Sometimes data needs to be converted from a continuous range, like test scores, to a discrete set of output values, like letter grades. In this lesson we’ll see how to use d3.scaleQuantize() to do exactly that. function scaleQuantize(){ var quantizeS…

When your data contains discrete, non-numeric property values that you need to format or convert before displaying, d3.scaleOrdinal() is the API you need. Maybe you need to convert a “pass”/”fail” field to “green”/”red” for coloring your bubble chart…

Mapping abstract values to visual representations is what data visualization is all about, and that’s exactly what D3 scales do. This is usually done using pretty straightforward algorithms, but nothing is straightforward when you’re working with Dat…

Tushare返回的是pandas的DataFrame格式,但是执行以下代码时报错:TypeError: Empty 'DataFrame': no numeric data to plot import tushare as ts df_all = ts.realtime_boxoffice() df_box_office = df['BoxOffice'] df_box_office.index = df['Irank'] df_box_office.plot(kind='bar') 反复输…

数据可视化 在可视化工作中,一个基本出发点是将不同的数值映射到不同的可视化 元素的属性上,使其表现出各自不同的视觉特征. 比如:以数组中的每一个值为直径分别创建一个圆,我们得到三个圆: 在d3中,可视化元素可以是HTML元素或者SVG元素.比如,我们可以使用一个圆角的 DIV元素表示圆.这样一个数字就对应了一个DIV元素. data:数据操作符 在d3的处理流水线中,data()操作符使用数据来修剪选择集中的DOM元素: 选择集的data()操作符执行后返回的是一个新的选择集,其内容是与数据集…

Change is good, but creating from scratch is even better. This lesson shows you how to create DOM elements from D3 and insert them into your document as needed. You’ll officially be on your way to creating data visualizations! d3.select('.title') .in…

Sql语句分为三大类: 数据定义语言,负责创建,修改,删除表,索引和视图等对象: 数据操作语言,负责数据库中数据的插入,查询,删除等操作: 数据控制语言,用来授予和撤销用户权限. 数据定义语言 (Data Definition Language, DDL) 是SQL语言集中负责数据结构定义与数据库对象定义的语言,由CREATE.ALTER与DROP三个语法所组成,最早是由 Codasyl (Conference on Data Systems Languages) 数据模型开始,现在被纳入 SQ…

1. Set password for SYS in password file: orapwd file=$ORACLE_HOME/dbs/orapw<ORACLE_SID> 2. Drop repos data copied from the original database ( you may need to unlock sysman user first ): emca -deconfig dbcontrol db -repos drop 3. If emca cannot dro…

Most charts aren’t complete without axes to provide context and labeling for the graphical elements being displayed. This lesson introduces D3’s APIs for creating, customizing, and displaying axes while building on topics from previous lessons. var m…

Mapping abstract values to visual representations is what data visualization is all about, and that’s exactly what D3 scales do. Turning a test score into a column height, or a percentage into an opacity requires translating from one set of possible…