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Sparse, L1-minimization, Compressive Sensing 集中讨论帖(第一页常更新)Sparse大家并不陌生,是个经典话题了。而此时 sparse已经卷土重来,虽然还是那一锅汤,但是药已经换了。以 L1-minimization为核心的算法,近几年飞速进展, Compressive Sensing ( Compressive Sampling) 已然成为数学领域和信号处理最前沿最热门的方向。最近一年多这种新形式的算法快速蔓延到模式识别界应用, 论文质量高、算法效果好、而且算法一般都非常简单。 而这仅仅是个开始,所以我一直有这个想法专开一贴,供大家一起讨论、共同进步,今天付诸与行动,希望大家支持。在这个地方(第一个帖),我会陆续更新提供一些这方面的材料,供大家了解。如果大家提供了有趣的材料,我也尽量加进来。当然, 此贴重点还是放在理论应用和模式识别上。大家踊跃发言啊! Compressive Sensing资源主页: Compressive Sensing Resources (最权威最全面的Compressive Sensing资源主页,几乎什么都能找的到); Compressive Sensing (和上面的差不多); Compressive Sensing Listing; 马毅的课程主页Compressive Sensing Videos; Compressed Sensing Codes (还有 Compressive Sensing Resources 的Software一栏中); Nuit Blanche; Compressive Sensing: The Big Picture; Terence Tao's What's new; 理论方面的代表人物: David Donoho; Emmanuel Candes; TutorialsEmmanuel Candès, Compressive sampling. (Int. Congress of Mathematics, 3, pp. 1433-1452, Madrid, Spain, 2006) Richard Baraniuk, Compressive sensing. (IEEE Signal Processing Magazine, 24(4), pp. 118-121, July 2007) Emmanuel Candès and Michael Wakin, An introduction to compressive sampling. (IEEE Signal Processing Magazine, 25(2), pp. 21 - 30, March 2008) Justin Romberg, Imaging via compressive sampling. (IEEE Signal Processing Magazine, 25(2), pp. 14 - 20, March 2008) Conferences and SymposiumsShort Course: Sparse Representations and High Dimensional Geometry, May 30 - June 1, 2007 New Directions Short Course: Compressive Sampling and Frontiers in Signal Processing, June 4 - 15, 2007 ( 介绍性的资料和视频) 理论方面的代表文献: Donoho 和 Candes 的文章几乎都是经典模式识别领域的应用(包括机器视觉): 大家可以去 Compressive Sensing Resources 看 Statistical Signal Processing, Machine Learning, Bayesian Methods, Applications of Compressive Sensing 等栏目 马毅的一系列论文John Wright, Allen Yang, Arvind Ganesh, Shankar Shastry, and Yi Ma, Robust face recognition via sparse representation. (To appear in IEEE Trans. on Pattern Analysis and Machine Intelligence) , 2008 Allen Yang, John Wright, Yi Ma, and Shankar Sastry, Feature selection in face recognition: A sparse representation perspective. (Preprint, 2007) Kwak, N., Principal Component Analysis Based on L1-Norm Maximization, IEEE Transactions on Pattern Analysis and Machine Intelligence, 2008. Bhusnurmath, Arvind; Taylor, Camillo J., Graph Cuts via $ell_1$ Norm Minimization, IEEE Transactions on Pattern Analysis and Machine Intelligence, 2008. Jianchao Yang, John Wright, Thomas Huang, and Yi Ma, Image Super-Resolution as Sparse Representation of Raw Image Patches, IEEE Conference on Computer Vision and Pattern Recognition (CVPR), June 2008. Arvind Ganesh, Zihan Zhou, and Yi Ma, Separation of A Subspace-Sparse Signal: Algorithms and Conditions, ICASSP 2009.
