# extractors: Extract vectors by index or value occurrence In invctr: Infix Functions For Vector Operations

 extractors R Documentation

## Extract vectors by index or value occurrence

### Description

Extract front or rear of vector 'x' up and untill an index 'i', the first or last occurence of a value 'v', or, extract values based on quantile 'q', first, middle, or, last index 'j'.

### Usage

```x %[f% v

x %[l% v

x %[% i

x %]% i

x %f]% v

x %l]% v

x %q]% q

x %q)% q

x %[q% q

x %(q% q

x %:% j
```

### Arguments

 `x` A vector `v` A value of which the first or last occurrence in `x` will be used as an index `i` An index or two element vector `c(lo,hi)` indicating a range to extract `q` A percentile value (between '0' and '1') `j` A character indicating to extract the first 'f', middle 'm' or last 'l' value of 'x'.

### Value

A vector extracted from the front, rear, or, range of 'x'. Either based on an index or the first or last occurrence of a value or the first, middle, or, ;ast element of a vector.

### Note

The function provided for symmetry, character lengths of `x%]%i` and `x[1:i]` are equal.

### Examples

```
z <- letters

# Extract front by first occurrence of value
z %[f% "n"

# Extract front by index
x <- rnorm(100)
x %[% 10

# Extract rear by index
x %]% 90

# Extract rear by index
x %]% 90

# Extract by indices if a range is provided
x %]% c(4,30)
z %[% c(6,10)

# Extract last/middle value of x
x %:% "l"
z %:% "m"

# Extract by percentile
seq(1,10,.5) %(q% .5 # infix
seq(1,10,.5)[seq(1,10,.5) < quantile(seq(1,10,.5),.5)] # regular syntax

seq(1,10,.5) %q]% .5 # infix
seq(1,10,.5)[seq(1,10,.5) >= quantile(seq(1,10,.5),.5)] # regular syntax

```

invctr documentation built on Aug. 16, 2022, 5:18 p.m.