粘贴函数中的R闪亮传递列名称

Question

I am working on a shiny app, where i need to pass the column names through selectInput. However when i pass the variable name to a paste function it is considering as text instead of a variable/column name.

lets say i have dataframe ie df3

df3 <- data.frame(a=c(1:10),b=c(1:10),c=c(1:10),d=c(1:10),e=c(1:10),f=c(1:10),g=c(1:10))

ID  a  b  c  d  e  f  g
1   1  1  1  1  1  1  1
2   2  2  2  2  2  2  2
3   3  3  3  3  3  3  3

using selectInput i will pass the columns e , f, g dynamically based on my requirement

selectInput("columns1","Select the 1st Filter Variable:", choices = colnames)}})

df3$concate1 <- with(df3, (paste0(a,'+',b,'+',c,'+',input$columns1))

when i pass the variable 'e' the variable name is substituted but not the values in column 'e' ie

ID concate1
1  1+1+1+e
2  2+2+2+e
3  3+3+3+e

I need to get the values of column 'e' in the df3$concate1 in the below manner. plz help me in resolving this.

ID concate1
1  1+1+1+1
2  2+2+2+2
3  3+3+3+3

Answer 1

library(shinydashboard)
library(shiny)

df3 <- data.frame(a=c(1:10),b=c(1:10),c=c(1:10),d=c(1:10),e=c(1:10),f=c(1:10),g=c(1:10))


ui <-  shinyUI(fluidPage(mainPanel(
  selectInput("columns1","Select the 1st Filter Variable:", colnames(df3),colnames(df3[1])),
  textOutput("selection")
)
)
)


server <- function(input, output){  

  output$selection <- renderText({
    column = (input$columns1);
    columnElement = which(colnames(df3) == column)
    df3$concate1 <- with(df3, (paste0(a,'+',b,'+',c,'+',columnElement)))
  })


}