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An algorithm for randomly generating integer partitions of a particular length, in Python?

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问题 I've been using the random_element() function provided by SAGE to generate random integer partitions for a given integer ( N ) that are a particular length ( S ). I'm trying to generate unbiased random samples from the set of all partitions for given values of N and S . SAGE's function quickly returns random partitions for N (i.e. Partitions(N).random_element() ). However, it slows immensely when adding S (i.e. Partitions(N,length=S).random_element() ). Likewise, filtering out random

武汉光迅科技Java笔试题

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1.Java中的override和overload的区别？ override（重写）：指子类继承父类，重写父类中的方法。 overload（重载）：指用一个类中，方法名相同，传参个数不同、参数类型不同、传参顺序不同的方法，与方法返回类型无关。 2.什么是值传递什么是引用传递？值传递：传递的是存储单元中的内容，而非地址或者引用！引用传递：引用传递是指在调用函数时将实际参数的地址传递到函数中，那么在函数中对参数所进行的修改，将影响到实际参数。 Java中只有按值传递，没有按引用传递！ 3.创建线程有几种方式？你喜欢哪一种，为什么？创建线程有三种方法： 1.继承Thread类，重写run方法； 2.实现Runnable的方法； 3.使用ExecutorService、Callable、Future实现有返回结果的多线程；但多数时间我们实现Runnable，因为java支持多实现，但不支持多继承。 4.ES是什么？简述他的优点。 ES（Elasticsearch）是一个基于Lucene的搜索服务器。 ES是分布式的不需要其他组件，分发是实时的； ES实时搜索非常快； ES处理多租户不需要特殊配置，学习成本较低； 5.简述你所知道的mysql的分库分表方案？垂直拆分垂直分表也就是“大表拆小表”，基于列字段进行的。一般是表中的字段较多，将不常用的，数据较大，长度较长

iPython: Manipulate-like command

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问题 In Wolfram Mathematica, I can interactively modify the value of a parameter by using the Manipulate[] command. For example, Manipulate[n, {n, 1, 20}] shows a slider through which is possible to vary the value of n . Is there any simple way (i.e. something like a magic or a decorator, like in SAGE) to achieve the same result in the IPython notebook? 回答1: Update This was added in IPython 2.0 (released Apr 1, 2014), it's called Interactive Widgets and works in web notebooks. Original answer This

Launch Pycharm from command line (terminal)

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I want to try out PyCharm for sage mathematics development. Normally I run eclipse to do sage development, but now I want to try it with PyCharm. To launch eclipse with sage environment variables, in command line I normally do the following: sage -sh cd /path/to/eclipse ./eclipse The first line loads the sage environment variables, the remainder launches eclipse. How can I do the same thing for pyCharm? (note I am using a Mac and Ubuntu for sage development; the commands above are agnostic to both OSes) Link 1 is close to the solution I am looking for, however I cannot find a pyCharm.sh

SciPy Create 2D Polygon Mask

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I need to create a numpy 2D array which represents a binary mask of a polygon, using standard Python packages. input: polygon vertices, image dimensions output: binary mask of polygon (numpy 2D array) (Larger context: I want to get the distance transform of this polygon using scipy.ndimage.morphology.distance_transform_edt.) Can anyone show me how to do this? The answer turns out to be quite simple: import numpy from PIL import Image, ImageDraw # polygon = [(x1,y1),(x2,y2),...] or [x1,y1,x2,y2,...] # width = ? # height = ? img = Image.new('L', (width, height), 0) ImageDraw.Draw(img).polygon

Launch Pycharm from command line (terminal)

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问题 I want to try out PyCharm for sage mathematics development. Normally I run eclipse to do sage development, but now I want to try it with PyCharm. To launch eclipse with sage environment variables, in command line I normally do the following: sage -sh cd /path/to/eclipse ./eclipse The first line loads the sage environment variables, the remainder launches eclipse. How can I do the same thing for pyCharm? (note I am using a Mac and Ubuntu for sage development; the commands above are agnostic to

SciPy Create 2D Polygon Mask

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问题 I need to create a numpy 2D array which represents a binary mask of a polygon, using standard Python packages. input: polygon vertices, image dimensions output: binary mask of polygon (numpy 2D array) (Larger context: I want to get the distance transform of this polygon using scipy.ndimage.morphology.distance_transform_edt.) Can anyone show me how to do this? 回答1: The answer turns out to be quite simple: import numpy from PIL import Image, ImageDraw # polygon = [(x1,y1),(x2,y2),...] or [x1,y1

实验三：数据更新和视图操作

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1.创建表student create table student( sno varchar2(20) primary key, sname varchar2(20), ssex varchar2(10), sdept varchar2(20), sage number ); 2.将一个新学生元组插入到表 student （学号：200815128；姓名：陈冬；性别：男；所在系：计算机学院；年龄：18 岁） insert into student(sno, sname, ssex, sdept, sage) values('200815128', '李东', '男', '计算机学院', 18); 3.创建表dept_sage create table dept_sage( sdept varchar2(20), avg_age number ); 4.计算学生的平均年龄，插入dept_sage表 insert into dept_sage(sdept, avg_age) select sdept, avg(sage) from student group by sdept; 5.将学生 200815128 的年龄改为 22 岁 update student set sage = 22 where sno = '200815128'; 6.创建表sc create table sc(