Ch. 18: Pipes (notes only)

• pryr::object_size gives the memory occupied by all of its arguments (note that built-in object.size does not allow measuring multiple objects so can’t see shared space). This function is actually shown in chapter 18: Pipes
• Some functions do not work naturally with the pipe.
  • If you want to use assign with the pipe, you must be explicit about the environment

env <- environment()
assign("x", 100, envir = env)

• try, tryCatch, suppressMessages, and suppressWarnings from base R all also do not work well

Other pipes = ‘T pipe’, %T>% that returns left-hand side rather than right. Will let the plot output, but then continues. Notice that this doesn’t work quite the same way for ggplot as ggplot does output something

rnorm(100) %>%
  matrix(ncol = 2) %T>%
  plot() %>% 
  str()

##  num [1:50, 1:2] -0.25 -0.924 0.894 0.298 0.347 ...

iris %>% 
  select(Sepal.Length, Sepal.Width) %T>%  
  plot() %>% 
  select(Sepal.Length) %>% 
  head(10)

##    Sepal.Length
## 1           5.1
## 2           4.9
## 3           4.7
## 4           4.6
## 5           5.0
## 6           5.4
## 7           4.6
## 8           5.0
## 9           4.4
## 10          4.9

• %$% allows you to blow out the names of the arguments, I personally prefer using the with() function for this instead as I find it to be a little more readable…
  • The two examples below are equivalent

mtcars %$%
  cor(disp, mpg)

## [1] -0.8475514

mtcars %>%
  with(cor(disp, mpg))

## [1] -0.8475514