SciencesPo (version 1.02.12)

shift: Lag or Lead Observations

Description

Shift function allows one to either lag or lead a column variables in a data frame.

Usage

shift(x, id, time, delta = 1)

Arguments

x

the variable to be lagged or leaded

id

the subject or identification variable.

time

the time id variable.

delta

an integer value (positive or negative) for units to move either backward or forward.

Value

• An object of the same type as x

encoding

UTF-8

Details

The combination of id and time must yelds to a unique identification of the observations.

Examples

data(sheston91)
# lag
sheston91$L.pop <- with(sheston91, shift(x = pop, id = country, time = year, delta = 1) )
head(sheston91)
# lead
 sheston91$pop.L <- with(sheston91, shift(x = pop, id = country, time = year, delta =  -1) )
 head(sheston91)