Some snippets on Tidyverse usage

Tibbles and strings

Combining mutate() with str_replace() and str_remove()

some_tibble %>%
  mutate(New_col = str_replace(Old_col, "pattern", "replacement"))

some_tibble %>%
  mutate(New_col = str_remove_all(Old_col, "pattern to remove"))

Move every other row into two columns

Some snippets on using map() to read files

# Read a list of input files into a list
tmp <- list.files(full.names = FALSE, pattern = ".tsv") %>%
  # Keep the file names as the names of the list elements
  set_names() %>% 
  map(read_tsv, col_names = FALSE)

# Reduce the list to a single dataframe. Keep the filenames (list element names) in column 1
# The column name will be "sampleName"
df <- bind_rows(tmp, .id = "sampleName")

Arrange rows in custom order

Use the match function to create a vector of indexes (row numbers) of the rows matching the strings “Honda Civic” and “Camaro Z28” in the column “car”. Put this vector into arrange() to arrange the rows accordingly.

library(tidyverse)
rownames_to_column(mtcars, var = "car") %>% 
  arrange(match(car, c("Honda Civic", "Camaro Z28")))

#              car  mpg cyl  disp  hp drat    wt  qsec vs am gear carb
# 1    Honda Civic 30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
# 2     Camaro Z28 13.3   8 350.0 245 3.73 3.840 15.41  0  0    3    4
# 3      Mazda RX4 21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
# 4  Mazda RX4 Wag 21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
# 5     Datsun 710 22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
# 6 Hornet 4 Drive 21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1

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