All R Faq Solutions on Gang of Coders

Total of 160 R Faq Solutions

rank and order in R

R Sorting R Faq

Error: unexpected symbol/input/string constant/numeric constant/SPECIAL in my code

Simultaneously merge multiple data.frames in a list

R List Merge Dataframe R Faq

How and when should I use on.exit?

Split data frame string column into multiple columns

R String Dataframe Split R Faq

Create an ID (row number) column

R Dataframe R Faq

Combine two data frames by rows (rbind) when they have different sets of columns

R Dataframe R Faq

Export data from R to Excel

Reshaping multiple sets of measurement columns (wide format) into single columns (long format)

R Reshape Tidyr Reshape2 R Faq

ggplot with 2 y axes on each side and different scales

R Ggplot2 R Faq

Subset rows in a data frame based on a vector of values

Numeric comparison difficulty in R

R Floating Point Comparison Comparison Operators R Faq

Why are these numbers not equal?

R Floating Point Floating Accuracy R Faq

How do I get a list of built-in data sets in R?

R Dataset R Faq

How to debug "contrasts can be applied only to factors with 2 or more levels" error?

R Regression Lm Glm R Faq

Determine path of the executing script

R File Path Rscript R Faq

Convert integer to class Date

How to import multiple .csv files at once?

Add regression line equation and R^2 on graph

R Ggplot2 Linear Regression R Faq

Grouping functions (tapply, by, aggregate) and the *apply family

R Lapply Sapply Tapply R Faq

What are the main differences between R data files?

R R Faq Rdata Rda

Change R default library path using .libPaths in Rprofile.site fails to work

R Rstudio R Faq Library Path

Find the day of a week

How do I make a list of data frames?

R List Dataframe R Faq

Use dynamic name for new column/variable in `dplyr`

ggplot2 line chart gives "geom_path: Each group consist of only one observation. Do you need to adjust the group aesthetic?"

R Ggplot2 R Faq

Remove rows with all or some NAs (missing values) in data.frame

R Dataframe Filter Missing Data R Faq

Drop data frame columns by name

R Dataframe R Faq

Use of ~ (tilde) in R programming Language

R R Faq R Formula

Reshaping data.frame from wide to long format

R Dataframe Reshape R Faq

Numbering rows within groups in a data frame

R Dataframe R Faq

What are the differences between "=" and "<-" assignment operators in R?

R Assignment Operator R Faq

Speed up the loop operation in R

Performance R Loops Rcpp R Faq

Error: could not find function ... in R

R Function Error Handling R Faq

Remove duplicated rows

R Duplicates R Faq

How to find common elements from multiple vectors?

How to remove all whitespace from a string?

R Regex String R Faq

Replace all 0 values to NA

Replacing NAs with latest non-NA value

R data.table Zoo R Faq

R memory management / cannot allocate vector of size n Mb

R Matrix Vector Memory Management R Faq

Convert data.frame column format from character to factor

R Dataframe Character R Faq

Error in if/while (condition) {: missing Value where TRUE/FALSE needed

Aggregate / summarize multiple variables per group (e.g. sum, mean)

R Dataframe data.table Aggregate R Faq

Filter data.frame rows by a logical condition

R Dataframe Subset R Faq

What does %>% function mean in R?

R Syntax Dplyr Magrittr R Faq

Group by multiple columns in dplyr, using string vector input

Add legend to ggplot2 line plot

R Ggplot2 Legend R Faq

Installing older version of R package

R Installation Version R Faq

How do you use "<<-" (scoping assignment) in R?

R Scoping Lexical Scope R Faq

How to use a variable to specify column name in ggplot

R Ggplot2 Tidyeval R Faq Nse

Dynamically select data frame columns using $ and a character value

R Dataframe R Faq

Should I use a data.frame or a matrix?

R Matrix Dataframe R Faq

Only read selected columns

Pass a data.frame column name to a function

R Dataframe R Faq

Order discrete x scale by frequency/value

R Ggplot2 R Faq

Reorder levels of a factor without changing order of values

R Sorting Levels R Faq

How to convert a factor to integer\numeric without loss of information?

R Casting R Faq

Plot two graphs in same plot in R

R Plot Ggplot2 R Faq

Count number of rows within each group

R Dataframe Aggregate R Faq

Using R to download zipped data file, extract, and import data

R Connection Zip R Faq

How should I deal with "package 'xxx' is not available (for R version x.y.z)" warning?

R Installation Repository Package R Faq

Convert UNIX epoch to Date object

Warning message: In `...` : invalid factor level, NA generated

R Warnings R Faq

Finding ALL duplicate rows, including "elements with smaller subscripts"

R Duplicates R Faq

Why can't R's ifelse statements return vectors?

R If Statement Vectorization R Faq

How to read data when some numbers contain commas as thousand separator?

Split comma-separated strings in a column into separate rows

R String Split R Faq

Combine two or more columns in a dataframe into a new column with a new name

R Dataframe Multiple Columns R Faq

How can I view the source code for a function?

R Function R Faq

What is the difference between require() and library()?

R Package R Faq

Controlling number of decimal digits in print output in R

R Precision Digits R Faq Output Formatting

What does "S3 methods" mean in R?

R Oop R Faq R S3 R S4

How to unload a package without restarting R

R Package R Faq

Select the row with the maximum value in each group

R Dataframe R Faq

How to search for "R" materials?

