library(sf)
library(dplyr)
f <- system.file("extdata", "farmer_spatial.csv", package = "geospaar")
farmers <- readr::read_csv(f)
farmers <- farmers %>% select(uuid, x, y) %>% distinct() %>% 
  st_as_sf(., coords = c("x", "y"))
f <- system.file("extdata", "districts.shp", package = "geospaar")
dists <- read_sf(f)
st_crs(farmers) <- st_crs(dists)

# join farmers with districts (h/t https://mattherman.info/blog/point-in-poly/)
farmers_in_dists <- st_join(farmers, dists, join = st_within) %>%
  tidyr::drop_na()
farmer_count <- count(as_tibble(farmers_in_dists), distName)
dists_w_farmers <- left_join(dists, farmer_count) %>% 
  mutate(n = ifelse(is.na(n), 0, n))

png("figures/sms-farmers.png", height = 4, width = 5, res = 300,
    units = "in")
plot(dists_w_farmers["n"], breaks = c(0, 5, 10, 15, 20, 50, 500), 
     reset = FALSE, main = "Number of SMS Farmers by District")
plot(farmers %>% filter(uuid %in% unique(farmers_in_dists$uuid)) %>%
       st_geometry(), add = TRUE, pch = "+", col = "cyan", cex = 0.5)
dev.off()

Today

  • Assignment 1 questions
  • The R ecosystem
  • Building blocks of R: data types, functions, etc

The R Ecosystem

  • What data types are used in R, and how do they differ?
  • What data structures are there in R, how do they vary by dimension, and which data structures can hold more than 1 data type?
  • What are the similarities and differences between a primitive, an operator, a control structure, and a package function?
  • What is the relationship between a generic function and an R class?
  • What is object-oriented program, and how is it (idiosyncratically used in R?

The R Ecosystem

The R Ecosystem

Common objects

Credit: L. Song

The R Ecosystem

Data types

There are 6 atomic data types:

  • character e.g. 'hello world', 'abc'
  • double (real or decimal) e.g. 10, 3.14, 1e10
  • integer e.g. 1L
  • logical e.g. TRUE, FALSE, T, F
  • complex e.g. 1 + 3i (not commonly used by us)
  • raw (rarely used by us)

The R Ecosystem

Special data types

  • NULL: Does not exist
  • Missing data: NA. A special logical type that converts into the type it is associated with.
  • Infinity: Inf (e.g. 1 / 0) and -Inf (e.g. -1 / 0. A special double type.
  • Undefined value: NaN. Also a special double type. (e.g. 0 / 0)

The R Ecosystem

Special data types

  • Date: as.Date('1970-1-5')
  • Time: as.POSIXct('1970-1-5')
  • Factor: factors are integers with associated labels.

The R Ecosystem

Checking data type

  • typeof(x)

  • is.xxx(x):

    • e.g. is.double(x), is.integer(x), is.logical(x), is.character(x), is.complex(x), is.raw(x), is.factor

    • is.numeric(x)

    • e.g. is.na(y), is.nan(y), is.null(y), is.infinite(y), is.finite(y).

The R Ecosystem

Converting data type

  • as.xxx(x):

    • e.g. as.numeric(x), as.double(x), as.character(x), as.integer(x), as.logical(x), as.complex(x), as.raw(x), as.factor(x), as.Date(x), as.POSIXct(x).

  • logical < integer < double < character

The R Ecosystem

Data structures

  • Atomic vectors (most commonly thought of kind):

    • A sequence of objects of the same class.

    • Arrays and matrices are vectors with more than one dimension.

      • Matrices have 2 dimensions.
      • Arrays could have higher dimensions.

  • Lists

    • Lists can contain objects of different classes.
    • Lists can be converted list-matrix or list-array by defining dimensions.
    • data.frame and tibble are S3 objects that are lists in tabular form

The R Ecosystem

Vectors

Credit: L. Song

Extras

Below here

Tips and Tricks

  • Tab completion and shortcuts
  • Reusing code
  • Code syntax
  • Posting guide

Knowing how to get help as a skillset

  • Slack posting guide
  • Getting help via the search engine
  • (Eventually) posting to listserves

Search Engine Science

  • Sometimes you just need the error message

Search Engine Science

  • Sometimes you need to search

    fatal: unable to access 'https://github.com/agroimpacts/xyz346.git/': 
error setting certificate verify locations:
 CAfile: C:/Users/xyz/Desktop/ADP/RStudio/xyz346/Git/mingw64/ssl/
 certs/ca-bundle.crt
 CApath: none

  • How you search matters

Listserves