xiaohanyu

This gist and its comments contains some topics for technology section of data weekly

xiaohanyu

%% udp test client and server, from joe armstrong's "programming erlang, second
%% edition"
-module(udp_test).
-export([start_server/0, client/1]).

start_server() ->
    spawn(fun() -> server(4000) end).

%% the server
server(port) ->

xiaohanyu

%% socket examples from Joe Armstrong's "Programming Erlang, Second Edition".
-module(socket_examples).
-compile(export_all).
-import(lists, [reverse/1]).

string2value(Str) ->
    {ok, Tokens, _} = erl_scan:string(Str ++ "."),
    {ok, Exprs} = erl_parse:parse_exprs(Tokens),
    Bindings = erl_eval:new_bindings(),
    {value, Value, _} = erl_eval:exprs(Exprs, Bindings),

xiaohanyu

import unittest

def binary_search(array, t):
    l = 0
    h = len(array) - 1

    while (l <= h):
        m = (l + h) // 2
        if (array[m] == t):
            return m

xiaohanyu

Here’re two powerset function implemented in Python and Haskell.

import copy

def powerset(s):
    if s == []:
        return [[]]
    elif len(s) == 1:
        return [[], s]

xiaohanyu

This is a demo solution for exercise 10.1-1 of the famous CLRS’s Introduction to Algorithms, 3rd Edition book.

xiaohanyu

import Data.List

perm :: (Eq a) => [a] -> Int -> [[a]]
perm _ 0 = [[]]
perm xs r | length xs < r = [[]]
          | otherwise = [x:ys | x <- xs, ys <- perm (delete x xs) (r - 1)]

xiaohanyu

import matplotlib.pyplot as plt
import numpy as np

L = 6
x = np.linspace(0, L)
ncolors = len(plt.rcParams['axes.color_cycle'])
shift = np.linspace(0, L, ncolors, endpoint=False)
for s in shift:
    plt.plot(x, np.sin(x + s), 'o-')

xiaohanyu

defmodule Chop do
  def guess(final, range) do
    low..high = range
    middle = div(low + high, 2)
    _guess_helper(final, low, high, middle)
  end

  defp _guess_helper(final, _low, _high, middle) when final === middle do
    middle
  end

xiaohanyu

@font-face {
    font-family: 'Linux Libertine'; /* normal */
    src: url('/static/fonts/linux-libertine/LinLibertine_R.woff') format('woff');
    font-weight: normal;
    font-style: normal;
}

@font-face {
    font-family: 'Linux Libertine'; /* italic */
    src: url('/static/fonts/linux-libertine/LinLibertine_RI.woff') format('woff');