Data Wrangling with Dplyr and Tidyr Cheat Sheet , Cheat Sheet of Data Structures and Algorithms

Download Data Wrangling with Dplyr and Tidyr Cheat Sheet and more Cheat Sheet Data Structures and Algorithms in PDF only on Docsity! Data Wrangling with dplyr and tidyr Cheat Sheet RStudio® is a trademark of RStudio, Inc. • CC BY RStudio • info@rstudio.com • 844-448-1212 • rstudio.com Syntax - Helpful conventions for wrangling dplyr::tbl_df(iris) Converts data to tbl class. tbl’s are easier to examine than data frames. R displays only the data that fits onscreen: dplyr::glimpse(iris) Information dense summary of tbl data. utils::View(iris) View data set in spreadsheet-like display (note capital V). Source: local data frame [150 x 5] Sepal.Length Sepal.Width Petal.Length 1 5.1 3.5 1.4 2 4.9 3.0 1.4 3 4.7 3.2 1.3 4 4.6 3.1 1.5 5 5.0 3.6 1.4 .. ... ... ... Variables not shown: Petal.Width (dbl), Species (fctr) dplyr::%>% Passes object on left hand side as first argument (or . argument) of function on righthand side. "Piping" with %>% makes code more readable, e.g. iris %>% group_by(Species) %>% summarise(avg = mean(Sepal.Width)) %>% arrange(avg) x %>% f(y) is the same as f(x, y) y %>% f(x, ., z) is the same as f(x, y, z ) Reshaping Data - Change the layout of a data set Subset Observations (Rows) Subset Variables (Columns) F M A Each variable is saved in its own column F M A Each observation is saved in its own row In a tidy data set: & Tidy Data - A foundation for wrangling in R Tidy data complements R’s vectorized operations. R will automatically preserve observations as you manipulate variables. No other format works as intuitively with R. FAM M * A * tidyr::gather(cases, "year", "n", 2:4) Gather columns into rows. tidyr::unite(data, col, ..., sep) Unite several columns into one. dplyr::data_frame(a = 1:3, b = 4:6) Combine vectors into data frame (optimized). dplyr::arrange(mtcars, mpg) Order rows by values of a column (low to high). dplyr::arrange(mtcars, desc(mpg)) Order rows by values of a column (high to low). dplyr::rename(tb, y = year) Rename the columns of a data frame. tidyr::spread(pollution, size, amount) Spread rows into columns. tidyr::separate(storms, date, c("y", "m", "d")) Separate one column into several. wwwwwwA1005A1013A1010A1010 wwp11010 745451009wwp11010745451009 wwp11010 745451009wwp11010745451009 wppw1100 7071104510091 0945wwwww11010101010 wwwwdplyr::filter(iris, Sepal.Length > 7) Extract rows that meet logical criteria. dplyr::distinct(iris) Remove duplicate rows. dplyr::sample_frac(iris, 0.5, replace = TRUE) Randomly select fraction of rows. dplyr::sample_n(iris, 10, replace = TRUE) Randomly select n rows. dplyr::slice(iris, 10:15) Select rows by position. dplyr::top_n(storms, 2, date) Select and order top n entries (by group if grouped data). < Less than != Not equal to > Greater than %in% Group membership == Equal to is.na Is NA <= Less than or equal to !is.na Is not NA >= Greater than or equal to &,|,!,xor,any,all Boolean operators Logic in R - ?Comparison, ?base::Logic dplyr::select(iris, Sepal.Width, Petal.Length, Species) Select columns by name or helper function. Helper functions for select - ?select select(iris, contains(".")) Select columns whose name contains a character string. select(iris, ends_with("Length")) Select columns whose name ends with a character string. select(iris, everything()) Select every column. select(iris, matches(".t.")) Select columns whose name matches a regular expression. select(iris, num_range("x", 1:5)) Select columns named x1, x2, x3, x4, x5. select(iris, one_of(c("Species", "Genus"))) Select columns whose names are in a group of names. select(iris, starts_with("Sepal")) Select columns whose name starts with a character string. select(iris, Sepal.Length:Petal.Width) Select all columns between Sepal.Length and Petal.Width (inclusive). select(iris, -Species) Select all columns except Species. Learn more with browseVignettes(package = c("dplyr", "tidyr")) • dplyr 0.4.0• tidyr 0.2.0 • Updated: 1/15 wwwwwwA1005A1013A1010A1010 devtools::install_github("rstudio/EDAWR") for data sets