阅读文献的一点心得
1. 先看综述,后看论著看综述搞清概念,看论著掌握方法。
2. 早动手在师兄师姐离开之前学会关键技术。
3. 多数文章看摘要,少数文章看全文掌握了一点查全文的技巧,往往会以搞到全文为乐,以至于没有时间看文章的内容,更不屑于看摘要。真正有用的全文并不多,过分追求全文是浪费,不可走极端。当然只看摘要也是不对的。
4. 集中时间看文献看过总会遗忘。看文献的时间越分散,浪费时间越多。集中时间看更容易联系起来,形成整体印象。
5. 做好记录和标记复印或打印的文献,直接用笔标记或批注。pdf 或html 格式的文献,可以用编辑器标亮或改变文字颜色。这是避免时间浪费的又一重要手段。否则等于没看。
6. 准备引用的文章要亲自看过。转引造成的以讹传讹不胜枚举。
7. 注意文章的参考价值。刊物的影响因子、文章的被引次数能反映文章的参考价值。但要注意引用这篇文章的其它文章是如何评价这篇文章的:支持还是反对,补充还是纠错。
8. 交流是最好的老师做实验遇到困难是家常便饭。你的第一反应是什么?反复尝试?放弃?看书?这些做法都有道理,但首先应该想到的是交流。对有身份的人,私下的请教体现你对他的尊重;对同年资的人,公开的讨论可以使大家畅所欲言,而且出言谨慎。千万不能闭门造车。一个实验折腾半年,后来别人告诉你那是死路,岂不冤大头?
9. 最高层次的能力是表达能力再好的工作最终都要靠别人认可。表达能力,体现为写和说的能力,是需要长期培养的素质。比如发现一个罕见病例,写好了发一篇论著;写不好只能发一个病例报道。比如做一个课题,写好了发一篇或数篇论著;写不好只能发一个论著摘要或被枪毙。一张图,一张表,无不是表达能力的体现。寥寥几百上千字的标书,可以赢得大笔基金;虽然关系很重要,但写得太差也不行。有人说,我不学PCR,不学spss,只要学会ppt(powerpoint)就可以了。此话有一点道理,实验室的boss 们表面上就是靠一串串ppt 行走江湖的。经常有研究生因思维敏捷条例清楚而令人肃然起敬。也经常有研究生不理解"为什么我做了大部分工作而老板却让另一个没怎么干活的人写了文章?让他去大会发言?"你没有看到人家有张口就来的本事吗?
10. 学好英语,不学二外。如今不论去日本还是欧洲,学术交流早已是英语的天下。你不必为看不懂一篇法语的文章而遗憾,写那篇文章的人正在为没学好英语而犯愁。如果英文尚未精通,暂且不要去学二外。
文献管理
1. 下载电子版文献时(caj,pdf,html),把文章题目粘贴为文件名。注意,文件名不能有特殊符号,要把 \ / : * ? < > | 以及 换行符删掉。 每次按照同样的习惯设置文件名,可以防止重复下载。
2. 不同主题存入不同文件夹。文件夹的题目要简短,如:PD,LTP,PKC,NO。
3. 看过的文献归入子文件夹,最起码要把有用的和没用的分开。
4. 重要文献根据重要程度在文件名前加001,002,003 编号,然后按名称排列图标,最重要的文献就排在最前了。
Cover letter:
关于英文投稿时的cover letter, 以下有三种写法,各有其特色,但本人认为,核心点在于:所做工作的新颖性和关键点,尤其是所做工作解决了什么科学问题。cover letter 不易过长,关且注意:这部分是给主编看的!因此,要用最短的文字来说服主编你的文章值得该刊发表。
附: Case 1Dear Editor, We would like to submit the enclosed manuscript entitled "GDNF Acutely Modulates Neuronal Excitability and A-type Potassium Channels in Midbrain Dopaminergic Neurons", which we wish to be considered for publication in Nature Neuroscience. GDNF has long been thought to be a potent neurotrophic factor for the survival of midbrain dopaminergic neurons, which are degenerated in Parkinson’s disease. In this paper, we report an unexpected, acute effect of GDNF on A-type potassium channels, leading to a potentiation of neuronal excitability, in the dopaminergic neurons in culture as well as in adult brain slices. Further, we show that GDNF regulates the K+ channels through a mechanism that involves activation of MAP kinase. Thus, this study has revealed, for the first time, an acute modulation of ion channels by GDNF. Our findings challenge the classic view of GDNF as a long-term survival factor for midbrain dopaminergic neurons, and suggest that the normal function of GDNF is to regulate neuronal excitability, and consequently dopamine release. These results may also have implications in the treatment of Parkinson’s disease. Due to a direct competition and conflict of interest, we request that Drs. XXX of Harvard Univ., and YY of Yale Univ. not be considered as reviewers. With thanks for your consideration, I am Sincerely yours, case2Dear Editor, We would like to submit the enclosed manuscript entitled "Ca2+-binding protein frequenin mediates GDNF-induced potentiation of Ca2+ channels and transmitter release", which we wish to be considered for publication in Neuron. We believe that two aspects of this manuscript will make it interesting to general readers of Neuron. First, we report that GDNF has a long-term regulatory effect on neurotransmitter release at the neuromuscular synapses. This provides the first physiological evidence for a role of this new family of neurotrophic factors in functional synaptic transmission. Second, we show that the GDNF effect is mediated by enhancing the expression of the Ca2+-binding protein frequenin. Further, GDNF and frequenin facilitate synaptic transmission by enhancing Ca2+ channel activity, leading to an enhancement of Ca2+ influx. Thus, this study has identified, for the first time, a molecular target that mediates the long-term, synaptic action of a neurotrophic factor. Our findings may also have general implications in the cell biology of neurotransmitter release. [0630][投稿写作]某 杂志给出的标准S ample Cover Letter[the example used is the IJEB] Case 3Sample Cover Letter[the example used is the IJEB] Dear Editor of the [please type in journal title or acronym]: Enclosed is a paper, entitled "Mobile Agents for Network Management." Please accept it as a candidate for publication in the [journal title]. Below are our responses to your submission requirements. 