有关重命名功能的问题

如何解决有关重命名功能的问题

我正在编写一些代码来计算函数的派生类。我设法为1个变量生成一阶和二阶导数，并作为函数存储在环境中，因此以后可以对其进行绘制。现在，我正在尝试计算具有2个或更多变量的方程的偏导数，而我找不到能够在环境中生成与该函数的偏导数一样多的代码。

为了澄清，我使用了1个变量：

    f <- function(x) cos(20*x)*exp(-1*x)
    F.<- function (x) eval(D(as.expression(body(f)),"x"))
    F..<- function (x) eval(D(as.expression(D(as.expression(body(f)),"x")),"x"))

并且运行良好，我在环境中获得了3个功能：

functions

但是对于多个变量，我必须遍历此函数并生成与方程的偏导数一样多的函数。

我的问题是：如何生成一个循环，以计算函数的偏导数并将其存储为函数，每个都有一个自定义名称？

我在for循环中尝试了导数函数，但无法为每次导数计算定义不同的名称：

    for (i in 1:nro_variables) {
      var_D = vector_variables[i]  
      F.<- function (x) eval(D(as.expression(body(f)),var_D))
    }

解决方法

类似于避免使用分配许多单独的相似对象来泛滥全局环境的方法，请考虑使用可以为元素建立索引的单个列表，以更好地进行串行组织。请参阅@GregorThomas的最佳做法answer，主张：

永远不要首先创建d1 d2 d3，...，dn。创建包含d个元素的列表n。

具体来说，如果vector_variables是字符向量，则sapply使用simplify=FALSE将返回函数的命名列表。是的，仍然可以调用列表中的函数。

partial_deriv_funcs <- sapply(vector_variables,function(var_D) {
    f <- function(x) cos(20*x)*exp(-1*x)
    return(function(x) eval(D(as.expression(body(f)),var_D)))
},simplify = FALSE)

单个或迭代地调用函数元素：

# CALL SINGLE FUNCTION WITH SINGLE PARAM
result <- partial_deriv_funcs[['var1']](param)

# CALL SAME FUNCTION WITH VECTOR OF PARAMS
results <- lapply(param_vector,partial_deriv_funcs[['var1']])

# CALL ALL FUNCTIONS USING SAME PARAM
results <- lapply(partial_deriv_funcs,function(f) f(param))

# CALL ALL FUNCTIONS EACH WITH DIFFERENT PARAM
results <- mapply(function(f,p) f(p),partial_deriv_funcs,param_per_func_vector,SIMPLIFY= FALSE)
results <- Map(function(f,param_per_func_vector) # EQUIVALENT

vocations.json和[ "Accessory designer","Acoustical engineer","Acrobat","Actor","Actress","Advertising designer","Aeronautical engineer","Aerospace engineer","Agricultural engineer","Anesthesiologist","Anesthesiologist Assistant","Animator","Anthropologist","Applied engineer","Arborist","Archaeologist","Archimime","Architect","Army officer","Art administrator","Artisan",[...] ]可用于定义函数，而<!DOCTYPE html> <html lang = "en"> <head> <meta charset = "UTF-8"> <title>testform</title> <link rel = "stylesheet" href = "test2.css"> <style> .enrol_class { display: flex; flex-direction: row,align-items: center} </style> </head> <body> <div class='enrol_class'> <ul> <li> <input type = "radio" id = "rad_1" name = "classes" class = "radio_btn"> <label for="rad_1">Class 1</label> </li> <li> <input type = "radio" id = "rad_2" name = "classes" class = "radio_btn"> <label for="rad_2">Class 2</label> </li> <li> <input type = "radio" id = "rad_3" name = "classes" class = "radio_btn"> <label for="rad_3">Class 3</label> </li> </ul> <button type = "button" id = "enrol_btn" style='margin-left: 20px'>ENROL</button> </div> </body>可为其指定正确的名称。

eval