什么是ces效用函数

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什么是ces效用函数,第1张

效用函数通常是用来表示消费者在消费中所获得的效用与所消费的商品组合之间数量关系的函数，以衡量消费者从消费既定的商品组合中所获得满足的程度。

效用函数的定义是设f是定义在消费集合X上的偏好关系,如果对于X中任何的x,y,xfy当且仅当u(x)≥u(y),则称函数u:X→R是表示偏好关系f的效用函数。

corners = par("usr") #获取plot区域4个角的坐标点 (x1, x2, y1, y2)

text(x = corners[2]-0.2, y = mean(corners[3:4]), "CESD", srt = 270)

R objects that reside in other R objects can require a lot of typing to access. For example, to refer to a variable x in a dataframe df , one could type df$x . This is no problem when the dataframe and variable names are short, but can become burdensome when longer names or repeated references are required, or objects in complicated structures must be accessed. The attach() function in R can be used to make objects within dataframes accessible in R with fewer keystrokes. As an example: ... then detach() the dataset to clean up after ourselves. 之后，用命令 detach（） 结束使用数据集。 users are cautioned that if there is already a variable called cesd in the local workspace, issuing attach(ds) , may not mean that cesd references ds$cesd . Name conflicts of this type are a common problem with attach() and care should be taken to avoid them. The help page for attach() notes that attach can lead to confusion . The Google R Style Manual provides clear advice on this point, providing the following advice about attach() : The possibilities for creating errors when using attach are numerous. Avoid it.So what options exist for those who decide to go cold turkey? 那么，有哪些应对方法呢？ (Also note the within() function, which is similar to with() , but returns a modified object.) Some examples may be helpful： 比如下面这个例子： In short, there’s never an actual need to use attach() , using it can lead to confusion or errors, and alternatives exists that avoid the problems. We recommend against it. 详细语法可以在R中输入 ??with 查看。 文献参考： https://www.r-bloggers.com/to-attach-or-not-attach-that-is-the-question/