1. Title and the central theme of the article. Paper title: "Mobile Agents for Network Management." This study reviews the concepts of mobile agents and distributed network management system. It proposes a mobile agent-based implementation framework and creates a prototype system to demonstrate the superior performance of a mobile agent-based network over the conventional client-server architecture in a large network environment. 2. Which subject/theme of the Journal the material fits New enabling technologies (if no matching subject/theme, enter 'Subject highly related to [subject of journal] but not listed by [please type in journal title or acronym]) 3. Why the material is important in its field and why the material should be published in [please type in journal title or acronym]? The necessity of having an effective computer network is rapidly growing alongside the implementation of information technology. Finding an appropriate network management system has become increasingly important today's distributed environment. However, the conventional centralized architecture, which routinely requests the status information of local units by the central server, is not sufficient to manage the growing requests. Recently, a new framework that uses mobile agent technology to assist the distributed management has emerged. The mobile agent r educes network traffic, distributes management tasks, and improves operational performance. Given today's bandwidth demand over the Internet, it is important for the [journal title/acronym] readers to understand this technology and its benefits. This study gives a real-life example of how to use mobile agents for distributed network management. It is the first in the literature that reports the analysis of network performance based on an operational prototype of mobile agent-based distributed network. We strongly believe the contribution of this study warrants its publication in the [journal title/acronym]. 4. Names, addresses, and email addresses of four expert referees. Prof. Dr. William Gates Chair Professor of Information Technology 321 Johnson Hall Premier University Lancaster, NY 00012-6666, USA phone: +1-888-888-8888 - fax: +1-888-888-8886 e-mail: wgates@lancaster.edu Expertise: published a related paper ("TCP/IP and OSI: Four Strategies for Interconnection") in CACM, 38(3), pp. 188-198. Relationship: I met Dr. Gate only once at a conference in 1999. I didn't know him personally. Assoc Prof. Dr. John Adams Director of Network Research Center College of Business Australian University 123, Harbor Drive Sydney, Australia 56789 phone: +61-8-8888-8888 - fax: +61-8-8888-8886 e-mail: jadams@au.edu.au Expertise: published a related paper ("Creating Mobile Agents") in IEEE TOSE, 18(8), pp. 88-98. Relationship: None. I have never met Dr. Adams. Assoc Prof. Dr. Chia-Ho Chen Chair of MIS Department College of Management Open University 888, Putong Road Keelung, Taiwan 100 phone: +886-2-8888-8888 - fax: +886-2-8888-8886 e-mail: chchen@ou.edu.tw Expertise: published a related paper ("Network Management for E-Commerce") in IJ Electronic Business, 1(4), pp. 18-28. Relationship: Former professor, dissertation chairman. Mr. Frank Young Partner, ABC Consulting 888, Seashore Highway Won Kok, Kowloon Hong Kong phone: +852-8888-8888 - fax: +852-8888-8886 e-mail: fyoung@abcc.com Expertise: Mr. Young provides consulting services extensively to his clients regarding network management practices. Relationship: I have worked with Mr. Young in several consulting projects in the past three years. Finally, this paper is our original unpublished work and it has not been submitted to any other journal for reviews. Sincerely, Johnny Smith
如何使EndNote显示所有作者? 菜单里Edit->Output stytles->比如选中Edit "IEEE”,Author lists,选中"List all authors”即可 Remove field codes、Editor如何查找(1) Remove field codes在Endnote X4中,在word2007,Endnote X4菜单,中间Bibilography,在Convert citations and Bibilography的Convert to plain text (2) AI in medicine 这个杂志要求:Add the editors in reference of conference proceedings。怎么找会议的editor呢?
