R Commands Quick Reference

Essential R commands for daily data science work

Quick lookup table of commonly used R commands for data manipulation, visualization, and analysis.

1 Data Import/Export

Task	Command	Example
Read CSV	`read.csv()`	`read.csv("data.csv")`
Read Excel	`readxl::read_excel()`	`read_excel("data.xlsx")`
Write CSV	`write.csv()`	`write.csv(df, "output.csv")`
Save RDS	`saveRDS()`	`saveRDS(data, "data.rds")`
Load RDS	`readRDS()`	`readRDS("data.rds")`

2 Data Manipulation (dplyr)

Task	Command	Example
Filter rows	`filter()`	`filter(df, age > 18)`
Select columns	`select()`	`select(df, name, age)`
Create columns	`mutate()`	`mutate(df, age_months = age * 12)`
Group data	`group_by()`	`group_by(df, category)`
Summarize	`summarise()`	`summarise(df, mean_age = mean(age))`
Sort	`arrange()`	`arrange(df, desc(age))`

3 Data Visualization (ggplot2)

Task	Command	Example
Scatter plot	`geom_point()`	`ggplot(df, aes(x, y)) + geom_point()`
Line plot	`geom_line()`	`ggplot(df, aes(x, y)) + geom_line()`
Bar plot	`geom_bar()`	`ggplot(df, aes(x)) + geom_bar()`
Histogram	`geom_histogram()`	`ggplot(df, aes(x)) + geom_histogram()`
Box plot	`geom_boxplot()`	`ggplot(df, aes(x, y)) + geom_boxplot()`

4 Statistical Functions

Task	Command	Example
Mean	`mean()`	`mean(x, na.rm = TRUE)`
Median	`median()`	`median(x, na.rm = TRUE)`
Standard deviation	`sd()`	`sd(x, na.rm = TRUE)`
Correlation	`cor()`	`cor(x, y, use = "complete.obs")`
Linear model	`lm()`	`lm(y ~ x, data = df)`
ANOVA	`aov()`	`aov(y ~ group, data = df)`

5 String Operations

Task	Command	Example
Concatenate	`paste()`	`paste("Hello", "World")`
Split string	`strsplit()`	`strsplit("a,b,c", ",")`
Find pattern	`grep()`	`grep("pattern", x)`
Replace pattern	`gsub()`	`gsub("old", "new", x)`
String length	`nchar()`	`nchar("hello")`

6 Package Management

Task	Command	Example
Install package	`install.packages()`	`install.packages("dplyr")`
Load package	`library()`	`library(dplyr)`
Update packages	`update.packages()`	`update.packages()`
List packages	`installed.packages()`	`installed.packages()`

7 Workspace Management

Task	Command	Example
List objects	`ls()`	`ls()`
Remove objects	`rm()`	`rm(x, y)`
Clear workspace	`rm(list = ls())`	`rm(list = ls())`
Working directory	`getwd()`	`getwd()`
Set directory	`setwd()`	`setwd("/path/to/dir")`

8 Data Types & Structure

Task	Command	Example
Data type	`class()`	`class(x)`
Structure	`str()`	`str(df)`
Dimensions	`dim()`	`dim(df)`
Column names	`names()`	`names(df)`
Summary	`summary()`	`summary(df)`
First rows	`head()`	`head(df, 10)`
Last rows	`tail()`	`tail(df, 10)`

9 Missing Values

Task	Command	Example
Check for NA	`is.na()`	`is.na(x)`
Remove NA	`na.omit()`	`na.omit(df)`
Complete cases	`complete.cases()`	`complete.cases(df)`

10 Quick Tips

Use ?function_name to get help
Use Tab for auto-completion in RStudio
Use Ctrl+Shift+M for pipe operator %>%
Use Ctrl+Shift+C to comment/uncomment code