How to annotate a boxplot in ggplot2

Problem

We want to annotate a boxplot in ggplot2. In our example we will add Tukey's five number summary (minimum, lower-hinge, median, upper-hinge, and maximum).

fivenum(iris$Sepal.Width)

[1] 2.0 2.8 3.0 3.3 4.4

library(ggplot2)
ggplot(iris, aes(factor(0), Sepal.Width)) + 
geom_boxplot() + xlab("") + scale_x_discrete(breaks = NULL)

Solution

We store Tukey's five number summary as a data frame, and then pass it as the argument data inside geom_text to add text to the plot.

five <- data.frame(x = rep(1, 5), five = fivenum(iris$Sepal.Width))
ggplot(iris, aes(x = 0, y = Sepal.Width)) + 
  geom_boxplot() + xlab("") + scale_x_discrete(breaks = NULL) + 
  geom_text(data = five, aes(x = 0, y = five, label = five), nudge_x = 0.5)

References

• geom_text
• geom_boxplot

Return the sum of multiple columns with SUMPRODUCT

Problem

For a given lookup value we want to return the sum of multiple columns. In our table, for Year 1 we'd like to return the sum of January, February, April, and December.

Solution

1. We use the function SUMPRODUCT with multiple AND (asterisk: *) and OR (plus: +) criteria.

=SUMPRODUCT((B2:M4)*(A2:A4=B7)*
      ((B1:M1=B8)+(B1:M1=B9)+(B1:M1=B10)+(B1:M1=B11)))

First we pass the range we want to sum (B2:M4), and then add the conditions: 1) Year 1 (A2:A4=B7); and 2) Months to sum: ((B1:M1=B8)+(B1:M1=B9)+(B1:M1=B10)+(B1:M1=B11))). In English, the year must be equal to Year 1 and the months must be January or February or April or December.

Related posts

• Return the sum of multiple columns with VLOOKUP

Return the sum of multiple columns with VLOOKUP

Problem

For a given lookup value we want to return the sum of multiple columns. In our table, for Year 1 we'd like to return the sum of January, February, April, and December.

Solution

1. With VLOOKUP we pass within the third argument col_index_num the array of columns we'd like to sum: {2,3,5,13}, always enclosed in curly brackets. This will return an array of 4 values {98,52,75,60}. :


{=VLOOKUP(B7,A1:M4,{2,3,5,13},0)}

2. To sum the elements of the array, we use the function sum and then press CTRL + SHIFT + ENTER or we can use the function SUMPRODUCT that doesn't require CTRL + SHIFT + ENTER.

{=SUM(VLOOKUP(B7,A1:M4,{2,3,5,13},0))}
=SUMPRODUCT(VLOOKUP(B7,A1:M4,{2,3,5,13},0))

3. An different approach would be to use SUMPRODUCT with multiple OR criteria described in this post.

Related posts

• Return the sum of multiple columns with SUMPRODUCT

How to rename suffixes when joining tables in dplyr

Problem

When joining two tables with dplyr, the suffixes .x and .y will be added to the non-joined duplicate variables to disambiguate them. In our example, to the column mpg: mpg.x y mpg.y. How can override these suffixes?

library(dplyr) 
left_join(mtcars, mtcars[, c("mpg", 'cyl')], by = c("cyl")) %>% head()

Output

  mpg.x cyl disp  hp drat   wt  qsec vs am gear carb mpg.y
1    21   6  160 110  3.9 2.62 16.46  0  1    4    4  21.0
2    21   6  160 110  3.9 2.62 16.46  0  1    4    4  21.0
3    21   6  160 110  3.9 2.62 16.46  0  1    4    4  21.4
4    21   6  160 110  3.9 2.62 16.46  0  1    4    4  18.1
5    21   6  160 110  3.9 2.62 16.46  0  1    4    4  19.2
6    21   6  160 110  3.9 2.62 16.46  0  1    4    4  17.8

Solution

We can pass the argument suffix, a character vector of length 2 with the desired names. In our example, mpg_original (suffix _original) and mpg_new (suffix_new).

left_join(mtcars, mtcars[,c("mpg","cyl")], 
              by = c("cyl"), 
              suffix = c("_original", "_new")) %>% head()

Output

  mpg_original cyl disp  hp drat   wt  qsec vs am gear carb mpg_new
1           21   6  160 110  3.9 2.62 16.46  0  1    4    4    21.0
2           21   6  160 110  3.9 2.62 16.46  0  1    4    4    21.0
3           21   6  160 110  3.9 2.62 16.46  0  1    4    4    21.4
4           21   6  160 110  3.9 2.62 16.46  0  1    4    4    18.1
5           21   6  160 110  3.9 2.62 16.46  0  1    4    4    19.2
6           21   6  160 110  3.9 2.62 16.46  0  1    4    4    17.8

References

• stackoverflow
• Join two tbls together

Cómo representar una curva logarítmica en R

Problema

Queremos ajustar una curva logarítmica a un diagrama de dispersión.

library(ggplot2)
ggplot(mpg, aes(displ, hwy)) +
  geom_point()

Solución

Paquete base

plot(hwy ~ displ, mpg)
logEstimate <- lm(hwy ~ log(displ), data = mpg)
curve(coef(logEstimate)[1] + coef(logEstimate)[2] * log(x), add = TRUE)

ggplot2

ggplot(mpg, aes(displ, hwy)) +
  geom_point() +
  stat_smooth(method = "lm", formula = y ~ log(x))

Referencias

• stackoverflow

How to plot a log curve in R

Problem

We want to fit a logarithmic curve to a scatterplot.

library(ggplot2)
ggplot(mpg, aes(displ, hwy)) +
  geom_point()

Solution

Base package

plot(hwy ~ displ, mpg)
logEstimate <- lm(hwy ~ log(displ), data = mpg)
curve(coef(logEstimate)[1] + coef(logEstimate)[2] * log(x), add = TRUE)

ggplot2

ggplot(mpg, aes(displ, hwy)) +
  geom_point() +
  stat_smooth(method = "lm", formula = y ~ log(x))

References

• stackoverflow

How to do cross join in R?

Problem

We want to calculate a cross join, the Cartesian product of rows from tables —or elements of a vector— in the join. In other words, we want to combine each row from the first table with each row from the second table.

Solution

Two vectors

• expand.grid

expand.grid(1:5, 1:5)

• merge

merge(1:5, 1:5)

• Cross join with sqldf

library(sqldf)
df1 <- data.frame(a = 1:5)
df2 <- df1
sqldf("SELECT df1.a, df2.a FROM df1 
      CROSS JOIN df2")

• Results

   x y
1  1 1
2  2 1
3  3 1
4  4 1
5  5 1
6  1 2
7  2 2
8  3 2
9  4 2
10 5 2
11 1 3
12 2 3
13 3 3
14 4 3
15 5 3
16 1 4
17 2 4
18 3 4
19 4 4
20 5 4
21 1 5
22 2 5
23 3 5
24 4 5
25 5 5

More than two vectors

• expand.grid.

a <- c('europe', 'asia')
b <- c('co2', 'temperature')
c <- c('min', 'max')
expand.grid(a, b, c)

    Var1        Var2 Var3
1 europe         co2  min
2   asia         co2  min
3 europe temperature  min
4   asia temperature  min
5 europe         co2  max
6   asia         co2  max
7 europe temperature  max
8   asia temperature  max

References

• Merge Two Data Frames
• Create a Data Frame from All Combinations of Factor Variables
• Generating Cartesian product of strings in R
• Getting all combinations in R, repetition allowed