matplotlib x-axis勾选日期格式和位置

时间:2013-01-21 13:54:32

标签: matplotlib

我尝试使用matplotlib复制最初使用flotr2创建的pdf输出的绘制图形。我必须说flotr更容易使用......但除此之外 - 我目前坚持尝试将x轴上的日期/时间格式化为所需的格式,即小时:分钟,间隔为每2小时,如果期间如果周期超过1天且间隔为一天,则x轴上的小于一天和年 - 月 - 日格式。

我已经阅读了大量的例子并尝试复制它们,但结果仍然是相同的,即小时:分钟:根据周期的长短,间隔为1到3小时的秒。 enter image description here

我的代码:

colorMap = {
        'speed': '#3388ff',
        'fuel': '#ffaa33',
        'din1': '#3bb200',
        'din2': '#ff3333',
        'satellites': '#bfbfff'
}

otherColors = ['#00A8F0','#C0D800','#CB4B4B','#4DA74D','#9440ED','#800080','#737CA1','#E4317F','#7D0541','#4EE2EC','#6698FF','#437C17','#7FE817','#FBB117']

plotMap = {}

import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import matplotlib.dates as dates
fig = plt.figure(figsize=(22, 5), dpi = 300, edgecolor='k')
ax1 = fig.add_subplot(111)

realdata = data['data']
keys = realdata.keys()
if 'speed' in keys:
    speed_index = keys.index('speed')
    keys.pop(speed_index)
    keys.insert(0, 'speed')

i = 0
for key in keys:
    if key not in colorMap.keys():
        color = otherColors[i]
        otherColors.pop(i)
        colorMap[key] = color
        i += 1

label = u'%s' % realdata[keys[0]]['name']
ax1.set_ylabel(label)

plotMap[keys[0]] = {}
plotMap[keys[0]]['label'] = label

first_dates = [ r[0] for r in realdata[keys[0]]['data']]

date_range = first_dates[-1] - first_dates[0]


ax1.xaxis.reset_ticks()

if date_range > datetime.timedelta(days = 1):
    ax1.xaxis.set_major_locator(dates.WeekdayLocator(byweekday = 1, interval=1))
    ax1.xaxis.set_major_formatter(dates.DateFormatter('%Y-%m-%d'))
else:
    ax1.xaxis.set_major_locator(dates.HourLocator(byhour=range(24), interval=2))
    ax1.xaxis.set_major_formatter(dates.DateFormatter('%H:%M'))

ax1.xaxis.grid(True)

plotMap[keys[0]]['plot'] = ax1.plot_date(
                                dates.date2num(first_dates), 
                                [r[1] for r in realdata[keys[0]]['data']], colorMap[keys[0]], xdate=True)

if len(keys) > 1:
    first = True
    for key in keys[1:]:
        if first:
            ax2 = ax1.twinx()
            ax2.set_ylabel(u'%s' % realdata[key]['name'])
            first = False
        plotMap[key] = {}
        plotMap[key]['label'] = u'%s' % realdata[key]['name']
        plotMap[key]['plot'] = ax2.plot_date(
                                    dates.date2num([ r[0] for r in realdata[key]['data']]), 
                                    [r[1] for r in realdata[key]['data']], colorMap[key], xdate=True)


plt.legend([value['plot'] for key, value in plotMap.iteritems()], [value['label'] for key, value in plotMap.iteritems()], loc = 2)

plt.savefig(path +"node.png", dpi = 300, bbox_inches='tight')
有人可能会指出为什么我没有得到理想的结果吗?

EDIT1:

我在绘图后移动了格式化块,现在看起来效果会更好。但它们现在仍然是理想的结果。如果周期小于一天,那么我会在每2个小时(间隔= 2)之后得到一个滴答,但我希望我能在偶数小时得到那些滴答而不是不均匀的小时。这可能吗?

if date_range > datetime.timedelta(days = 1):
    xax.set_major_locator(dates.DayLocator(bymonthday=range(1,32), interval=1))
    xax.set_major_formatter(dates.DateFormatter('%Y-%m-%d'))
else:
    xax.set_major_locator(dates.HourLocator(byhour=range(24), interval=2))
    xax.set_major_formatter(dates.DateFormatter('%H:%M'))

EDIT2: 这似乎给了我想要的东西:

if date_range > datetime.timedelta(days = 1):
    xax.set_major_locator(dates.DayLocator(bymonthday=range(1,32), interval=1))
    xax.set_major_formatter(dates.DateFormatter('%Y-%m-%d'))
else:
    xax.set_major_locator(dates.HourLocator(byhour=range(0,24,2)))
    xax.set_major_formatter(dates.DateFormatter('%H:%M'))

艾伦

2 个答案:

答案 0 :(得分:9)

你这样做比你需要的更难。 matplotlib可以直接绘制datetime个对象。我怀疑你的问题是你正在设置定位器,然后绘图,并且绘图正在用默认的自动版本替换你的定位器/格式化程序。尝试将关于定位器的逻辑块移动到下面绘图循环。

我认为这可以取代你公平的代码:

d = datetime.timedelta(minutes=2)
now =  datetime.datetime.now()
times = [now + d * j for j in range(500)]
ax = plt.gca() # get the current axes
ax.plot(times, range(500))

xax = ax.get_xaxis() # get the x-axis
adf = xax.get_major_formatter() # the the auto-formatter


adf.scaled[1./24] = '%H:%M'  # set the < 1d scale to H:M
adf.scaled[1.0] = '%Y-%m-%d' # set the > 1d < 1m scale to Y-m-d
adf.scaled[30.] = '%Y-%m' # set the > 1m < 1Y scale to Y-m
adf.scaled[365.] = '%Y' # set the > 1y scale to Y

plt.draw()

doc for AutoDateFormatter

答案 1 :(得分:8)

我通过这样做实现了我想要的目标:

if date_range > datetime.timedelta(days = 1):
    xax.set_major_locator(dates.DayLocator(bymonthday=range(1,32), interval=1))
    xax.set_major_formatter(dates.DateFormatter('%Y-%m-%d'))
else:
    xax.set_major_locator(dates.HourLocator(byhour=range(0,24,2)))
    xax.set_major_formatter(dates.DateFormatter('%H:%M'))