http://r4ds.had.co.nz/introduction.html

https://blog.rstudio.org/

2 Introduction

일반적인 Data science 프로젝트 단계

import

take data stored in a file, database, or web API, and load it into a data frame in R

Wrangling

tidying and transforming are called wrangling,
because getting your data in a form that’s natural to work with often feels like a fight

tidy (정돈)

Tidying your data  : 각 column 은 a variable,  각  row는 observation 으로 정돈한다.

Transform (변형)

Observation을 관심있는 범위로 좁히는 거 (ex. 한 도시의 모든 사람들,  작년의 모든 데이터….)
가지고 있는 variable로 새로운 variable을 만드는 function ( 거리와 시간으로 속도를 만든다…)
통계량을 요약하여 계산하는 거  ( 평균,갯수…)

Knowledge를 만드는 2가지 main engines

Visualization

raise new questions about the data

Models

Once you have made your questions sufficiently precise, you can use a model to answer them

communication

you can also communicate your results to others

bigdata

If you’re routinely working with larger data (10-100 Gb, say), you should learn more about data.table.
big data problem might actually be a small data problem in disguise
your big data problem is actually a large number of small data problems

1.3.2 Python, Julia, and friends

You will get better faster if you dive deep, rather than spreading yourself thinly over many topics
R is not just a programming language, but it is also an interactive environment for doing data science.

1.3.4 Hypothesis confirmation

data analysis into two camps:

• hypothesis generation ( data exploration)
• hypothesis confirmation ( confirmatory analysis).

etc

install.packages("tidyverse")
install.packages(c("nycflights13", "gapminder", "Lahman"))

데이터 재현

1. Run dput(mtcars) in R
2. Copy the output
3. In my reproducible script, type mtcars <- then paste.