#data frames

The 7 layer burrito of #networking in terms for #developers

Open System Interconnection (OSI) model is a conceptual framework that defines how to implement network protocols. It was developed by the International Standards Organization (ISO) in order to standardize communication functions. The goal is interoperability of different systems through a standard protocol. The concept is based on the work of Charles Bachman at Honeywell Information Services.

So far it’s been established that: [] and $ selects columns/rows 

[[]] allows for more selective element operations--only allows you to pull out single values or columns in data frames--**note: when using lists, you can only use [[]]

we will create a variable (a) to understand this [[]] subset

a<-list(1:4,4:8,z=letters[1:4])

structurally: 

> str(a) List of 3 $  : int [1:4] 1 2 3 4 $  : int [1:5] 4 5 6 7 8 $ z: chr [1:4] "a" "b" "c" "d"

when using [[]]

it is most relevant for lists

you can specify a single element, or a string using c()

(1) using a single number or letter

> a[[1]] [1] 1 2 3 4

> a[['z']] [1] "a" "b" "c" "d"