setNames(c("#a6dba0", "#c2a5cf", "#762a83"), c("depleted", "maintained", "enriched"))
时间: 2023-12-11 08:32:40 浏览: 30
这是一个R语言的函数,其作用是将颜色向量和名称向量作为输入,返回一个命名的颜色向量。具体实现如下:
```R
setNames(c("#a6dba0", "#c2a5cf", "#762a83"), c("depleted", "maintained", "enriched"))
```
其中,`c("#a6dba0", "#c2a5cf", "#762a83")`是颜色向量,`c("depleted", "maintained", "enriched")`是名称向量。函数的返回值是一个命名的颜色向量,其中每个元素都对应一个名称。在这个例子中,返回的命名颜色向量如下:
```
depleted maintained enriched
"#a6dba0" "#c2a5cf" "#762a83"
```
相关问题
Develop and analyze a mathematical model that will assist negotiators to respond to a fixed set of water supply and demand conditions. Use the model to inform dam operations: When the water level in Lake Mead is M and the water level in Lake Powell is P, how much water should be drawn from each lake to meet stated demands? If no additional water is supplied (from rainfall, etc.), and considering the demands as fixed, how long will it take before the demands are not met? How much additional water must be supplied over time to ensure that these fixed demands are met?
Mathematical models can be useful tools in analyzing water supply and demand conditions and making decisions about dam operations. One approach to modeling this situation is to use a linear programming model that maximizes the amount of water supplied while meeting the fixed demand constraints. The objective function is to maximize the total amount of water supplied, and the constraints are the demand requirements and the availability of water in Lake Mead and Lake Powell.
Given the water level in Lake Mead (M) and Lake Powell (P), let x and y be the amounts of water drawn from Lake Mead and Lake Powell, respectively. The objective function can be written as:
Maximize: x + y
Subject to:
x + y >= D (where D is the total fixed demand for water)
x <= M (the amount of water available in Lake Mead)
y <= P (the amount of water available in Lake Powell)
x, y >= 0 (non-negativity constraints)
The solution to this linear programming model will give the optimal amounts of water to be drawn from each lake to meet the fixed demand.
If no additional water is supplied and the demands are fixed, it will take until the water in either Lake Mead or Lake Powell is depleted, or both, until the demands are not met. At that point, the optimization model will not have a feasible solution, and additional water must be supplied to meet the demand.
To determine the amount of additional water that must be supplied over time, the water levels in both lakes must be modeled over time, including inputs such as rainfall and evaporation. The model can then be used to determine the minimum amount of additional water that must be supplied each year to ensure that the fixed demands are met in the future.
This is just one possible approach to modeling this situation, and there may be other models that could also be used to assist negotiators in responding to water supply and demand conditions.
Public goods: rivalry and excludability
Public goods are goods or services that are non-excludable and non-rivalrous in nature. Non-excludability refers to the fact that it is difficult or impossible to exclude someone from using the good or service once it has been provided. Non-rivalry means that consumption of the good or service by one person does not reduce the amount available for others.
However, there are two different types of public goods. The first type is non-excludable but rivalrous, such as a fishery. If too many people fish in the same area, the resource becomes depleted, making it less available to others. The second type is both non-excludable and non-rivalrous, such as air or national defense. The use of these goods or services by one person does not impact their availability to others, and it is difficult or impossible to exclude someone from using them.
In summary, the two key characteristics of public goods are non-excludability and non-rivalry, but there are different types of public goods that may have some degree of rivalry or exclusivity.
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