Singleton mode seems to be simple in fact, there are a lot of problems to consider.

The above problems, no one will be particularly distressed, but piled up, but let our development efficiency and development experience lag several grades. These questions are not solvable, and we can try to help colleagues and teams find answers to questions such as:

Unify the team's local build environment and initialize scaffolding for a project catalog
Unified packaging script, real-time compilation and preview
Encapsulation preprocessing base class, shielding REM calculations, such as automatic conversion of PX to REM at compile time
Build cloud testing platform, cloud test various model compatibility, open Web page input URL to batch test
Some solutions can be done with just a few lines of scripting, and some may need to invest time and effort.

Get Data

Local, pre-hair, online three sets of environment, how to achieve the smooth transition of the environment? When I was in Baidu, the most common solution for the team was:

On-line testing, local reverse proxy to pre-or online environment;
Local test, the mock interface is provided using Apache open service
Once the interface with the backend is changed, the local mock data will be changed along with it. What is the best solution to this problem? In the team, the good plan must not be a few lines of text tips or guidelines, but through the process and monitoring to control!

Distance measurement of 2.1 KNN algorithm

The distance + from the two instance points in the feature space is the reaction of the similarity of two instance points. (Be sure to focus on understanding, you can take a single dog to think about). The characteristic space of K-nearest neighbor model is generally n-dimensional real vector space Rn. The distance used is European-style, but can also be other distances, such as more general LP distance (LP distance) or Minkowski distance (Minkowski distance)

1. Euclidean distance, the most common distance representation between two points or multipoint, also known as Euclid's metric, is defined in Euclidean space, such as the distance between points x = (x1,..., xn) and y = (y1,..., yn):

2. Manhattan distance, Manhattan distance depends on the rotation of the coordinate system, rather than the translation or mapping of the system on the coordinates.

As you can see, the above request contains three parts: Requests line, header, message, more than the previous GET request a message body, where the header and message body separated by a blank line. The parameters of the POST request are not in the URL, but in the message body, where a content-length is used to represent the number of bytes in the message body, so that the server knows whether the request was sent or not. This is the main difference between a GET request and a POST request.

HTTP responses are very similar to HTTP requests, and the HTTP response consists of three parts: status line, header, massage body. Where status line contains protocol version, status code, reason phrase three parts. Status codes are used to describe the status of HTTP responses, such as 200 for success, 404 for resources not found, and 500 for server errors.

This step mainly through the Pyplot to draw the data, through the graph, you can have an intuitive sense of the data, you can roughly determine the first choice between the three feature and class whether there is a certain regularity between the relationship. Drawing the Code:

With the worldwide popularity of the internet, the data is so large that it is difficult to cope with the existing data management methods or traditional data processing applications. The large, broad data sets mentioned above are called Big data.

Xiao Ming a look at the above pattern, his sudden strange, a hungry man mode anxious to create the object, in the load time consumption performance, and lazy mode and there is a thread safety problem (after optimization did not) can combine it, suddenly told the interviewer I have a better way to achieve, and then he wrote the following code

Singleton mode seems to be simple in fact, there are a lot of problems to consider.