obrl-soil

  # Sometimes you just want your iterated filenames to look nice.
  
  nth_fun <- function(x) {
    x <- abs(x)
    if (as.integer(substring(x, seq(nchar(x)), seq(nchar(x))))[nchar(x)] == 1) {
      return(paste0(x, 'st'))
    } else if (as.integer(substring(x, seq(nchar(x)), seq(nchar(x))))[nchar(x)] == 2) {
      return(paste0(x, 'nd'))
    } else if (as.integer(substring(x, seq(nchar(x)), seq(nchar(x))))[nchar(x)] == 3) {
      return(paste0(x, 'rd'))

obrl-soil

library(raster)

r <- raster('path\\to\\your\\file.ext')

winmin <- function(x) min(x, na.rm = T)
winmax <- function(x) max(x, na.rm = T)

focalmin <- focal(r, w = matrix(1, ncol = 3, nrow = 3), winmin)
focalmax <- focal(r, w = matrix(1, ncol = 3, nrow = 3), winmax)

obrl-soil

# for calculating the mode of a focal window over a categorical raster.
# Handling ties by retaining input cell value rather than default 'random'

winmode <- function(x) {
  y <- modal(x, na.rm = T, ties = 'NA')
  if (is.na(y)) { return(x[ceiling(length(x) / 2)]) } else {return(y)}}

# e.g.
# x <- raster(matrix(c(1:36), byrow = T, ncol = 6))
# f <- focal(x, w = matrix(1, ncol = 3, now = 3), fun = winmode)

obrl-soil

c5_usage_df <- function(x) {
  library(stringr)
  xt <- substr(x$output, 
               str_locate(x$output, "usage:")[2] + 4, 
               str_locate(x$output, 'Time')[1] - 1)
  
  xt <- gsub('\\n', '', xt)
  xt <- gsub('\\t', ', ', xt)
  xu <- as.data.frame(matrix(unlist(strsplit(xt, ", ")),
                             ncol =2, byrow=T),

obrl-soil

# for passing multiple variables to SQL in() queries

ids <- c(1,2,3)
idstring <- paste(ids, collapse=", ")
idstring <- paste0("'", idstring, "'")

#for a string of characters:
idch <- c("1", "2", "3")
idchstring <- paste0("'", idch, "'")
idchstring <- toString(idchstr)

obrl-soil

# subset out polygons from x that intersect polygons in y
# should work for other geom types too
get_intersecting <- function(x, y) {
  df     <- as.data.frame(st_intersects(x, y, sparse = FALSE))
  df$k   <- apply(df, MARGIN = 1, FUN = function(x) ifelse(any(x) == TRUE, T, F))
  x$k    <- df$k
  xout   <- filter(x, k == TRUE)
  x$k    <- NULL
  xout$k <- NULL
  return(xout)

obrl-soil

# a simplified version of the sampler used in https://github.com/obrl-soil/disaggregation 
# takes n random samples in each polygon of a spatialpolygonsdataframe
# note that n samples may not be acheived if the polygon shape is particularly convoluted

# indata = spatialpolygonsdataframe
# sample_rate = positive integer
# pid_field = character string - column name. if omitted, rownames used instead

poly_sampler <- function(indata = NULL, sample_rate = NULL, pid_field = NULL) {
  crs <- indata@proj4string 

obrl-soil

### sp Polygon objects ###
# x = spatialPolygons or spatialPolygonsDataFrame object only
# by_id = where true, adds a column to @data with a part count for each polygon. Promotes sPolys to sPolydf.
find_mp <- function(x = NULL, id_rows = FALSE) {

  nparts <- vector("list", length(x@polygons)) 
  
  for (i in seq_along(1:length(x@polygons))) {    
      n <- vector("list", length(x@polygons[[i]]@Polygons))
      for (j in seq_along(1:length(x@polygons[[i]]@Polygons))) {

obrl-soil

# documenting some file.path quirks on windows
# gdal translate is used below to copy a file. its on the system PATH, enabling easy access via system2

infile <- 'C:/Data/test.tif'
> setwd('C:/Data/space\\ test')
Error in setwd("C:/Data/space\\ test") : cannot change working directory
> setwd('"C:/Data/space test"')
Error in setwd("\"C:/Data/space test\"") : 
  cannot change working directory
> setwd('C:/Data/space test')

obrl-soil

library(tidyverse)
setwd('C:/DATA')
options(stringsAsFactors = FALSE)

# fake data
write.csv(tribble( ~col1, ~col2, ~col3,
                       1,   'a',    T,
                       2,   'b',   NA,
                       3,   'c',    F), 
          file = file.path(getwd(), 'csv1.csv'),