在R中的多个列上进行季节性分解

Question

I am learning to code in R and have been strugling to get something very simple to work. I have a database with prices of products, each column represents the time series of a product. I want to run a Seasonal Decomposition of Time Series on each column and get the results in a list separated by product name.

When I run the code below I get the error:

Error in assign(paste(j), x[j]) <- (stl(dados_resumo[, x], s.window = "periodic")) : could not find function "assign<-"

for (i in 1:3)
{
    x <- (i)
    for(j in colnames(df)){
    assign(paste(j), x[j]) <- (stl(df[,x], s.window="periodic"))
    }
} 

Answer 1

I'm not sure what your data frame looks like, so I'll have a go at this manually.

Firstly, assign isn't a function, which is exactly what the error is telling you.

for( i in 1:length( df ) )
{
   df$stl[i] <- stl( df[,i], s.window = "periodic" )
}

Answer 2

'assign<-' is not a function, however, 'assign' is; which is used in the form of assign(varname,varvalue,environment) for example, if you want to assign value "bigworld" to varible named x in global environment you can use

assign(x,"bigworld",envir=.GlobalEnv)

envir can be set as envir = .GlobalEnv so that even in a function deep in stack or calling chain, you can assign value to var in global environment

the equation

 x = a 

or

 x <- a

can also be used for assigning but inside the function, this will not affect the value globally, once the function is returned, x is removed