The difference between bracket [ ] and double bracket [[ ]] for accessing the elements of a list or dataframe

R List Dataframe Extract R Faq

Test if a vector contains a given element

Unique combination of all elements from two (or more) vectors

Error in <my code> : object of type 'closure' is not subsettable

Scheduling R Script

R Windows Schedule R Faq

Drop unused factor levels in a subsetted data frame

R Dataframe R Factor R Faq

General suggestions for debugging in R

R Debugging R Faq

Set default CRAN mirror permanent in R

How to make a great R reproducible example

Create an empty data.frame

R Dataframe R Faq

Multiline Comment Workarounds?

R Comments R Faq

Confusion between factor levels and factor labels

R R Factor R Faq

Paste multiple columns together

Quickly reading very large tables as dataframes

R Import Dataframe R Faq

List distinct values in a vector in R

R Vector Distinct Values R Faq

How do you specifically order ggplot2 x axis instead of alphabetical order?

R Ggplot2 R Faq

Rename multiple columns by names

R Dataframe Rename R Faq

Converting year and month ("yyyy-mm" format) to a date?

R Date Posix Zoo R Faq

How to name variables on the fly?

Convert a vector into a list, each element in the vector as an element in the list

Fitting a density curve to a histogram in R

R Histogram Curve Fitting R Faq

Apply several summary functions on several variables by group in one call

R Aggregate R Faq

Get filename without extension in R

How to subset matrix to one column, maintain matrix data type, maintain row/column names?

R Matrix Subset R Faq

Collapse / concatenate / aggregate a column to a single comma separated string within each group

R Aggregate R Faq

Read an Excel file directly from a R script

Understanding the order() function

R Sorting R Faq

How to find the statistical mode?

R Statistics R Faq

Counting the number of elements with the values of x in a vector

R Vector Count R Faq

Generate a dummy-variable

How to sum a variable by group

R Dataframe Aggregate R Faq

How to write trycatch in R

R Exception Exception Handling Try Catch R Faq

Select rows from a data frame based on values in a vector

What does "The following object is masked from 'package:xxx'" mean?

Counting unique / distinct values by group in a data frame

R Dataframe Distinct Values R Faq

Pasting two vectors with combinations of all vectors' elements

How do I deal with special characters like \^$.?*|+()[{ in my regex?

How can two strings be concatenated?

R String Concatenation R Faq

How to plot all the columns of a data frame in R

R Dataframe Plot R Faq

Calculate the mean by group

R Dataframe R Faq

Combine a list of data frames into one data frame by row

R List Dataframe R Faq

How to add leading zeros?

R Formatting Number Formatting R Faq

Why is `vapply` safer than `sapply`?

Why is `[` better than `subset`?

R Filter Subset R Faq

Extracting specific columns from a data frame

R Dataframe R Faq

R: what are Slots?

Oop R S4 Slot R Faq

Convert a dataframe to a vector (by rows)

R Dataframe Vector R Faq

How to plot a function curve in R

R Ggplot2 Plot Lattice R Faq

How to split a data frame?

R Split Dataframe R Faq

Subset / filter rows in a data frame based on a condition in a column

R Dataframe Subset R Faq

Elegant way to check for missing packages and install them?

R Packages R Faq

Side-by-side plots with ggplot2

R Ggplot2 Visualization R Faq

Sample random rows in dataframe

R Dataframe Random R Faq

Re-ordering factor levels in data frame

R Dataframe Levels R Faq

Using ggplot2, can I insert a break in the axis?

R Ggplot2 R Faq

Round up from .5

R Rounding R Faq

How to subtract/add days from/to a date?

How can I trim leading and trailing white space?

R Whitespace Trim Removing Whitespace R Faq

do-while loop in R

R Loops Repeat Do While R Faq

duplicate 'row.names' are not allowed error

ending "+" prompt in R

How does one reorder columns in a data frame?

R Sorting Dataframe R Faq

Access variable value where the name of variable is stored in a string

R Variables R Faq

How to load packages in R automatically?

R Loading R Package R Faq Defaults

ggplot's qplot does not execute on sourcing

R Ggplot2 R Faq

Test if characters are in a string

R Regex String R Faq

Order Bars in ggplot2 bar graph

R Ggplot2 R Faq

Plotting two variables as lines using ggplot2 on the same graph

R Ggplot2 Graph Time Series R Faq

Why do R objects not print in a function or a "for" loop?

R For Loop Printing R Faq

Split data.frame based on levels of a factor into new data.frames

R Dataframe R Faq

R round to nearest .5 or .1

R Rounding R Faq

How to join (merge) data frames (inner, outer, left, right)

Sort (order) data frame rows by multiple columns

R Sorting Dataframe R Faq

Cleaning up factor levels (collapsing multiple levels/labels)

R R Factor R Faq

How to reshape data from long to wide format

R Reshape R Faq

Count number of rows per group and add result to original data frame

R Count Aggregate R Faq

How to sort a character vector where elements contain letters and numbers in R?

R Sorting R Faq

How can I remove an element from a list?

R List Indexing R Faq

Evaluate expression given as a string

How to save a plot as image on the disk?

R Plot Ggplot2 Lattice R Faq

Formatting Decimal places in R

R Formatting Rounding R Faq

How to subtract years?

R Date Date Arithmetic R Faq

Why is it not advisable to use attach() in R, and what should I use instead?

R Dataframe R Faq

What's the biggest R-gotcha you've run across?

Concatenate a vector of strings/character