以The 2007 International Conference of Data Mining and Knowledge Engineering为例,怎么查找editor?到该会议主页,contact us->Editorial board->Editors
总而言之,一个会议的网页上应该包含了你所需要的所有信息,诸如Editors之类。
但是NIPS 2004 没找到
要求添加Semi-supervised learning using Gaussian fields and harmonic functions.这篇论文的:the editors, the publishing company, and the place of the publishing company in references of conference proceedings.解决方案:到谷歌上搜索www.informatik.uni-trier.de icml 2003 就能找到。 多日想不出此问题的解决方案,经过shuling wang老师提醒,终结解决方案:到web of science上搜,editors和publisher这些信息均能找到,如NIPS上论文learning with local and global consistency和Feature extraction from tumor gene expression profiles using DCT and DFT均能找到
EndNote在LaTeX中的运用 本课件帮助科研人员在LaTeX文本编辑环境下如何利用EndNote软件编辑参考文献。
EndNote在LaTeX中的运用 (Understand completely) BibTeX Export_Sww.ens. 首次:在Endnote菜单中选择Edit->Output sytle-> Open style manger-> 选中BibTex export;以后:只要Edit->Output sytle-> BibTex export ,则Endnote中的文献以Latex的方式呈现
在Endnote中查找那些已经在enl中有的文件 在Endnote工具栏中有搜索按钮,搜索对应论文的标题即可
4.1 字符串数组
4.1.1 字符串入门
【 * 例 4.1.1 -1 】先请读者实际操作本例,以体会数值量与字符串的区别。 clear % 清除所有内存变量 a=12345.6789 % 给变量 a 赋数值标量 class(a) % 对变量 a 的类别进行判断 a_s=size(a) % 数值数组 a 的“大小” a = 1.2346e+004 ans = double a_s = 1 1
b='S' % 给变量 b 赋字符标量(即单个字符) class(b) % 对变量 b 的类别进行判断 b_s=size(b) % 符号数组 b 的“大小” b = S ans = char b_s = 1 1 whos % 观察变量 a,b 在内存中所占字节 Name Size Bytes Class a 1x1 8 double array a_s 1x2 16 double array ans 1x4 8 char array b 1x1 2 char array b_s 1x2 16 double array Grand total is 10 elements using 50 bytes
4.1.2 串数组的属性和标识
【 * 例 4.1.2 -1 】本例演示:串的基本属性、标识和简单操作。
(1)创建串数组 a='This is an example.' a = This is an example.
(2)串数组 a 的大小 size(a) ans = 1 19
(3)串数组的元素标识 a14=a(1:4) % 提出一个子字符串 ra=a(end:-1:1) % 字符串的倒排 a14 = This ra = .elpmaxe na si sihT
(4)串数组的 ASCII 码 ascii_a=double(a) % 产生 ASCII 码 ascii_a = Columns 1 through 12 84 104 105 115 32 105 115 32 97 110 32 101 Columns 13 through 19 120 97 109 112 108 101 46 char(ascii_a) % 把 ASCII 码变回字符串 ans = This is an example.
