peterhurford

# For every AWS availability zone and instance I care about, check the spot
# price for the last ninety days and generate stats about which spot instance
# gives the best deal.

import boto
import boto.ec2
from vowpal_platypus.utils import mean


REGIONS = {'us-east-1': ['us-east-1a', 'us-east-1b', 'us-east-1c', 'us-east-1e'],

peterhurford

Notes from reading through R Packages by Hadley Wickham. This is meant to review, not replace, a thorough readthrough. I mainly wrote this as a personal review, since writing summaries and attempting to teach others are some of the best ways to learn things.

Introduction

• Packages are used to organize code together so that it can be used repeatedly and shared with others.

• A lot of work with packages is done via the devtools package.

peterhurford

#' Calculate a dep_var for the iris dataset based on the iris dataset.
#'
#' @param by character. \code{length} to go by \code{Petal.Length} or \code{width} to go by \code{Petal.Width}.
iris_with_dep_var <- validations::ensure(pre = list(by %in% c("length", "width")),
  function(by = "length") {
    if (identical(by, "length")) {
      plyr::ddply(iris, plyr::.(Species), summarize, dep_var = ifelse(any(Petal.Length >= 4), 1, 0))
    } else {
      plyr::ddply(iris, plyr::.(Species), summarize, dep_var = ifelse(any(Petal.Width >= 4), 1, 0))

peterhurford

Total kg per capita consumed of beef, veal, pork, poultry, and sheep meat by country in 2016, adapted from OECD Data on Meat Consumption. Per-animal breakdown is available as a CSV.

IND	2.944374911
BGD	3.358927799
ETH	4.449228451
NGA	6.061917778
TZA	6.986943733
MOZ	7.117845532
SSA	8.798326892

peterhurford

The Fledgling Languages list has almost 100 programming languages that are up-and-coming but not widely popular. I looked at them all and here are a few of my favorites:

...This language looks so much like English! http://www.availlang.org/

...This language claims to have the speed of C++, the expressiveness of Python, and tons of additional safety with first-level contracts http://cobra-language.com/

...Code that looks exactly like Ruby, but is statically type-checked and compiled into efficient native code http://crystal-lang.org/

...What it would look like if Haskell and Clojure had a baby https://github.com/LuxLang/lux

peterhurford

# Debugging in R is much better than many languages, but sometime it can be
# frustrating.  Here's a function that makes it even more frustrating --
# it only works when you try to debug it!

# The challenge:
### Write a function that, if the function has a browser in it, will execute
### every line correctly, but if it does not have a browser in it, it will
### error.

# The solution:

peterhurford

While reading Hadley's Advanced R book chapter on function operators (see our work on creating a set of answers here), I came across this fact about lazy evaluation:

The function operators we’ve seen so far follow a common pattern:

funop <- function(f, otherargs) { function(...) { # maybe do something res <- f(...) # maybe do something else

peterhurford

1a.) Why would one use a symbol instead of a string?

1b.) Why would someone use a string instead of a symbol?

2a.) What is the difference between a lambda, a block and a proc?

2b.) What does -> (a) {p a}["Hello world"] do?

peterhurford

Rspresso

(Name and initial idea from robertzk.)

Assignment

number = 42 --> RSPRESSO! --> number <- 42

Functions

peterhurford

What does a ||= b mean?

What is the difference between a symbol and a string?

What is the difference between ' and " in Ruby?