In tpemartin/econDV1091:

knitr::opts_chunk$set(echo = TRUE, eval=F)

library(klippy)
klippy::klippy()

---

makecondition

library(sf)

library(dplyr)
library(stringr)
library(ggplot2)
library(econDV)

Encapsulation {.tabset}

Blue print

# data import
{

}
# graph
{

}
# simplify
{

}
# crop
{

}
# zoom
{

}
# export
{

}
# restore (Throw in for safety)
{

}

Pseudocode

Prepare

• [ONLY ONE]{.alert-success} object to save your result.

• If the result involves with mutiple things, save them within that ONE object [using $ or [[resultName]] operation]{.alert-success}.

::: {.alert .alert-info} If result presents an action for users decide to take, it has to be an function. :::

# Declare a capsule (# type to be determined)
geoD <-
# data import
geoD$.data <- 
{

}
# graph
geoD$graph <- function()
{

}
# simplify
geoD$simplify <- function()
{

}
# crop
geoD$crop <- function()
{

}
# zoom
geoD$zoomIn <- function()
{

}
geoD$zoomOut <- function()
{

}
# export
geoD$export <- function()  
{

}
# restore (Throw in for safety)
geoD$restore <- function()
{

}

Pseudocode 2 (Encapsulation)

Save all the data you need and actions (i.e. function) you need [within the same object]{.alert-success} whose class has to be [environment]{.alert-success}.

• When retrieving any object value, or

• When saving any object value,

ALWAYS refers to its relevant environment except intermediate step object values.

dataSource <- "/Users/martinl/Dropbox/github-data/109-1-econDV/直轄市、縣市界線(TWD97經緯度)SHP格式/COUNTY_MOI_1090820.shp"

# Declare a capsule (# type to be determined)
geoD <- new.env()
# data import
geoD$.data <- 
{
  sf::st_read(dataSource)  
}
# graph
geoD$graph <- function()
{
  require(dplyr); require(ggplot2)
  geoD$.data %>%
    ggplot()+geom_sf() ->
    geoD$.graph

  geoD$.graph
}
# simplify
geoD$simplify <- function()
{
  rmapshaper::ms_simplify(geoD$.data) -> geoD$.data
}
# crop
geoD$crop <- function(...)
{
  argList <- list(...)
  sf::st_crop(
    geoD$.data,
    unlist(argList)
  ) -> geoD$.data
}
# zoom
geoD$zoomIn <- function()
{

}
geoD$zoomOut <- function()
{

}
# export
geoD$exportData <- function()  
{
  geoD$.data
}
# restore (Throw in for safety)
geoD$restore <- function()
{

}

Test 2

# initial data size
size0 <- object.size(geoD$.data)
# initial graphing
geoD$graph()
# data too much detail
geoD$simplify()
geoD$graph()
# faster graphing, but want main island
geoD$crop(
 xmin=120, xmax=123,
  ymin=22, ymax=26)
geoD$graph()
geoD$exportData() -> finalGeoData
sizeFinal <- object.size(finalGeoData)

Function prototype

GeoData_shp <- function(shpDataSource) {
  assertthat::assert_that(
    stringr::str_detect(
      basename(shpDataSource),
      stringr::regex(
        "shp$",
        ignore_case = T
      )
    ),
    msg = "The data source is not a shp data."
  )
  # Declare a capsule (# type to be determined)
  geoD <- new.env()
  # data import
  geoD$.data <- {
    sf::st_read(shpDataSource)
  }
  # graph
  geoD$graph <- function() {
    require(dplyr)
    require(ggplot2)
    geoD$.data %>%
      ggplot() +
      geom_sf() ->
    geoD$.graph
    geoD$.graph
  }
  # simplify
  geoD$simplify <- function() {
    rmapshaper::ms_simplify(geoD$.data) -> geoD$.data
  }
  # crop
  geoD$crop <- function(...) {
    argList <- list(...)
    sf::st_crop(
      geoD$.data,
      unlist(argList)
    ) -> geoD$.data
  }
  # zoom
  geoD$zoomIn <- function() {

  }
  geoD$zoomOut <- function() {

  }
  # export
  geoD$exportData <- function() {
    geoD$.data
  }
  # restore (Throw in for safety)
  geoD$restore <- function() {

  }
  return(geoD)
}

Function test

dataSource <- "/Users/martinl/Dropbox/github-data/109-1-econDV/直轄市、縣市界線(TWD97經緯度)SHP格式/COUNTY_MOI_1090820.shp"

geoD_beta <- GeoData_shp(dataSource)

# data too much detail
geoD_beta$simplify()
geoD_beta$graph()
# faster graphing, but want main island
geoD_beta$crop(
 xmin=120, xmax=123,
  ymin=22, ymax=26)
geoD_beta$graph()
geoD_beta$exportData() -> finalGeoData

::: {.alert .alert-info} GeoData_shp generates an instance (情境), geoD_beta, whose acting results depends on (1) an external state (dataSource, like 'exogenous shock' in Economics term) and (2) dynamic states (\$.data, like 'state variable' in Economics term), and (3) the action and state evolution are all kept within the instance itself (which is called Encapsulation(封包設計)).

Instance generator is usually named with Capital starting letter in contrast to an instance whose starting letter is in small case. :::

Exercise

Complete GeoData_shp instance initiator.

tpemartin/econDV1091 documentation built on Feb. 17, 2021, 6:37 a.m.