(5)对字符串 ASCII 码数组的操作 % 使字符串中字母全部大写 w=find(a>='a'&a<='z'); % 找出串数组 a 中,小写字母的元素位置。 ascii_a(w)=ascii_a(w)-32; % 大小写字母 ASCII 值差 32. 用数值加法改变部分码值。 char(ascii_a) % 把新的 ASCII 码翻成字符 ans = THIS IS AN EXAMPLE.
(6)中文字符串数组 A=' 这是一个算例。 '; % 创建中文字符串 A_s=size(A) % 串数组的大小 A56=A([5 6]) % 取串的子数组 ASCII_A=double(A) % 获取 ASCII 码 A_s = 1 7 A56 =
算例 ASCII_A = Columns 1 through 6 54754 51911 53947 47350 52195 49405 Column 7 41379
char(ASCII_A) % 把 ASCII 码翻译成字符 ans = 这是一个算例。
(7)创建带单引号的字符串 b='Example '' 4.1.2 -1''' b = Example ' 4.1.2 -1'
(8)由小串构成长串 ab=[a(1:7),' ',b,' .'] % 这里第 2 个输入为空格串 ab = This is Example ' 4.1.2 -1' .
4.1.3 复杂串数组的创建
4.1.3.1 多行串数组的直接创建
【 * 例 4.1.3 .1-1 】多行串数组的直接输入示例。 clear S=['This string array ' 'has multiple rows.'] S = This string array has multiple rows. size(S) ans = 18
4.1.3.2 利用串操作函数创建多行串数组
【 * 例 4.1.3 .2-1 】演示:用专门函数 char , str2mat , strvcat 创建多行串数组示例。 S1=char('This string array','has two rows.') S1 = This string array has two rows. S2=str2mat(' 这 ',' 字符 ',' 串数组 ',' 由 4 行组成 ') S2 = 这 字符 串数组 由4 行组成 S3=strvcat(' 这 ',' 字符 ',' 串数组 ',' ',' 由 4 行组成 ')% “空串”会产生一个空格行 S3 = 这 字符 串数组 由 4 行组成 size(S3) ans = 5 5
【 * 例 4.1.3 .2-1 】的补充
(1) 创建一个二维字符数组animal
>> Animal=[‘dog’;’monkey’];
??? Error using ==> vertcat
CAT arguments dimensions are not consistent.
>> Animal=['dog ';'monkey']; %创建成功
说明:创建二维字符数组时,字符数组要求每行字符含有相同的列。当多行字符串具有不同长度时,为了避免出现错误,用户需要在较短的字符串中添加空格,以便保证较短字符串与最长字符串等长。
(2) 用char函数创建字符数组,该方法不需要所有字符串等长
>> Animal = char(‘dog’,’monkey’);
4.1.3.3 转换函数产生数码字符串
【 * 例 4.1.3 .3-1 】最常用的数组 / 字符串转换函数 int2str , num2str , mat2str 示例。
(1) int2str 把整数数组转换成串数组(非整数将被四舍五入园整后再转换) A=eye(2,4); % 生成一个 数值数组 A_str1=int2str(A) % 转换成 串数组。请读者自己用 size 检验。 A_str1 = 1 0 0 0 0 1 0 0
(2) num2str 把非整数数组转换为串数组(常用于图形中,数据点的标识) rand('state',0) B=rand(2,4); % 生成数值矩阵 B3=num2str(B,3) % 保持 3 位有效数字,转换为串 B3 = 0.95 0.607 0.891 0.456 0.231 0.486 0.762 0.0185
(3) mat2str 把数值数组转换成输入形态的串数组(常与 eval 指令配用) B_str=mat2str(B,4) % 保持 4 位有效数字,转换为“数组输入形式”串 B_str = [0.9501 0.6068 0.8913 0.4565;0.2311 0.486 0.7621 0.0185] Expression=['exp(-',B_str,')']; % 相当于指令窗写一个表达式 exp(-B_str) eval(Expression) % 把 exp(-B_str) 送去执行 ans = 0.3867 0.5451 0.4101 0.6335 0.7937 0.6151 0.4667 0.9817
