[R] Repeat

[David Winsemius]

> On Feb 25, 2017, at 8:09 AM, Ashta <sewashm at gmail.com> wrote:
> 
> I have a data set and I want to repeat a column value based on other
> column value,
> 
> my data look like
> 
> read.table(text = "Year month flag
> 2001 1   Z
> 2001 2   -
> 2001 4   X
> 2002 1   Z
> 2002 2   -
> 2003 1   -
> 2003 2   Z
> 2004 2   Z
> 2005 3   Z
> 2005 2   -
> 2005 3   -",  header = TRUE)
> 
> Within year If  flag = '-'  then i want replace  '-'  by the previous
> row value of flag. In this example  for yea  2001 in month 2 flag is
> '-' and I want replace it by the previous value of flag (i.e.,  'Z')
> 2001 1   Z
> 2001 2   Z
> 2001 4   X
> 
> If all values of flag  are '-' within year  then  I wan to set as N
> 
> The complete out put result will be
> 
> year month  flag
> 2001 1       Z
> 2001 2       z
> 2001 4       X
> 2002 1       Z
> 2002 2       Z
> 2003 1       Z
> 2003 2       Z
> 2004 2       Z
> 2005 3       Z
> 2005 2       N
> 2005 3       N
> 
> Thank you in advance
> 

Your example doesn't actually match your verbal description of the algorithm because you have not specified the rule that establishes values for instances where the first value in a year is "-".

The `na.locf` function in the 'zoo' package would be useful for the task describe in your verbal description when used in conjunction with the 'stats'-package's `ave` function.

-- 
David.


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David Winsemius
Alameda, CA, USA