Long and wide - tidyr

library(tidyverse)

Wide to long format

boys <- data.frame(name = c("Josef Novák", "Jakub Patočka", "Miroslav Müller", 
                            "Karel Rychlý", "Matěj Průha", "Václav Záveský"), 
                   math = c(1,1,3,2,3,3), cz = c(2,1,1,1,1,3), 
                   en = c(NA, NA, 1,1,1,1), de = c(2,1,NA,NA,NA,2),
                   bio = c(2,2,NA,NA,2,3), his = c(NA, NA, 1,2,NA, NA), 
                   fy = c(NA,NA,NA,2,2,NA), geo = c(1,2,1,NA, NA, NA))

Imagine you would like to plot the boys’ grades like this: BREAKOUT ROOMS, SUGGEST DATA FRAME STRUCTURE

boys_long %>% ggplot(mapping = aes(x = name, y = grade, color = course)) +
  geom_jitter(position = position_jitter(width = 0.2, height = 0, seed = 1)) +
  geom_violin(aes(group = name), fill = NA)

NEUKAZUJ!!! ############################################################################

formerly: gather

Pivot wider (complement to pivot_longer)

formerly spread

vignette("pivot")

Course on DataCamp: https://learn.datacamp.com/courses/reshaping-data-with-tidyr

Separate

You want to have first names and surnames in two separate columns

If you need a more complicated splitting, use extract (extracts regular expression groups).

Unite

You want the values in the first_name and the surname columns to form a sequence of surname and first name separated by a comma and a space. Keep the original two columns, too.