CODEWITHSUNDEEP
rggplot2data-visualizationmedian
Tony Flager
Tony Flager

Reputation: 95

Plot the Average Value of a Variable using ggplot2

I have two columns that I would like to plot in a bar chart: "Property_type" and "Price". Using the code below, I will plot the "total price" instead of the "median price" for each property type. Could you help me fix the code? 

theme_set(theme_bw())

# Draw plot
ggplot(data, aes(x=Property_type, y=Price)) + 
  geom_bar(stat="identity", width=.5, fill="tomato3") + 
  labs(title="Ordered Bar Chart", 
       subtitle="Average Price by each Property Type", 
       caption="Image: 5") + 
  theme(axis.text.x = element_text(angle=65, vjust=0.6))

Image Here

Upvotes: 1

Views: 2354

Answers (2)

dc37
dc37

Reputation: 16178

Using dplyr, you can calculate the median price for each property and then pass this new variable as y value in ggplot2:

library(dplyr)
library(ggplot2)

data %>% 
  group_by(Property) %>% 
  summarise(MedPrice = median(Price, na.rm = TRUE)) %>%
  ggplot(aes(x = reorder(Property,-MedPrice), y = MedPrice)) +
  geom_col(fill = "tomato3", width = 0.5)+
  labs(title="Ordered Bar Chart", 
       subtitle="Average Price by each Property Type", 
       caption="Image: 5") + 
  theme(axis.text.x = element_text(angle=65, vjust=0.6))

Does it answer your question ?

If not, please provide a reproducible example of your dataset by following this guide: How to make a great R reproducible example

Upvotes: 1

teunbrand
teunbrand

Reputation: 37953

While dc37's answer will get you what you want perfectly, I just wanted to point out that you could also use the stat_* family of functions within ggplot to calculate groupwise summary statistics.

library(ggplot2)

df <- data.frame(
  Property = rep(LETTERS[1:10], each = 10),
  Price = rnorm(100, rep(1:10, each = 10))
)

ggplot(df, aes(Property, Price)) +
  stat_summary(fun = median, geom = "col")

Created on 2020-04-18 by the reprex package (v0.3.0)

Upvotes: 1

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