【 * 例 4.1.3 .3-2 】综合例题:在 MATLAB 计算生成的图形上标出图名和最大值点坐标。 clear % 清除内存中的所有变量 a=2; % 设置衰减系数 w=3; % 设置振荡频率 t=0:0.01:10; % 取自变量采样数组 y=exp(-a*t).*sin(w*t); % 计算函数值,产生函数数组 [y_max,i_max]=max(y); % 找最大值元素位置 t_text=['t=',num2str(t(i_max))]; % 生成最大值点的横坐标字符串 <7> y_text=['y=',num2str(y_max)]; % 生成最大值点的纵坐标字符串 <8> max_text=char('maximum',t_text,y_text);% 生成标志最大值点的字符串 <9> % 生成标志图名用的字符串 tit=['y=exp(-',num2str(a),'t)*sin(',num2str(w),'t)']; %<11> plot(t,zeros(size(t)),'k') % 画纵坐标为 0 的基准线 hold on % 保持绘制的线不被清除 plot(t,y,'b') % 用兰色画 y(t) 曲线 plot(t(i_max),y_max,'r.','MarkerSize',20) % 用大红点标最大值点 text(t(i_max)+0.3,y_max+0.05,max_text) % 在图上书写最大值点的数据值 <16> title(tit),xlabel('t'),ylabel('y'),hold off% 书写图名、横坐标名、纵坐标名

图 4.1.3 .3-1 字符串运用示意图
4.1.3.4 利用元胞数组创建复杂字符串
【 * 例 4.1.3 .4-1 】元胞数组在存放和操作字符串上的应用。 a='MATLAB 5 ';b='introduces new data types:'; % 创建单行字符串 a,b c1=' ◆ Multidimensional array';c2=' ◆ User-definable data structure'; c3=' ◆ Cell arrays';c4=' ◆ Character array'; c=char(c1,c2,c3,c4); % 创建多行字符串 c C={a;b;c}; % 利用元胞数组存放长短不同的字符串 <5> disp([C{1:2}]) % 显示前两个元胞中的字符内容 <6> disp(' ') % 显示一行空白 disp(C{3}) % 显示第 3 个元胞中的字符内容 <8> MATLAB 5 introduces new data types: ◆ Multidimensional array ◆ User-definable data structure ◆ Cell arrays ◆ Character array
4.1.4 串转换函数
【 * 例 4.1.4 -1 】 fprintf, sprintf, sscanf 的用法示例。 rand('state',0);a=rand(2,2); % 产生 随机阵 s1=num2str(a) % 把数值数组转换为串数组 s_s=sprintf('%.10e\n',a) %10 数位科学记述串 , 每写一个元素就换行。 s1 = 0.95013 0.60684 0.23114 0.48598 s_s = 9.5012928515e-001 2.3113851357e-001 6.0684258354e-001 4.8598246871e-001
fprintf('% .5g \\',a) % 以 5 位数位最短形式显示。不能赋值用 0.95013\0.23114\0.60684\0.48598\
s_sscan=sscanf(s_s,'%f',[3,2])% 浮点格式把串转换成成 数值数组。 s_sscan = 0.9501 0.4860 0.2311 0
0.6068 0
关于四分位数(Quartile)在wikipedia维基百科 上搜索英语版或者中文版都有很清晰的解释
在 wikipedia维基百科 上搜索 Box Plot :
箱形图(Box-plot)又称为盒须图、盒式图或箱线图,是一种用作显示一组数据分散情况资料的统计图。因型状如箱子而得名。在各种领域也经常被使用,常见于品质管理。不过作法相对较较繁琐。 箱形图于1977年由美国著名统计学家 John Tukey发明。它能显示出一组数据的最大值、最少值、中位数、下四分位数及上四分位数。
以下是箱形图的具体例子:
+-----+-+
* o |-------| + | |---|
+-----+-+
+---+---+---+---+---+---+---+---+---+---+ 數線
0 1 2 3 4 5 6 7 8 9 10
这组数据显示出:
- 最小值(min)=5。
- 下四分位数(Q1)=7。
- 中位数(Med)=8.5。
- 上四分位数(Q3)=9。
- 最大值(max)=10。
- 平均值=8。
- 四分位间距(interquartile range)=Q3 − Q1=2
http://www.physics.csbsju.edu/stats/box2.html
The box plot (a.k.a. box and whisker diagram) is a standardized way of displaying the distribution of data based on the five number summary: minimum, first quartile, median, third quartile, and maximum. In the simplest box plot the central rectangle spans the first quartile to the third quartile (the interquartile range or IQR). A segment inside the rectangle shows the median and "whiskers" above and below the box show the locations of the minimum and maximum.
