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How do I compute derivative using Numpy?
...es
Automatic Derivatives
Symbolic Differentiation
Compute derivatives by hand.
Finite differences require no external tools but are prone to numerical error and, if you're in a multivariate situation, can take a while.
Symbolic differentiation is ideal if your problem is simple enough. Symbolic...
Deserializing JSON to .NET object using Newtonsoft (or LINQ to JSON maybe?)
...ecause you don't need to fully deserialize the JSON object. This comes in handy with APIs that can sometimes surprise you with missing object properties, like Twitter.
Documentation: Serializing and Deserializing JSON with Json.NET and LINQ to JSON with Json.NET
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When to use -retainCount?
I would like to know in what situation did you use -retainCount so far, and eventually the problems that can happen using it.
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WebAPI Multiple Put/Post parameters
...ost multiple parameters on a WebAPI controller. One param is from the URL, and the other from the body. Here is the url:
/offers/40D5E19D-0CD5-4FBD-92F8-43FDBB475333/prices/
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`levels
...answers here are good, but they are missing an important point. Let me try and describe it.
R is a functional language and does not like to mutate its objects. But it does allow assignment statements, using replacement functions:
levels(x) <- y
is equivalent to
x <- `levels<-`(x, y)
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Python 3 turn range to a list
...gh since you can come by the value of my_list[i] more efficiently (i + 1), and if you just need to iterate over it, you can just fall back on range.
Also note that on python2.x, xrange is still indexable1. This means that range on python3.x also has the same property2
1print xrange(30)[12] works ...
Get battery level and state in Android
How can I get battery level and state (plugged in, discharging, charging, etc)? I researched the developer docs and I found a BatteryManager class. But it doesn't contain any methods, just constants. How do I even use it?
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Why does Razor _layout.cshtml have a leading underscore in file name?
... doesn't have the same sort of protection built in regarding Views folders and Routing that you get within MVC. Since layout pages in Web Pages are not intended to be served directly, they are prefixed with the underscore. And the Web Pages framework has been configured not to allow files with leadi...
Configure apache to listen on port other than 80
...ed LISTEN 8079 directive in httpd.conf .
I opened port 8079 in iptables and restarted iptables. I even stopped iptables service.
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How does a public key verify a signature?
...m trying to get a better grapple on how public/private keys work. I understand that a sender may add a digital signature to a document using his/her private key to essentially obtain a hash of the document, but what I do not understand is how the public key can be used to verify that signature.
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