How do i fix error: data.frame: replacement has 148 rows, data has 1 (shiny and R)

Question

I'm new to R and I'm trying to make my chart interactive using shiny and leaflet in R. however I can't seem to run my map_data() under reactive ({ code }) because I receive an error that says:

Warning: Error in $<-.data.frame: replacement has 148 rows, data has 1

I tried creating a new variable but it resulted in the samed thing. I stumbled upon similar solutions but I didn't exactly understand how to go about it.

This is my code overall:

library(janitor)
library(leaflet)
library(dplyr)
library(sp)
library(shiny)

climate <- read.csv("globalcrops.csv")
View(climate)

coordinates <- read.csv("worldcoord.csv")
View(coordinates)

#cleaning the data
climate <- climate %>%
  janitor::clean_names()#clean names

#selecting specific columns 
#removing missing values with na.omit
df3 <- climate[, c("i_country", "act_ch_wha1f2050", "act_ch_mza1f2050", "act_ch_ria1f2050")] %>%
  na.omit(df)

df3

#combine tables together
#new data frame df3
df4 = merge(x=df3, y=coordinates, by="i_country")
df4

#changing data of latitude and longitude into numerical value 
df4$latitude <- as.numeric(df4$latitude)
df4$longitude <- as.numeric(df4$longitude)

#creating a new spatial point data frame 
#to echo spatial point data frame  there
#for mapping
# - 
#getting spatial data from columns 5 and 6
#the
df4.SP <- SpatialPointsDataFrame(df4[,c(5,6)], df4[,-c(5,6)])

# change colors
countCol <- colorFactor(palette = 'RdYlGn', df4$i_country)

#plotting the map using leaflet
print (
  m2 <- leaflet() %>%
  addProviderTiles("Esri.WorldGrayCanvas") %>%
  addCircles(data = df4, lng = ~longitude, lat = ~latitude, 
             popup = paste("Country:", df4$i_country, "<br>",
                           "Wheat Total Production Changes:", df4$act_ch_wha1f2050, "<br>",
                           "Maize Total Production Changes:", df4$act_ch_mza1f2050, "<br>",
                           "Rice Total Production Changes:", df4$act_ch_ria1f2050),
             color = ~countCol(i_country)
             )
)

ui <- fluidPage(
  titlePanel("Wheat, Maize and Rice Total Production Changes in 2050 Applying the SRES A1F2050 Scenario Yield Change to 1990 Production"),
    sidebarPanel (
      uiOutput("countrynames")
      #helpText("Production Changes of Staple Crops in Various Countries"),
      #selectInput(inputId = "var",
      #            label = "Choose a Location",
      #            choices = c ("Andorra",
      #                         "United Arab Emirates"),
      #            selected = "Andora"),
        
      ),
    leafletOutput("mymap")
    
)
server <- function(input, output, session){
  output$countrynames <- renderUI({
    helpText("Production Changes of Staple Crops in Various Countries")
    selectInput(inputId = "i_country",
                label = "Select a country",
                c(as.character(df4$i_country)))
  })
  
  map_data <- reactive({
    data <- data.frame(df4[df4$i_country == input$i_country,])
    data$popup <- paste0("Country:", df4$i_country, "<br>",
                         "Wheat Total Production Changes:", df4$act_ch_wha1f2050, "<br>",
                         "Maize Total Production Changes:", df4$act_ch_mza1f2050, "<br>",
                         "Rice Total Production Changes:", df4$act_ch_ria1f2050)
    return(data)
  })
  
  output$mymap <- renderLeaflet({
    m2 <- leaflet(data = map_data()) %>%
      addProviderTiles("Esri.WorldGrayCanvas") %>%
      addCircles(lng = ~longitude, lat = ~latitude, popup = ~popup,
                   #paste("Country:", df4$i_country, "<br>",
                    #            "Wheat Total Production Changes:", df4$act_ch_wha1f2050, "<br>",
                     #          "Maize Total Production Changes:", df4$act_ch_mza1f2050, "<br>",
                      #         "Rice Total Production Changes:", df4$act_ch_ria1f2050),
                 color = ~countCol(i_country)
      )
    
  })
  

}

shinyApp(ui, server)

Any help will be great! Thanks

Answer 1

Problem is probably here:

  map_data <- reactive({
    data <- data.frame(df4[df4$i_country == input$i_country,])
    # you filtered data to one row but you used df4 below
    data$popup <- paste0("Country:", data$i_country, "<br>",
                         "Wheat Total Production Changes:", data$act_ch_wha1f2050, "<br>",
                         "Maize Total Production Changes:", data$act_ch_mza1f2050, "<br>",
                         "Rice Total Production Changes:", data$act_ch_ria1f2050)
    return(data)
  })