This simplest possible box plot displays the full range of variation (from min to max), the likely range of variation (the IQR), and a typical value (the median). Not uncommonly real datasets will display surprisingly high maximums or surprisingly low minimums called outliers. John Tukey has provided a precise definition for two types of outliers:
- Outliers are either 3×IQR or more above the third quartile or 3×IQR or more below the first quartile.
- Suspected outliers are are slightly more central versions of outliers: either 1.5×IQR or more above the third quartile or 1.5×IQR or more below the first quartile.
If either type of outlier is present the whisker on the appropriate side is taken to 1.5×IQR from the quartile (the "inner fence") rather than the max or min, and individual outlying data points are displayed as unfilled circles (for suspected outliers) or filled circles (for outliers). (The "outer fence" is 3×IQR from the quartile.)
If the data happens to be normally distributed,
IQR = 1.35 σ
where σ is the population standard deviation.
Suspected outliers are not uncommon in large normally distributed datasets (say more than 100 data-points). Outliers are expected in normally distributed datasets with more than about 10,000 data-points. Here is an example of 1000 normally distributed data displayed as a box plot:
Note that outliers are not necessarily "bad" data-points; indeed they may well be the most important, most information rich, part of the dataset. Under no circumstances should they be automatically removed from the dataset. Outliers may deserve special consideration: they may be the key to the phenomenon under study or the result of human blunders.
Example A
Consider two datasets:
A1={0.22, -0.87, -2.39, -1.79, 0.37, -1.54, 1.28, -0.31, -0.74, 1.72, 0.38, -0.17, -0.62, -1.10, 0.30, 0.15, 2.30, 0.19, -0.50, -0.09}
A2={-5.13, -2.19, -2.43, -3.83, 0.50, -3.25, 4.32, 1.63, 5.18, -0.43, 7.11, 4.87, -3.10, -5.81, 3.76, 6.31, 2.58, 0.07, 5.76, 3.50}
Notice that both datasets are approximately balanced around zero; evidently the mean in both cases is "near" zero. However there is substantially more variation in A2 which ranges approximately from -6 to 6 whereas A1 ranges approximately from -2½ to 2½.
Below find box plots and the more traditional error bar plots (with 1-σ bars). Notice the difference in scales: since the box plot is displaying the full range of variation, the y-range must be expanded.
Example B
B1={1.26, 0.34, 0.70, 1.75, 50.57, 1.55, 0.08, 0.42, 0.50, 3.20, 0.15, 0.49, 0.95, 0.24, 1.37, 0.17, 6.98, 0.10, 0.94, 0.38}
B2= {2.37, 2.16, 14.82, 1.73, 41.04, 0.23, 1.32, 2.91, 39.41, 0.11, 27.44, 4.51, 0.51, 4.50, 0.18, 14.68, 4.66, 1.30, 2.06, 1.19}
Notice that the datasets span much the same range of values (from about .1 to about 50) and that all the values are positive. Most of the B1 values are less than one whereas most of the B2 values are more than one. We can use a log scale to better display this large range of values:
On the other hand, a straightforward plot of the sample means and population standard deviations, suggests negative values (which prevents use of a log-scale) and broad overlap between the two distributions. (A t-test would suggest B1 and B2 are not significantly different.)
Example C
One case of particular concern --where a box plot can be deceptive-- is when the data are distributed into "two lumps" rather than the "one lump" cases we've considered so far.
A "bee swarm" plot shows that in this dataset there are lots of data near 10 and 15 but relatively few in between. See that a box plot would not give you any evidence of this.
