如何使 hist2d xaxis 刻度为日期时间格式？

Question

我想将 unixtime 转换为 datetime 格式以使用 hist2d 显示以下数据。但是，每次我将 unixtime 转换为 datetime

我得到了"TypeError: ufunc 'isfinite' not supported for the input types, and the inputs could not be safely coerced to any supported types according to the casting rule ''safe''"

我要绘制的数据：

如果我将 unixtime 设置为 xsticks，这就是我绘制的内容：

剧情应该是这样的

import numpy as np
import matplotlib.pyplot as plt
from matplotlib.colors import LinearSegmentedColormap

# example data
x = df_1['unix_time']
y = df_1['bid_ask_spread']

# Set up x_ticks
time_frame = np.linspace(1575254259187, 1575513459187, 73)
x_ticks = []
for i in time_frame:
    x_ticks.append(to_datetime(i))

# make a custom colormap with transparency
ncolors = 256
color_array = plt.get_cmap('YlOrRd')(range(ncolors))
color_array[:, -1] = np.linspace(0, 1, ncolors)
cmap = LinearSegmentedColormap.from_list(name='YlOrRd_alpha', colors=color_array)

fig, ax1 = plt.subplots(1, 1, figsize=(16,9), dpi=80)

ax1.hist2d(x, y, bins=[71, 81], cmap=cmap, edgecolor='white')

# ax1.set_xticks(x_ticks[::5])
ax1.set_ylim(bottom=0)

plt.show()

Answer 1

我的感觉是，您需要使用 numpy.histogram2d 来计算直方图，然后将边缘转换为 datetime 格式，最后绘制直方图与转换后的坐标。

# Test data
N = 2*24*60
df = pd.DataFrame({'unix_time':pd.date_range(start='2018-02-01', freq='1min', periods=N).strftime('%s').astype(int),
                   'value':np.random.normal(size=(N,))})

# compute the 2D histogram using numpy
H,xedges,yedges = np.histogram2d(df['unix_time'], df['value'], bins=[24,10])
# convert the x-edges into datetime format
to_datetime = np.vectorize(datetime.datetime.fromtimestamp)
xedges_datetime = to_datetime(xedges)

# plot the two cases side by side
fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(8,3))
ax1.hist2d(df['unix_time'],df['value'], bins=[24,10])
ax1.set_title('unix_time')

ax2.pcolor(xedges_datetime, yedges, H.T)
ax2.set_title('datetime')
# pretty up the xaxis labels
ax2.xaxis.set_major_locator(loc)
ax2.xaxis.set_major_formatter(fmt)


fig.autofmt_xdate()
fig.tight_layout()

如何使 hist2d xaxis 刻度为日期时间格式？

How to make hist2d xaxis ticks as datetime format?

python

datetime

matplotlib

histogram