大约有 48,000 项符合查询结果（耗时：0.0559秒） [XML]
Bogus foreign key constraint fail
...each query (bugs.mysql.com/bug.php?id=8280), making it neccessary to write all the drop statements in one query, eg.
SET FOREIGN_KEY_CHECKS=0;
DROP TABLE my_first_table_to_drop;
DROP TABLE my_second_table_to_drop;
SET FOREIGN_KEY_CHECKS=1;
Where the SET FOREIGN_KEY_CHECKS=1 serves as an extr...
Python Image Library fails with message “decoder JPEG not available” - PIL
...you are on 64bit or 32bit Ubuntu.
For Ubuntu x64:
sudo ln -s /usr/lib/x86_64-linux-gnu/libjpeg.so /usr/lib
sudo ln -s /usr/lib/x86_64-linux-gnu/libfreetype.so /usr/lib
sudo ln -s /usr/lib/x86_64-linux-gnu/libz.so /usr/lib
Or for Ubuntu 32bit:
sudo ln -s /usr/lib/i386-linux-gnu/libjpeg.so /usr/l...
Python argparse: default value or specified value
...
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('--example', nargs='?', const=1, type=int)
args = parser.parse_args()
print(args)
% test.py
Namespace(example=None)
% test.py --example
Namespace(example=1)
% test.py --example 2
Namespace(example=2)
nargs...
vagrant up failed, /dev/vboxnetctl: no such file or directory
Can be useful, I found this error. The common solution is reinstall virtualbox but there are a better way.
8 Answers
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MySQL Orderby a number, Nulls last
... tablename WHERE visible=1 ORDER BY -position DESC, id DESC
It is essentially the inverse of position DESC placing the NULL values last but otherwise the same as position ASC.
A good reference is here http://troels.arvin.dk/db/rdbms#select-order_by
...
Bin size in Matplotlib (Histogram)
...width in this example could be found by: (data.max() - data.min()) / number_of_bins_you_want. The + binwidth could be changed to just 1 to make this a more easily understood example.
– Jarad
Jan 22 '18 at 17:31
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How to convert a string or integer to binary in Ruby?
...
You would naturally use Integer#to_s(2), String#to_i(2) or "%b" in a real program, but, if you're interested in how the translation works, this method calculates the binary representation of a given integer using basic operators:
def int_t...
Global access to Rake DSL methods is deprecated
...
You can "delete" Rake 0.9.1 by running the following command:
gem uninstall rake -v=0.9.1
If you have multiple versions of the gem installed, you'll be prompted to pick a version.
After 0.9.1 was cleaned out, I ran
bundle update rake
and was finally able to create my database files. I was ...
Detect encoding and make everything UTF-8
...ng, it will return garbled UTF-8 output.
I made a function that addresses all this issues. It´s called Encoding::toUTF8().
You don't need to know what the encoding of your strings is. It can be Latin1 (ISO 8859-1), Windows-1252 or UTF-8, or the string can have a mix of them. Encoding::toUTF8() wi...
Filter rows which contain a certain string
...n easily extend to more than one column.
Below also a solution with filter_all in order to find the string in any column,
using diamonds as example, looking for the string "V"
library(tidyverse)
String in only one column
# for only one column... extendable to more than one creating a column list in...