Hello, I have a problem when I try to creating heatmap. It just won't show

Question

I try to create heatmap in R using ggplot where I want the X-axis to be the date and Y-axis to be the return. I exported a stock data using quantmod and I calculated the daily returns. This is my code:

library(quantmod)
library(zoo)
library(ggplot2)
library(dplyr)

test1=getSymbols("BTC-USD",auto.assign=F)
test2=dailyReturn(test1)
test2=test2%>%fortify.zoo()%>%mutate(dr=daily.returns*100)
fig1=ggplot(data=test2,aes(x=Index,y=dr,fill=dr))+geom_tile()

When I run the code above, it returned an empty plot like this

Now, what I'm expecting is a plot like this.

Where the X-axis is the date and the Y-axis is the returns. The Y-axis should be from -1.5 to 1.5. Is there any way to make heatmap with only 2 values (the date and the returns)?

Answer 1

I think you are far away from your goal: Here is a starting point: Note these are only data for 10 days and you have over 3000 days!

library(quantmod)
library(zoo)
library(ggplot2)
library(dplyr)

test1=getSymbols("BTC-USD",auto.assign=F)
test2=dailyReturn(test1)
test3 <- test2%>%
    fortify.zoo()%>%
    mutate(dr=daily.returns*100)


test4 <- test3 %>% 
  slice(1:10) %>% 
  mutate(new = rep(1, 10))

  
  # Create plot
  ggplot(test4, aes(Index, new, fill = dr)) +
    geom_tile(color = "black", height = 1.6, width = 0.8) +
    scale_fill_gradient(low = "white", high = "red") +
    theme_void() +
    ylim(-2,2)+
    theme(axis.text.x = element_text(angle = 45, hjust = 1))+
    geom_text(aes(label = round(dr,1)), size = 3, color = "black")+
    scale_x_continuous(breaks = test4$Index, labels = format(test4$Index, "%Y-%m-%d"), 
                       expand = c(0.05, 0)) +
    theme(legend.position = "none",
          axis.ticks.x = element_blank(),
          axis.text.x = element_text(angle = 45, hjust = 1, vjust = 1),
          plot.margin = unit(c(8,0.5,1,1), "cm")) +
    ggtitle("dr by date")