R 中使用 rSymph

如何解决R 中使用 rSymph

我需要在 R 控制台中使用 rSympy 执行符号矩阵乘法 Ry.Ry。

library(rSymPy)
Ry = matrix(c("c","-s","s","c"),2,byrow=1); Ry
########## I convert matrix in R to Python's format
# from https://stackoverflow.com/questions/39820161/handling-symbolic-matrices-in-r-as-in-matlab
# written by jav

mat2py <- function(x){
  str = lapply(1:nrow(x),function(i) 
paste0(x[i,],collapse = ","))
  str = paste0("Matrix([",paste0("[",unlist(str),"]","),"])")
  return (str)
}
mat2py(Ry)
cat(sympy(mat2py(Ry)),"\n")    

得到如下错误信息：

.jcall 中的错误("RJavaTools","Ljava/lang/Object;","invokeMethod",cl,: 回溯（最近一次调用最后一次）：文件“”，行 1、在NameError: name 'c' is not defined

解决方法

仍然收到错误消息。当我执行 cat(sympy("Ry*Ry"),"\n")

.jcall("RJavaTools","Z","hasField",.jcast(x,"java/lang/Object") 中的错误，： java.lang.NullPointerException #################### 下面是代码#############

library(rSymPy)
str1="c"
str2="-s"
str3="s"
str4="c"
str(str1)
P=matrix(c(str1,str2,str3,str4),2,byrow=1); P

Ry<-matrix(nrow=2,ncol=2)
for (i in 1:2){
for (j in 1:2) {
Ry[i,j] = paste0(P[i,j]) # Declare variable in matrix 
first
   }
 }
Ry

mat2py <- function(x){
str = lapply(1:nrow(x),function(i) paste0(x[i,],collapse = ","))
str = paste0("Matrix([",paste0("[",unlist(str),"]","),"])")
return (str)
}

 mat2py(Ry)
 cat(sympy(mat2py(Ry)),"\n")
 cat(sympy("Ry*Ry"),"\n")

,

遵循 rSymPy 的文档 - 您是否已经尝试使用此代码？ 我不熟悉 rSymPy 包，但我认为有必要将您的变量 c、-s 和 s 声明为 SymPy 变量。

library(rSymPy)
# create a SymPy variable called c
sympy("var('c')")
# create a SymPy variable called -s
sympy("var('-s')")
# create a SymPy variable called s
sympy("var('s')")

# Matrices are stored row by row (unlike R matrices)
cat(sympy("Ry = Matrix([[c,-s],[s,c]])"),"\n")
cat(sympy("Ry*Ry"),"\n")