Matlab中有关boxplot(X)命令的解释: boxplot(X) produces a box and whisker plot for each column of the matrix X. The box has lines at the lower quartile, median, and upper quartile values. Whiskers extend from each end of the box to the adjacent values in the data—by default, the most extreme values within 1.5 times the interquartile range from the ends of the box. Outliers are data with values beyond the ends of the whiskers. Outliers are displayed with a red + sign.
格式 boxplot(X) %产生矩阵X的每一列的盒图和“须”图,“须”是从盒的尾部延伸出来,并表示盒外数据长度的线,如果“须”的外面没有数据,则在“须”的底部有一个点。 boxplot(X,notch) %当notch=1时,产生一凹盒图,notch=0时产生一矩箱图。 boxplot(X,notch,'sym') %sym表示图形符号,默认值为“+”。 boxplot(X,notch,'sym',vert) %当vert=0时,生成水平盒图,vert=1时,生成竖直盒图(默认值vert=1)。 boxplot(X,notch,'sym',vert,whis) %whis定义“须”图的长度,默认值为1.5,若whis=0则boxplot函数通过绘制sym符号图来显示盒外的所有数据值。
Examples 1
The following commands create a box plot of car mileage grouped by country.
load carsmall
boxplot(MPG,Origin)
Examples 2 The following example produces notched box plots for two groups of sample data.
x1 = normrnd(5,1,100,1);
x2 = normrnd(6,1,100,1);
boxplot([x1,x2],'notch','on')
Examples 3
x1 = normrnd(5,1,100,1); x2 = normrnd(6,1,100,1); boxplot([x1,x2])
The difference between the medians of the two groups is approximately 1.Since the notches in the boxplot do not overlap, you can conclude, with 95% confidence, that the true medians do differ.
Examples 4
The following figure shows the boxplot for same data with the length of the whiskers specified as 1.0 times the interquartile range. Points beyond the whiskers are displayed using +.
x1 = normrnd(5,1,100,1); x2 = normrnd(6,1,100,1); boxplot([x1,x2],'notch','on','whisker',1)
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Endnote里的文献类型有很多,有journal article、conference paper等。其中,关于会议的文献类型有conference proceeding和conference paper两个,这两 个有什么区别呢?
Endnote官方网站上有如下描述:
The Conference Proceedings reference type is best used for unpublished proceedings. Articles that are published as part of the comprehensive conference proceedings should be entered as Conference Paper references.
也就是说,对于一般已经出版的proceeding,应该归结到Conference Paper里面,只有没有出版的Proceeding才放到conference proceeding。
参考文献样式: (1) LNAI,LNCS是杂志,会议,会议录?怎么写参考文献格式,按照什么格式Hongqiang Wang 师兄主页书中的章还是Chunhou Zheng 师兄主页第六和第八个参考文献。如Feature extraction from tumor gene expression profiles using DCT and DFT到web of science上可以查到是个会议论文,会议名字也能查到。在Book Series: LECTURE NOTES IN ARTIFICIAL INTELLIGENCE中,Shuling Wang老师讲应该按照会议论文格式 参考文献样式: 比较好的方式:作者,“文章名,”杂志或会议名,卷号(会议地点),期号(会议时间),页码,年份。(参见March 10,2010邮件) (2)Riemannian manifold learning: 查老师这篇文章的第48篇引用文献是来自维基百科,51和52是引用的数据,值得学习这种引用方式!
    不多说了,在 金士顿DDRII 667或者DDRII 800 内存的真假辨别的这篇文章中已经说的很明白了,由于有的玩家朋友希望能拿个假货进行对比,所以这次发个全套照片供大家查看辨别.
方法:到google上搜索关键词:CVPR 2009 papers on the web NIPS ( http://books.nips.cc/) ICML ( http://www.cs.mcgill.ca/~icml2009/abstracts.html.). AAAI10: http://www.aaai.org/ocs/index.php/AAAI/AAAI10/schedConf/presentations; AAAI 12: http://www.aaai.org/ocs/index.php/AAAI/AAAI12/schedConf/presentations;AAAI短文在电脑"paper\aa_other\AAAI短文\" ICCV 2019 https://mp.weixin.qq.com/s/-l9Wyh945k3XNeHw-ApjzA http://openaccess.thecvf.com/ICCV2019.py
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