I have a wide table with more than 22 columns. This table is the result of `fuzzymatch` and that's why it's in wide format. The column names are shown below (in order) (I will try to create a sample data frame for better demonstration):

```
 [1] "shift_date.x"  "shift"   "ageyrs"   "site"   "level"            
 [6] "crowded_shift"    "time"    "dd"     "AE"    "ageyrs_start"    
[11] "ageyrs_end"    "time_start"     "time_end"     "shift_date.y"     "shift_n"   
[16] "ageyrs_n"     "site_n"   "level_n"   "crowded_shift_n"  "los_n"           
[21] "dd_n" "AE_n" 

```

What I want to do is to break this data frame starting from column 14 to the end ("shift\_date.y" to "AE\_n") and add it as new rows to the bottom of first section of table (change it to long format). **The problem is** that the first section has 13 columns but the second part has 8 and I am not sure how I can combine them (that's why probably `subsetting` and `rbind` don't work).

As an example, imagine we have the following data frame:

```
shift <- c (2,1,0)
ageyrs <- c(12.2,13,14)
site <- c(0,1,3)
level <- c (1,5,6)
ageyrs_s <- c (2,4,5)
ageyrs_n <- c (4,6,8)
shift2 <- c (2,1,0)
ageyrs2 <- c(12.2,13,14)
site2 <- c(0,1,3)
level2 <- c (1,5,6)

a <- data.frame(shift, ageyrs, site, level, ageyrs_s, ageyrs2, shift2, ageyrs2, site2, level2)

  shift ageyrs site level ageyrs_s ageyrs_n shift_n ageyrs_n site_n level_n
1     2   12.2    0     1        2        4      2    12.2     0      1
2     1   13.0    1     5        4        6      1    13.0     1      5
3     0   14.0    3     6        5        8      0    14.0     3      6

```

No I want to break this dataframe at "shift2" column and create a dataframe line shown below:

```
 shift ageyrs site level ageyrs_s ageyrs_n
1     2   12.2    0     1        2        4
2     1   13.0    1     5        4        6
3     0   14.0    3     6        5        8
4     2   12.2    0     1       NA       NA
5     1   13.0    1     5       NA       NA
6     0   14.0    3     6       NA       NA

```

Any suggestions on how to resolve this?