dataframe - trouble combining two numeric columns into one R -

so having bit of bother combining 2 columns one. have 2 columns of ages, split child , adolescent columns. example:

child adolescent 1   na  12 2   na  15 3   na  12 4   na  12 5   na  13 6   na  13 7   na  13 8   na  14 9   14  15 10  na  12 11  12  13 12  na  12 13  na  13 14  na  14 15  na  14 16  12  13 17  na  14 18  na  13 19  na  13 20  na  14 21  na  12 22  na  13 23  12  15 24  na  13 25  na  15 26  na  12 27  na  15 28  na  15 29  na  13 30  na  12 31  13  15` 

now combine them 1 column called "age" , remove na values. when try following code, encounter problem:

age<- c(na.omit(data$child),na.omit(data$adolescent)) 

the problem being original data has 514 rows, yet when combine 2 columns, removing nas, somehow end 543 values, not 514 , don't know why.

so, if possible, explain firstly why getting more values planned, , secondly might better way combine 2 columns.

edit: looking this

   age 1   12 2   15 3   12 4   12 5   13 6   13 7   13 8   14 9   14 10  12 11  12 12  12 13  13 14  14 15  14 16  12 17  14 18  13 19  13 20  14 21  12 22  13 23  12 24  13 25  15 26  12 27  15 28  15 29  13 30  12 31  13 32  14 33  13 34  11 35  15 36  13 

thanks in advance

this line:

age<- c(na.omit(data$child),na.omit(data$adolescent)) 

concatenates non-missing values child field non-missing values adolescent field. suspect want use 1 of these solutions

# youngest age age<- pmin(data$child,data$adolescent,na.rm=t)  # oldest age age<- pmax(data$child,data$adolescent,na.rm=t)  # child age, replaced adolescent if missing age<- data$child age[is.na(age)] <- data$adolescent[is.na(age)] #       ^   notice same logical index   ^ #       |_______________________________|