# Define safe_readLines()
safe_readLines <- safely(readLines)
# Use the safe_readLines() function with map(): html
html <- map(urls, safe_readLines)
# Call str() on html
str(html)
# Extract the result from one of the successful elements
html[["example"]][["result"]]
# Define save_readLines() and html
safe_readLines <- safely(readLines)
html <- map(urls, safe_readLines)
# Examine the structure of transpose(html)
str(transpose(html))
# Extract the results: res
res<-transpose(html)[["result"]]
# Extract the errors: errs
errs<-transpose(html)[["error"]]
# Initialize some objects
safe_readLines <- safely(readLines)
html <- map(urls, safe_readLines)
res <- transpose(html)[["result"]]
errs <- transpose(html)[["error"]]
# Create a logical vector is_ok
is_ok<-map_lgl(errs,is_null)
# Extract the successful results
res[is_ok]
# Extract the input from the unsuccessful results
urls[!is_ok]
# Initialize n and mu
n <- list(5, 10, 20)
mu <- list(1, 5, 10)
# Create a sd list with the values: 0.1, 1 and 0.1
sd<-list(0.1,1,0.1)
# Edit this call to pmap() to iterate over the sd list as well
pmap(list(n, mu,sd), rnorm)
# Define list of functions
f <- list("rnorm", "runif", "rexp")
# Parameter list for rnorm()
rnorm_params <- list(mean = 10)
# Add a min element with value 0 and max element with value 5
runif_params <- list(min=0,max=5)
# Add a rate element with value 5
rexp_params <- list(rate=5)
# Define params for each function
params <- list(
rnorm_params,
runif_params,
rexp_params
)
# Call invoke_map() on f supplying params as the second argument
invoke_map(f,params, n = 5)
# Turn this snippet into find_breaks()
find_breaks<-function(x){
rng <- range(x, na.rm = TRUE)
seq(rng[1], rng[2], length.out = 30)
}
?seq
# Call find_breaks() on sims[[1]]
find_breaks(sims[[1]])
# Increase sample size to 1000
sims <- invoke_map(f, params, n = 1000)
# Compute nice_breaks (don't change this)
nice_breaks <- map(sims, find_breaks)
# Create a vector nice_titles
nice_titles<-c("Normal(10, 1)","Uniform(0, 5)","Exp(5)")
# Use pwalk() instead of walk2()
pwalk(list(sims,nice_breaks,main=nice_titles), hist,xlab="")
# Pipe this along to map(), using summary() as .f
sims %>%
walk(hist) %>% map(summary)