小编Pas*_*age的帖子

设 X, Y 为 2 个随机变量，概率密度函数为 pdf1 和 pdf2。

Z = X + Y

那么Z的概率密度函数由pdf1和pdf2的卷积给出。由于我们无法处理连续分布，我们描述了连续分布并处理它们。

为了找到均匀分布和正态分布的卷积，我想出了以下代码。

import matplotlib.pyplot as plt
import numpy as np
import scipy.stats as stats
from scipy import signal


uniform_dist = stats.uniform(loc=2, scale=3)
std = 0.25
normal_dist = stats.norm(loc=0, scale=std)

delta = 1e-4
big_grid = np.arange(-10,10,delta)

pdf1 = uniform_dist.pdf(big_grid)
print("Integral over uniform pdf: "+str(np.trapz(pdf1, big_grid)))

pdf2 = normal_dist.pdf(big_grid)
print("Integral over normal pdf: "+str(np.trapz(pdf2, big_grid)))


conv_pdf = signal.fftconvolve(pdf1,pdf2,'same')
print("Integral over convoluted pdf: "+str(np.trapz(conv_pdf, big_grid)))

plt.plot(big_grid,pdf1, label='Tophat')
plt.plot(big_grid,pdf2, label='Gaussian …

给定一组数据值，我试图获得能够很好地描述数据的最佳理论分布。经过几天的研究，我想出了以下 python 代码。

import numpy as np
import csv
import pandas as pd
import scipy.stats as st
import math
import sys
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt

def fit_to_all_distributions(data):
    dist_names = ['fatiguelife', 'invgauss', 'johnsonsu', 'johnsonsb', 'lognorm', 'norminvgauss', 'powerlognorm', 'exponweib','genextreme', 'pareto']

    params = {}
    for dist_name in dist_names:
        try:
            dist = getattr(st, dist_name)
            param = dist.fit(data)

            params[dist_name] = param
        except Exception:
            print("Error occurred in fitting")
            params[dist_name] = "Error"

    return params 


def get_best_distribution_using_chisquared_test(data, params):

    histo, bin_edges = np.histogram(data, bins='auto', normed=False)
    number_of_bins …

JAVA NIO提供了使用NIO架构编写TCP服务器的API，如下所示。

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.text.ParseException;
import java.util.*;

public class NIOServer implements Runnable{
    private InetAddress addr;
    private int port;
    private Selector selector;

    public NIOServer(InetAddress addr, int port) throws IOException {
        this.addr = addr;
        this.port = port;
    }

    public void run(){
        try {
            startServer();
        }catch(IOException ex){
            System.out.println(ex.getMessage());
        }
    }

    private void startServer() throws IOException {

        this.selector = Selector.open();
        ServerSocketChannel serverChannel = …