评估 R 循环中的变量 [英] Evaluating variable within R loop

问题描述

我正在尝试使用 For 循环迭代生成一些函数:

I'm trying to iteratively generate some functions using a For Loop:

# Create a list to hold the functions
funcs <- list()
funcs[]

# loop through to define functions
for(i in 1:21){

    # Make function name
    funcName <- paste( 'func', i, sep = '' )

    # make function
    func = function(x){x * i}

    funcs[[funcName]] = func

    }

然而，它并没有像我希望的那样工作，因为没有在每个函数中评估 i 值.我想尝试将函数定义为等于 x * 1；x * 2;等等，但我最终得到的是一个 x * i 的函数；其中 i 是 21.

However, it's not working as I hoped as the i value is not being evaluated within each function. I want to try and define the function to equal x * 1; x * 2; etc, but what I end up with is a function that is x * i; where i is 21.

我尝试使用 eval() 函数，结果只是存储了 x * eval(i).

I tried using the eval() function and that just resulted in x * eval(i) being stored.

推荐答案

检查这个:

# Create a list to hold the functions
funcs <- list()
funcs[]

# loop through to define functions
for(i in 1:21){

    # Make function name
    funcName <- paste( 'func', i, sep = '' )

    # make function
    func = paste('function(x){x * ', i,'}',sep = '')

    funcs[[funcName]] = eval(parse(text=func))

    }

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