmt)plt.setp(axes [0] .xaxis.get_majorticklabels()，rotation = 90)轴[0].xaxis.set_minor_locator(seclocator)轴[0].xaxis.set_minor_formatter(minorFmt)plt.setp(axes [0] .xaxis.get_minorticklabels()，rotation = 90)# 其他代码#将无花果另存为图片

上面代码的x轴刻度将使我明白

如何告诉次要定位器与主要定位器对齐?
如何告诉定位器从哪个时间戳开始计时?

我尝试过的方法:
set_xlim 不能解决问题
seclocator.tick_values(datetime_dummy, datetime_dummy1) 什么都不做

解决方案

不要使用 interval 关键字参数，而是使用

All I want is quite straight forward, I just want the locator ticks to start at a specified timestamp:
peudo code: locator.set_start_ticking_at( datetime_dummy )
I have no luck finding anything so far.

Here is the portion of the code for this question:

    axes[0].set_xlim(datetime_dummy) # datetime_dummy = '2015-12-25 05:34:00'
    import matplotlib.dates as matdates
    seclocator = matdates.SecondLocator(interval=20) 
    minlocator = matdates.MinuteLocator(interval=1) 
    hourlocator = matdates.HourLocator(interval=12)

    seclocator.MAXTICKS  = 40000
    minlocator.MAXTICKS  = 40000
    hourlocator.MAXTICKS  = 40000

    majorFmt = matdates.DateFormatter('%Y-%m-%d, %H:%M:%S')  
    minorFmt = matdates.DateFormatter('%H:%M:%S')  

    axes[0].xaxis.set_major_locator(minlocator)
    axes[0].xaxis.set_major_formatter(majorFmt)
    plt.setp(axes[0].xaxis.get_majorticklabels(), rotation=90 )

    axes[0].xaxis.set_minor_locator(seclocator)
    axes[0].xaxis.set_minor_formatter(minorFmt)
    plt.setp(axes[0].xaxis.get_minorticklabels(), rotation=90 )

    # other codes
    # save fig as a picture

The x axis ticks of above code will get me:

How do I tell the minor locator to align with the major locator?
How do I tell the locators which timestamp to start ticking at?

what I have tried:
set_xlim doesn't do the trick
seclocator.tick_values(datetime_dummy, datetime_dummy1) doesn't do anything

解决方案

Instead of using the interval keyword parameter, use bysecond and byminute to specify exactly which seconds and minutes you with to mark. The bysecond and byminute parameters are used to construct a dateutil rrule. The rrule generates datetimes which match certain specified patterns (or, one might say, "rules").

For example, bysecond=[20, 40] limits the datetimes to those whose seconds equal 20 or 40. Thus, below, the minor tick marks only appear for datetimes whose soconds equal 20 or 40.

import numpy as np
import matplotlib.pyplot as plt
import matplotlib.dates as matdates

N = 100

fig, ax = plt.subplots()
x = np.arange(N).astype('<i8').view('M8[s]').tolist()
y = (np.random.random(N)-0.5).cumsum()
ax.plot(x, y)


seclocator = matdates.SecondLocator(bysecond=[20, 40]) 
minlocator = matdates.MinuteLocator(byminute=range(60))  # range(60) is the default

seclocator.MAXTICKS  = 40000
minlocator.MAXTICKS  = 40000

majorFmt = matdates.DateFormatter('%Y-%m-%d, %H:%M:%S')  
minorFmt = matdates.DateFormatter('%H:%M:%S')  

ax.xaxis.set_major_locator(minlocator)
ax.xaxis.set_major_formatter(majorFmt)
plt.setp(ax.xaxis.get_majorticklabels(), rotation=90)

ax.xaxis.set_minor_locator(seclocator)
ax.xaxis.set_minor_formatter(minorFmt)
plt.setp(ax.xaxis.get_minorticklabels(), rotation=90)

plt.subplots_adjust(bottom=0.5)
plt.show()

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