# [R] Data Checking

Sun Mar 24 12:26:39 CET 2002

```Ko-Kang Kevin Wang wrote:
>
> Hi,
>
> This is a simple question with if elseif....however I am having trouble
> constructing the solution for some reason.
>
> Suppose I have a data set with 3 variables, a, b and c say.  Let's say c
> is the sum of a and b.  So:
>   a  b  c
>   1  2  3
>   2  3  5
>   3  4  7
>   .  .  .
>   .  .  .
>   .  .  .
>
> Suppose that I know there have been some data entry errors and I want to
> check if ALL values in c is really the sum of a and b, and if not, print
> out the whole line (i.e. all values of a, b and c in that row).
>
> Any help on how I can write this if elseif block will be apprecaited!

Assume your "data set" is a data.frame():

X <- data.frame(a=1:5, b=2:6, ce=c(3,5,7,6,11))
# Let's call it a, b, ce --- c already is a function
# Now get the rows with errors:
X[X\$a + X\$b != X\$ce, ]

So you neither need the construct
if(condition){
statement
}
else{
statement2
}

nor
elseif(condition, statement1, statement2)

Uwe Ligges
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```