在R中绘制一个函数，保持所有变量不变，除了一个

Question

我如何绘制一个保持一个变量常量的函数？

我想从y轴上的函数和x轴上的利率绘制“monthPay”。所有变量都将保持不变。

我相信有一个功能可以做到这一点，但我不记得它的名字。

mortgage <- function(P=500000, I=6, L=30) { 
J <- I/(12 * 100)
N <- 12 * L
M <- P*J/(1-(1+J)^(-N))
monthPay <- M

# Calculate Amortization for each Month
    Pt <- P # current principal or amount of the loan
    currP <- NULL
    while(Pt>=0) {
        H <- Pt * J # this is the current monthly interest
        C <- M - H # this is your monthly payment minus your monthly interest, so it is the amount of principal you pay for that month
        Q <- Pt - C # this is the new balance of your principal of your loan
        Pt <- Q # sets P equal to Q and goes back to step 1. The loop continues until the value Q (and hence P) goes to zero
        currP <- c(currP, Pt)
    }#End Pt Calc

    monthP <- c(P, currP[1:(length(currP)-1)])-currP
    aDFmonth <<- data.frame(
                      Amortization=c(P, currP[1:(length(currP)-1)]), 
                      Monthly_Payment=monthP+c((monthPay-monthP)[1:(length(monthP)-1)],0),
                      Monthly_Principal=monthP, 
                      Monthly_Interest=c((monthPay-monthP)[1:(length(monthP)-1)],0), 
                      Year=sort(rep(1:ceiling(N/12), 12))[1:length(monthP)]
            )#end aDFmonth 
    aDFyear <- data.frame(
                     Amortization=tapply(aDFmonth$Amortization, aDFmonth$Year, max), 
                     Annual_Payment=tapply(aDFmonth$Monthly_Payment, aDFmonth$Year, sum), 
                     Annual_Principal=tapply(aDFmonth$Monthly_Principal, aDFmonth$Year, sum), 
                     Annual_Interest=tapply(aDFmonth$Monthly_Interest, aDFmonth$Year, sum), 
                     Year=as.vector(na.omit(unique(aDFmonth$Year)))
                     )#end aDFyear 

  return(list(monthPay, aDFmonth,aDFyear ))
}


temp<-mortgage(P=500000, I=6, L=30)
temp[[1]] #the var. for the y-axis.