Data Structure: Vector

A list common functions in R for working with vector objects:

1. Creating Vectors

c() – Combine values into a vector.
seq() – Generate a sequence of numbers.
rep() – Repeat elements to form a vector.

2. Accessing and Modifying Vectors

length() – Get the length of a vector.
[] – Subset elements of a vector.
append() – Append elements to a vector.
unique() – Extract unique elements from a vector.
sort() – Sort elements of a vector.
rev() – Reverse elements of a vector.
which() – Find indices of elements that meet a condition.

3. Vector Math and Operations

sum() – Sum of vector elements.
mean() – Calculate the mean.
median() – Calculate the median.
sd() – Calculate the standard deviation.
var() – Calculate the variance.
min() / max() – Find the minimum/maximum value.
range() – Get the range (min and max).
diff() – Lagged differences of vector elements.
prod() – Product of elements.

4. Logical and Conditional Functions

any() – Check if any elements are TRUE.
all() – Check if all elements are TRUE.
is.na() – Check for NA values in the vector.
na.omit() – Remove NA values from the vector.
ifelse() – Vectorized conditional statements.

5. Applying Functions to Vectors

sapply() – Apply a function to each element and simplify the result.
vapply() – Similar to sapply() but allows specifying output type.

6. Character Vector Functions

paste() / paste0() – Concatenate elements.
tolower() / toupper() – Convert to lowercase or uppercase.
nchar() – Count characters in elements.
substr() – Extract or replace substrings.

7. Set Operations

union() – Union of two vectors.
intersect() – Intersection of two vectors.
setdiff() – Elements in one vector but not the other.
%in% – Check if elements are in another vector.

8. Other Useful Functions

sample() – Randomly sample elements from a vector.
match() – Find positions of first matches in a vector.
table() – Frequency table of vector elements.
cut() – Divide a continuous vector into intervals.