迹 忆

这周终于完成了R programming week 2 的作业
真的是太不容易

调试了各种BUG

list.files() 遍历路径下的所有文件，full.names=TRUE 返回带路径的文件名称

data.frame（）是一个很神奇的函数

dat<-data.frame() dat[[pollutant]] = dat[,pollutant] Github 可以参考

心血来潮，其实也不算心血来潮了，应该是蓄谋已久
终须开始学了R了，本来应该在4年以前就应该好好学习的，可是因为自己的懒惰，到现在才开始学习。

1.对于矩阵中的两个列做筛选
方法一：k<-n[n$Ozone>31&n$Temp>90,]
方法二：sub<-subset(n,"Ozone">30 & “Temp”>90)

2.取矩阵的最后几行
tail(n)

3.快速输入变量
my_div

my TAB 键 会显现候选项

To be continued

1.What is Gantt Chart

A Gantt chart is a type of bar chart that illustrates a project schedule. Gantt charts illustrate the start and finish dates of the terminal elements and summary elements of a project. Terminal elements and summary elements comprise the work breakdown structure of the project.
( from Wikipedia)

2.How to make a Gantt Chart

There are several steps to established the chart.
1). List all the activities involved in the project. Including the title and the time(starting point and the finishing deadline)

2).Establish all relationship between the activities. Such as activity A depends on activity B, which means A can start up only after the completment of B.

3).Add the time point of the activity at the related node, which can express the startup time, finish time, and the time span.

4).Mark up the essential activity of the project.

5).Arrange the executive person of the related part.

6).Adjust the chart according to the assessment of the work.

Here is an example of Gantt Chart