Error Messages:
RuntimeError: Invalid DISPLAY variable
Solution:
add the following codes
plt.switch_backend('agg')
after this line
import matplotlib.pyplot as plt
Done!
Tag Archives: Python Learning Notes
Python AttributeError: ‘bool‘ object has no attribute ‘ui‘
Error code:
The defined method is a static function. In fact, the function content is not static, so an error occurs when calling. Just delete @ staticmethod.
Correct code:
python cx_Oracle.DatabaseError: Error while trying to retrieve text for error ORA-01804
Problem Description:
Using Python package CX_ When setting scheduled tasks on the Oracle server, errors are always reported, such as the title, but running alone is no problem
resolvent:
Under the guidance of the boss, add a few lines of code in front of the script to solve the problem perfectly. The environment variable path is configured according to its own path.
import os
os.environ["ORACLE_HOME"] = '/home/oracle/app/oracle/product/11.2.0/dbhome_1'
os.environ["ORACLE_BASE"] = '/home/oracle/app/oracle'
os.environ["ORACLE_SID"] = 'orcl'
os.environ["LD_LIBRARY_PATH"] = '/home/oracle/app/oracle/product/11.2.0/dbhome_1/lib:/lib:/usr/lib'UserWarning: Failed to initialize NumPy: No module named ‘numpy.core._multiarray_umath‘
This error is usually caused by the mismatch of numpy versions, and the related MKL libraries are also uninstalled
pip unstall numpy
pip unstall mkl-serviceThen PIP reinstall it
I just don’t know why I can’t solve it with CONDA uninstall + reinstall. Just replace it with PIP. It seems that there is a difference between uninstall and installed library?
Attributeerror: the solution of module ‘urllib’ has no attribute ‘quote’
Record:
Today, I saw the interface document provided by others. When parsing the text, I used urllib.quote In the end, we found that it was a version problem. The way to write python2 is urllib.quote , python3 should be changed to urllib.parse.quote That’s it.
Pre initialization of list content and length in Python
If you want to set the same initial value and desired length
>>> a=[None]*4
>>> print(a)
[None, None, None, None]If we know the length of the list in advance, we can initialize the list of that length in advance, and then assign values to each list, which will be faster than each time list.append () more efficient.
If you want the sequence initial value, you can use the range function, but note that the range function returns an iterative object, which needs to be converted into a list
>>> b=list(range(10))
>>> print(b)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> b=range(10)
>>> print(b)
range(0, 10)If you want to eliminate unwanted data, you can use the list derivation
>>> c=[i for i in range(10) if i%2==0 and i<8]
>>> print(c)
[0, 2, 4, 6]Life is short, You need Python~
When Python Django creates a database, can’t open file ‘ manage.py ‘: [Errno 2] No such file or directory
1. When creating a database after learning Diango new project, use the following command:
python manage.py migrate‘can’t open file ‘manage.py’: [Errno 2] No such file or directory’ can’t open file ‘manage.py’: [Errno 2] No such file or directory ‘can’t open file ‘manage.py’: [Errno 2] No such file or directory’
Django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py: django-admin.py:
django-admin.py startproject student_project .4, then report the above described error, the reason: in fact, the path is wrong, did not set the soft connection. F:\python_stu\student_project\stu_env\Lib\site-packages\ Django \bin. Django-admin.py: F:\python_stu\student_project\stu_env\Lib\site-packages\ Django \bin.
python F:\python_stu\student_project\stu_env\Lib\site-packages\django\bin\django-admin.py startproject student_projectThe above content is only for your reference, thank you!