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How do you create nested dict in Python?
...he following:
d = {} # can use defaultdict(dict) instead
for row in file_map:
# derive row key from something
# when using defaultdict, we can skip the next step creating a dictionary on row_key
d[row_key] = {}
for idx, col in enumerate(row):
d[row_key][idx] = col
Ac...
Automatic Retina images for web sites
...
There is a new attribute for the img tag that allows you to add a retina src attribute, namely srcset. No javascript or CSS needed, no double loading of images.
<img src="low-res.jpg" srcset="high-res.jpg 2x">
Browser Support: http://caniuse.com/#search=srcset
O...
手机蓝牙控制台灯：HC-05 开关、无级调光、定时关灯（附 .aia 源码与单片机...
...给 Connect，组件会自己截取前面的地址。
when 列表选择器_设备.BeforePicking() {
列表选择器_设备.Elements = 蓝牙客户端1.AddressesAndNames
}
when 列表选择器_设备.AfterPicking() {
if 蓝牙客户端1.Connect(列表选择器_设备.Selection) {
微数据...
Get item in the list in Scala?
...
Use parentheses:
data(2)
But you don't really want to do that with lists very often, since linked lists take time to traverse. If you want to index into a collection, use Vector (immutable) or ArrayBuffer (mutable) or possibly Array (which is just a Java array, exc...
How to convert a SVG to a PNG with ImageMagick?
... to convert it into a PNG, then I get a 16x16 pixel PNG which is way too small:
18 Answers
...
machine learning libraries in C# [closed]
...asses:
public class TrainingSet
{
private readonly List<string> _attributes = new List<string>();
private readonly List<List<object>> _examples = new List<List<object>>();
public TrainingSet(params string[] attributes)
{
_attributes.AddRang...
micro:bit 实验02 - 按 A/B 键让屏幕上的小球跑起来 · App Inventor 2 中文网
...已失效，
本文用本站本地扩展。原文组件名写作 Microbit_Buttons，实际组件名是 Microbit_Button（无 s）。
一、器材清单
器材
数量
说明
BBC micro:bit
1
用板载的 A/B 两个...
Why does the default parameterless constructor go away when you create one with parameters
...ass, I most likely want to be able to instantiate that class. In order to allow that, the compiler must add a parameterless constructor, which will have no effect but to allow instantiation. This means that I don't have to include an empty constructor in my code just to make it work.
If I've defin...
What Every Programmer Should Know About Memory?
....
So, any book or article that describes something fundamental cannot be called outdated. "What every programmer should know about memory" is definitely worth to read, but, well, I don't think it's for "every programmer". It's more suitable for system/embedded/kernel guys.
...
MVC (Laravel) where to add logic
...
I think all patterns / architectures that you present are very useful as long as you follow the SOLID principles.
For the where to add logic I think that it's important to refer to the Single Responsibility Principle. Also, my answe...