我正在用Flask制作一个网络应用,该应用在一个网页上显示不同的pyplot图表。以下是我用来创建不同绘图的代码,然后将它们作为以base64编码的png图像返回。
import pandas as pd
import numpy as np
from sklearn.linear_model import LinearRegression
from sklearn.metrics import mean_squared_error
import matplotlib.pyplot as plt
import io
import base64
def simple_plot():
img = io.BytesIO()
np.random.seed(196801)
x = np.random.rand(50)
y = np.random.rand(50)
plt.plot(x, y)
plt.savefig(img, format='png')
img.seek(0)
lp = base64.b64encode(img.getvalue()).decode()
plt.close()
return lp
def scatter_plot():
img = io.BytesIO()
np.random.seed(19680801)
x = np.random.rand(30)
y = np.random.rand(30)
colors = np.random.rand(30)
area = np.pi * (15 * np.random.rand(30)) ** 2
plt.scatter(x, y, s=area, c=colors, alpha=0.5)
plt.savefig(img, format='png')
img.seek(0)
sp = base64.b64encode(img.getvalue()).decode()
plt.close()
return sp
def linear_reg_plot():
data = pd.read_csv("data/clean_df.csv")
lm = LinearRegression()
img = io.BytesIO()
X = data[['highway-mpg']]
Y = data['price']
lm.fit(X, Y)
predict = np.around(np.array(lm.predict(X)))
intercept = lm.intercept_
slope = lm.coef_
plt.plot(X, predict)
plt.savefig(img, format='png')
img.seek(0)
plot = base64.b64encode(img.getvalue()).decode()
plt.close()
x = data['highway-mpg'].values.tolist()
y = data['price'].values.tolist()
result = {
'X': x[:50],
'Y': y[:50],
'Predicted': predict[:50],
'intercept': intercept,
'slope': slope,
'msqe': mean_squared_error(y, predict),
'r2': lm.score(X, predict),
'chart': plot
}
return result
如果我不使用plt.close(),它将导致所有图形变为相同的图形(在所有图形上绘制相同的数据)。但是使用
plt.close()
后,它会显示正确的图,但是现在我遇到了这个错误,这导致flask应用程序崩溃了,并且有一个消息框说Python崩溃了。遵循调试器显示的错误:
127.0.0.1 - - [05/Jul/2018 14:55:04] "GET /dashboard HTTP/1.1" 200 -
Exception ignored in: <bound method Image.__del__ of <tkinter.PhotoImage object at 0x000000644962F0F0>>
Traceback (most recent call last):
File "E:\ProgramData\Anaconda3\Lib\tkinter\__init__.py", line 3501, in __del__
self.tk.call('image', 'delete', self.name)
RuntimeError: main thread is not in main loop
Exception ignored in: <bound method Image.__del__ of <tkinter.PhotoImage object at 0x0000006449638048>>
Traceback (most recent call last):
File "E:\ProgramData\Anaconda3\Lib\tkinter\__init__.py", line 3501, in __del__
self.tk.call('image', 'delete', self.name)
RuntimeError: main thread is not in main loop
Exception ignored in: <bound method Image.__del__ of <tkinter.PhotoImage object at 0x00000064495AAA20>>
Traceback (most recent call last):
File "E:\ProgramData\Anaconda3\Lib\tkinter\__init__.py", line 3501, in __del__
self.tk.call('image', 'delete', self.name)
RuntimeError: main thread is not in main loop
Exception ignored in: <bound method Image.__del__ of <tkinter.PhotoImage object at 0x00000064495D5C50>>
Traceback (most recent call last):
File "E:\ProgramData\Anaconda3\Lib\tkinter\__init__.py", line 3501, in __del__
self.tk.call('image', 'delete', self.name)
RuntimeError: main thread is not in main loop
Exception ignored in: <bound method Image.__del__ of <tkinter.PhotoImage object at 0x00000064495B61D0>>
Traceback (most recent call last):
File "E:\ProgramData\Anaconda3\Lib\tkinter\__init__.py", line 3501, in __del__
self.tk.call('image', 'delete', self.name)
RuntimeError: main thread is not in main loop
Exception ignored in: <bound method Image.__del__ of <tkinter.PhotoImage object at 0x0000006448E629E8>>
Traceback (most recent call last):
File "E:\ProgramData\Anaconda3\Lib\tkinter\__init__.py", line 3501, in __del__
self.tk.call('image', 'delete', self.name)
RuntimeError: main thread is not in main loop
Exception ignored in: <bound method Image.__del__ of <tkinter.PhotoImage object at 0x0000006448EC8940>>
Traceback (most recent call last):
File "E:\ProgramData\Anaconda3\Lib\tkinter\__init__.py", line 3501, in __del__
self.tk.call('image', 'delete', self.name)
RuntimeError: main thread is not in main loop
Exception ignored in: <bound method Image.__del__ of <tkinter.PhotoImage object at 0x0000006448E69160>>
Traceback (most recent call last):
File "E:\ProgramData\Anaconda3\Lib\tkinter\__init__.py", line 3501, in __del__
self.tk.call('image', 'delete', self.name)
RuntimeError: main thread is not in main loop
Tcl_AsyncDelete: async handler deleted by the wrong thread
下图显示了显示的图以及错误:
Python crash error
最佳答案
就在行前
import matplotlib.pyplot as plt
加
import matplotlib
matplotlib.use('agg')
当前,matplotlib正在访问连接到GUI事件循环并导致意外行为的“ tkagg”后端。普通的“ agg”后端根本不连接到GUI。
关于python-3.x - 使用pyplot.close()会导致 flask 应用崩溃,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/51188461/