[R] Panel Data--filling in missing dates in a span only

[Adams, Jean]

Steve,

Here is one approach that works.  I am calling your first data frame "df".

# list all years from min to max observed in each ID
years <- tapply(df$Date, df$ID, function(x) min(x):max(x))

# create a data frame based on the observed range of years
fulldf <- data.frame(ID=rep(names(years), sapply(years, length)),
  Date=unlist(years))

# merge the data frame of observations with the data frame with all years
merge(fulldf, df, all=TRUE)

Jean

On Tue, Mar 10, 2015 at 5:53 PM, Steven Archambault <archstevej at gmail.com>
wrote:

> Hi folks,
>
> I have this panel data (below), with observations missing in each of the
> panels. I want to fill in years for the missing data, but only those years
> within the span of the existing data. For instance, BC-0002 needs on year,
> 1995. I do not want any years after the last observation.
>
> structure(list(ID = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L,
> 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), .Label =
> c("BC-0002",
> "BC-0003", "BC-0004"), class = "factor"), Date = c(1989L, 1990L,
> 1991L, 1992L, 1993L, 1994L, 1996L, 1989L, 1990L, 1991L, 1992L,
> 1993L, 1994L, 1996L, 1995L, 1996L, 1997L, 1998L, 2000L, 1994L,
> 1993L, 1999L, 1998L), DepthtoWater_bgs = c(317.85, 317.25, 321.25,
> 312.31, 313.01, 330.41, 321.01, 166.58, 167.55, 168.65, 168.95,
> 169.25, 168.85, 169.75, 260.6, 261.65, 262.15, 265.45, 266.15,
> 265.25, 265.05, 266.95, 267.75)), .Names = c("ID", "Date",
> "DepthtoWater_bgs"
> ), class = "data.frame", row.names = c(NA, -23L))
>
>
> I have been using this code to expand the entire panels, but it is not
> what exactly what I want.
>
> fexp <- expand.grid(ID=unique(wells$ID), Date=unique(wells$Date))
> merge(fexp, wells, all=TRUE)
>
> Any help would be much appreciated!
>
> Thanks,
> Steve
>
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>
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