Mengonversi skrip menjadi fungsi

Pengantar Penulisan Fungsi di R

Richie Cotton

Data Evangelist at DataCamp

Template fungsi dasar

my_fun <- function(arg1, arg2) {
  # Do something
}

Tanda tangan

          function(arg1, arg2)

Body

                               {
  # Do something
}

library(readr)
test_scores_geography_raw <- read_csv("test_scores_geography.csv")

library(dplyr)
library(lubridate)
test_scores_geography_clean <- test_scores_geography_raw %>% 
  select(person_id, first_name, last_name, test_date, score) %>%
  mutate(test_date = mdy(test_date)) %>%
  filter(!is.na(score))

library(readr)
test_scores_english_raw <- read_csv("test_scores_english.csv")

library(dplyr)
library(lubridate)
test_scores_english_clean <- test_scores_english_raw %>% 
  select(person_id, first_name, last_name, test_date, score) %>%
  mutate(test_date = mdy(test_date)) %>%
  filter(!is.na(score))

library(readr)
test_scores_art_raw <- read_csv("test_scores_art.csv")

library(dplyr)
library(lubridate)
test_scores_art_clean <- test_scores_art_raw %>% 
  select(person_id, first_name, last_name, test_date, score) %>%
  mutate(test_date = mdy(test_date)) %>%
  filter(is.na(score))

library(readr)
test_scores_spanish_raw <- read_csv("test_scores_spanish.csv")

library(dplyr)
library(lubridate)
test_scores_spanish_clean <- test_scores_spanish_raw %>% 
  select(person_id, first_name, last_name, test_date, score) %>%
  mutate(test_date = mdy(test_date)) %>%
  filter(!is.na(score))

Buat template

import_test_scores <- function() {






}

Tempelkan skrip ke dalam body

import_test_scores <- function() {
  test_scores_geography_raw <- read_csv("test_scores_geography.csv")

  test_scores_geography_clean <- test_scores_geography_raw %>% 
    select(person_id, first_name, last_name, test_date, score) %>%
    mutate(test_date = mdy(test_date)) %>%
    filter(!is.na(score))
}

Pilih argumen

import_test_scores <- function(filename) {         # <- hanya 1 argumen
  test_scores_geography_raw <- read_csv("test_scores_geography.csv")

  test_scores_geography_clean <- test_scores_geography_raw %>% 
    select(person_id, first_name, last_name, test_date, score) %>%
    mutate(test_date = mdy(test_date)) %>%
    filter(!is.na(score))
}

Ganti nilai spesifik dengan argumen

import_test_scores <- function(filename) {
  test_scores_geography_raw <- read_csv(filename)  # <- ganti nama file spesifik

  test_scores_geography_clean <- raw_data %>% 
    select(person_id, first_name, last_name, test_date, score) %>%
    mutate(test_date = mdy(test_date)) %>%
    filter(!is.na(score))
}

Generalisasi nama variabel

import_test_scores <- function(filename) {
  test_scores_raw <- read_csv(filename)   # <- nama variabel digeneralisasi

  test_scores_clean <- test_scores_raw %>%       # <- nama variabel digeneralisasi
    select(person_id, first_name, last_name, test_date, score) %>%
    mutate(test_date = mdy(test_date)) %>%
    filter(!is.na(score))
}

Hapus assignment terakhir

import_test_scores <- function(filename) {
  test_scores_raw <- read_csv(filename)

  test_scores_raw %>%  # <- hapus assignment akhir
    select(person_id, first_name, last_name, test_date, score) %>%
    mutate(test_date = mdy(test_date)) %>%
    filter(!is.na(score))
}

Gunakan fungsi Anda

test_scores_geography <- import_test_scores("test_scores_geography.csv")
test_scores_english <- import_test_scores("test_scores_english.csv")
test_scores_art <- import_test_scores("test_scores_art.csv")
test_scores_spanish <- import_test_scores("test_scores_spanish.csv")

Argumen sample()

x: Vektor nilai untuk diambil sampelnya.
size: Berapa kali ingin mengambil sampel dari x?
replace: Ambil sampel dengan pengembalian atau tidak?
prob: Vektor bobot untuk tiap nilai x, totalnya satu.

Ayo berlatih!

Pengantar Penulisan Fungsi di R