Arranging x-axis in ggplot

[chitemerere]

I have the following ggplot output in a Shiny App:

The plot Months on the x-axis are arranged in alphabetical order and the following code is used to render the plots:

  ## Graph of transactions per month
  output$TransMonthPlot <- renderPlot({
    req(credentials()$user_auth)
    withProgress(message = 'Calculation in progress',
                 detail = 'This may take a while...', value = 0, {
                   for (i in 1:15) {
                     incProgress(1/15)
                     Sys.sleep(15)
                   }
                   
                 })
    
    g1 <-  MBA_Online() %>%
      
      filter(transDate >= input$dRange[1] & transDate <= input$dRange[2]) %>%
      dplyr::group_by(Month) %>%
      dplyr::summarize(Transactions = n_distinct(Transaction)) %>%
      ggplot(aes(x=Month, y = Transactions, fill = Month)) +
      geom_bar(stat="identity") +
      geom_label(aes(label= format(Transactions, big.mark = ",")))+
      theme(legend.position="none")+
      theme(panel.background = element_blank())+
      labs(x = "Month", y = "Transactions", title = "Transactions per month")
    
    ## Plot items per transaction per month
    x1 <-  MBA_Online() %>%
      
      filter(transDate >= input$dRange[1] & transDate <= input$dRange[2]) %>%
      group_by(Month) %>% 
      dplyr::summarise(Count = n()) 
      
    x2 <- MBA_Online() %>%
     
      filter(transDate >= input$dRange[1] & transDate <= input$dRange[2]) %>%
      group_by(Month, Transaction) %>%
      dplyr::summarise(n_distinct(Transaction)) %>%
      dplyr::summarise(Count =n())
      
    x3 <- data.frame(x1, x2[2], x1[2]/x2[2])
    
    colnames(x3) <- c("Month", "Line", "Unique", "Items.Trans")
    
    g2 <- ggplot(x3,aes(x=Month, y = Items.Trans, fill=Month))+
      theme_fivethirtyeight()+
      geom_bar(stat = "identity")+
      theme(legend.position = "none")+
      geom_text(aes(label=round(Items.Trans,0)), vjust=2) +
      labs(
        x="Month",
        y="Items",
        title = paste(
          "Items per transaction per Month"
        )
      )
    
    grid.arrange(g1,g2)
    
  }, height = 600, width = 800)

How can i arrange the x-axis in order of rising month starting with January, February, March ... to December?

How can i also arrange the x-axis to show the plots either in ascending or descending order to the y-axis value?

[FJCC]

library(ggplot2)
library(dplyr)
#Ordered by ggplot
df <- data.frame(Month = c("December", "January", "November", "February", "October", 
                           "March", "September", "April", "August", "May", "July", "June"),
                 Value = 1:12, stringsAsFactors = FALSE)
ggplot(df, aes(Month, Value)) + geom_col()

#Ordered by Value
Ordered <- df[order(-df$Value), "Month"]
df2 <- df %>% mutate(Month = factor(Month, levels = Ordered, ordered = TRUE))
ggplot(df2, aes(Month, Value)) + geom_col()

#Ordered by Month
df3 <- df %>% mutate(Month = factor(Month, 
                    levels = c("January", "February", "March", "April", 
                               "May", "June", "July", "August", 
                               "September", "October", "November", "December"),
                    ordered = TRUE))
ggplot(df3, aes(Month, Value)) + geom_col()

^{Created on 2019-07-16 by the reprex package (v0.2.1)}

[chitemerere]

Thank you very much for your input, most appreciated