r.md

R

Base R

fahrenheit_to_celsius <- function(temp_F) {
  temp_C <- (temp_F - 32) * 5 / 9
  return(temp_C) 
}

note: return is optional; variable on last line is returned by default.

Tidyverse

• define a factor: factor(colname, ordered = TRUE, levels = c('a', 'b', 'c'))
• convert column to factor type (using current order of data as factor level order: df %>% mutate(colname = factor(colname, ordered = TRUE, levels = unique(colname))
• General sorting of factors approach: numeric_levels <- sort(unique(numeric_vector)) numeric_factor_vector <- factor(numeric_vector, levels = numeric_levels)
• Suppress package loading messages: suppresspackagestartupmessages({library(readxl) ...})
• Read args from command line: args <- commandArgs(trailingOnly = TRUE) input_filename <- args[1] sheetname <- args[2]
• How to reference a column names as a variable: mtcars %>% filter(get(var) == 4)

Non-equi joins

• OPEN GITHUB ISSUE: join_by(): Syntax for generic joins · Issue #2240 · tidyverse/dplyr

• One guys approach: In between a rock and a conditional join

• Another guys approach: Thought process to choose a Tidyverse approach: join, mutate + map, or other

• Fuzzy join: dgrtwo/fuzzyjoin: Join tables together on inexact matching

• TEASED IN 2015 FOR DPLYR: dplyr 0.4.0

Tidyverse

• Filter only if a condition

You could do

library(dplyr)
y <- ""
data.frame(x = 1:5) %>% 
  {if (y=="") filter(., x>3) else filter(., x<3)} %>% 
  tail(1)

or

data.frame(x = 1:5) %>% 
 filter(if (y=="") x>3 else x<3) %>%  
  tail(1)

or even store your pipe in the veins of

mypipe <- . %>% tail(1) %>% print
data.frame(x = 1:5) %>% mypipe

stackoverflow

GGPlot

• Line plot for discrete x-axis:

  ggplot(data, aes(x=factor(year), y=dist, group=1)) + geom_line() + geom_point()

• Hide aes legend ... + guides(color = FALSE, size = FALSE)

• Hide geom legend ... + geom_point(..., show.legend = FALSE)

• Scale axes ... + scale_y_continuous(name="Stopping distance", limits=c(0, 150))

• linetype options: linetype = {"blank"|"solid"|"dashed"|"dotted"|"dotdash"|"longdash"|"twodash"}

• add geom_text (label) with LaTeX formatting

  library(latex2exp) ... + geom_text(data, aes(x, y, label = TeX(colname, output='character')), parse = TRUE)

• Color scales and palettes

  with palette brewer:

  scale_color_brewer(palette="Set1")

  with Wes Anderson themes:

  library(wesanderson) ... + scale_color_manual(values=wes_palette(n=3, name="GrandBudapest"))

  with Grayscale:

  scale_color_grey(start=0.8, end=0.2) # start and end are optional

  with Gradients:

  scale_fill_gradient(low="blue", high="red") # sequential gradient, 2 colors scale_color_gradient2(midpoint=mid, low="blue", mid="white", high="red", space ="Lab" ) # diverging gradient scale_color_gradientn(colours = rainbow(5)) # between n colors

• Axis number format with commas (not scientific notation)

  without scientific notation:

  scale_y_log10(labels = function(n){format(n, scientific = FALSE)})

  with commas

  scale_y_log10(labels = scales::comma) scale_y_log10(labels = function(n){format(n, scientific = FALSE, big.mark = ",")})

  just 10^x

  scale_y_log10(labels = scales::trans_format("log10", scales::math_format(10^.x)))

• How to remove padding space on axis: scale_x_continuous(limits = ..., expand = expansion(mult = c(0,0)))

• Theme font size changes theme(axis.text.x = element_text(size = 12))

Useful Links

• Themes
  • Complete themes --- ggtheme • ggplot2
  • Modify components of a theme --- theme • ggplot2
  • ggplot2 themes and background colors : The 3 elements - Easy Guides - Wiki
• Facet Labels
  • Nested Facet Labels
    • Nested facet plot with ggplot2
    • ggh4x/facet_nested.R at master · teunbrand/ggh4x · GitHub
    • Facets (ggplot2)
    • ggplot2: have common facet bar in outer facet panel in 3-way plot
    • Nested facets in ggplot2 spanning groups
  • Removing Facet Labels
    • Remove first part of a double label:
    • Ggplot: How to remove axis labels on selected facets only?
  • Labels documentation:
    • labellers
    • facet_grid
    • labeller
    • as_labeller
  • Label Bar Charts
    • geomtext on facet dodged barplot
    • geom_text
    • geom_text
    • r gallery - add text tables
    • stackoverflow - specify geom text position by top/bottom/left/right
• Add target line to chart: How to add different lines for facets
• Excel: 3 Ways to Add a Target Line to an Excel Pivot Chart
• Bars on Log Plots
  • geom_segment hack: direction of bars in ggplot barplot with log scale axes
  • don't do it: Graph Makeover: Bars on a log scale

RStudio

• Show all panes: Ctrl + Alt + Shift + 0