为什么当 pandas 数据框中的数据类型是日期时间时，由于您的时间戳而无法使用 matplotlib.animation？

Question

我正在试验一维时间序列数据，并尝试通过动画在 GoogleColab 笔记本中我自己的数据上重现以下方法。

当 x 轴为

timestamp

时，将列列表值的数据类型作为 'datetime' 与数据帧一起传递时，我面临着从这篇文章中重新生成动画的问题！我认为即使当我尝试索引

timestamp

列并对使用

df.index

传递 x 轴值的绘图进行动画处理时，我也认为某处存在错误。

根据我的帖子中的学习，我在以下脚本中尝试失败的内容可在帖子末尾参考：

#-----------------------------------------------------------
# Libs
#-----------------------------------------------------------
import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation
from matplotlib.patches import Rectangle
from IPython.display import HTML

#-----------------------------------------------------------
# LOAD THE DATASET
#-----------------------------------------------------------

df = pd.read_csv('https://raw.githubusercontent.com/amcs1729/Predicting-cloud-CPU-usage-on-Azure-data/master/azure.csv')
df['timestamp'] =  pd.to_datetime(df['timestamp'])
df = df.rename(columns={'min cpu': 'min_cpu',
                        'max cpu': 'max_cpu',
                        'avg cpu': 'avg_cpu',})
df.head()


# Data preparation
# ==============================================================================
sliced_df = df[['timestamp', 'avg_cpu']]
# convert column to datetime object
#sliced_df['timestamp'] = pd.to_datetime(sliced_df['timestamp'], format='%Y-%m-%d %H:%M:%S')
#df = df.set_index('timestamp')


step_size = 4*287
data_train = sliced_df[:-step_size]
data_test  = sliced_df[-step_size:] #unseen


#-----------------------------------------------------------
# Animation
#-----------------------------------------------------------

# create plot
plt.style.use("ggplot")  # <-- set overall look
fig, ax = plt.subplots( figsize=(10,4))

# plot data
plt.plot(list(sliced_df['timestamp']), sliced_df['avg_cpu'], 'r-', linewidth=0.5,  label='data or y')

# make graph beautiful
plt.plot([], [], 'g-', label="Train", linewidth=8, alpha=0.3)
plt.plot([], [], 'b-', label="Test",  linewidth=8, alpha=0.3)

step_size = 287
selected_ticks = sliced_df['timestamp'][::step_size]
plt.xticks(selected_ticks, rotation=90)
#plt.gca().xaxis.set_major_formatter(mdates.DateFormatter('%Y-%m-%d %H:%M:%S'))


Y_LIM       = 2*10**8 #df[f'{name_columns}'].max()
TRAIN_WIDTH =  288*27
TEST_WIDTH  =  357*1
print(TRAIN_WIDTH)
print(TEST_WIDTH)

#plt.title(f'Data split:\n taraing-set {100*(len(data_train)/len(df)):.2f}% = {TRAIN_WIDTH/288:.2f} days and test-set {100*(len(data_test)/len(df)):.2f}% = {TEST_WIDTH/288:.f} days')
plt.title(f'Data split:\n taraing-set % =  days and test-set % = days')
plt.ylabel(f' usage',   fontsize=15)
plt.xlabel('Timestamp', fontsize=15)
plt.grid(True)
#plt.legend(loc="upper left")
plt.legend(bbox_to_anchor=(1.3,.9), loc="upper right")
fig.tight_layout(pad=1.2)


def init():
    rects = [Rectangle((0, 0)              , TRAIN_WIDTH, Y_LIM, alpha=0.3, facecolor='green'),
             Rectangle((0 + TRAIN_WIDTH, 0), TEST_WIDTH,  Y_LIM, alpha=0.3, facecolor='blue')]
    patches = []
    for rect in rects:
            patches.append(ax.add_patch(rect))
    return patches

def update(x_start):
    patches[0].xy = (x_start, 0)
    patches[1].xy = (x_start + TRAIN_WIDTH, 0)
    return patches


# create "Train" and "Test" areas
patches = init()

ani = FuncAnimation(
    fig,
    update,
    frames= np.linspace(0, 288, 80),  # all starting points
    interval=50,
    blit=True)


HTML(ani.to_html5_video())

---

我当前的输出：

---

预期的动画输出（但具有完整时间戳）：

---

参考：

• 如何随着时间的推移重现滚动窗口的动画？

Answer 1

问题是您想要绘制的绿色和蓝色补丁是相对于轴的，但您的图形数据具有它们自己的值。您需要将数据转换为 Matplotlib 绘图坐标。

您可以在下面找到一种非常幼稚和hacky的方法，但它应该可以让您了解如何处理它：

plt.style.use("ggplot")  # <-- set overall look
fig, ax = plt.subplots( figsize=(10,4))

# plot data
plt.plot(list(sliced_df['timestamp']), sliced_df['avg_cpu'], 'r-', linewidth=0.5,  label='data or y')

# translate data to graph coordinates
ax.margins(x=0, y=0)
x_min, x_max = ax.get_xlim()
y_min, y_max = ax.get_ylim()
ax.margins(x=0.05, y=0.05)
height = y_max-y_min

def init():
    rects = [Rectangle((x_min, y_min), 5,  height, alpha=0.3, facecolor='green'),
             Rectangle((x_min+5, y_min), 3,  height, alpha=0.3, facecolor='blue')]
    patches = []
    for rect in rects:
            patches.append(ax.add_patch(rect))
    return patches

def update(x_start):
    patches[0].xy = (x_start, y_min)
    patches[1].xy = (x_start + 5, y_min)
    return patches

patches = init()
ani = FuncAnimation(
    fig,
    update,
    frames= np.linspace(x_min, x_max-0.25*(x_max-x_min), 50),  # all starting points
    interval=150,
    blit=True)

HTML(ani.to_html5_video())