[R] Subtracting Data Frame With a Different Number of Rows

[Phillip Heinrich]

I have two small data frames of baseball data.  The first one is the mean 
number of runs that will score in each half inning for the 2018 Arizona 
Diamondbacks.  The second data frame is the same information but for only 
one player.  As you will see the individual player did not come up to bat 
any time during the season:
    with the bases loaded and no outs
    runners on first and third with one out

Overall

RunnerCode                Outs     MeanRuns
1 Bases Empty             0           0.5137615
2 Runner:1st                0           0.8967391
3 Runner:2nd               0           1.3018868
4 Runners:1st & 2nd    0           1.6551724
5 Runner:3rd                0           1.9545455
6 Runners:1st & 3rd     0           2.0571429
7 Runners:2nd & 3rd    0           2.1578947
8 Bases Loaded            0           3.2173913
9 Bases Empty              1           0.3963801
10 Runner:1st               1           0.6952596
11 Runner:2nd              1           0.9580838
12 Runners:1st & 2nd   1           1.4397163
13 Runner:3rd               1           1.5352113
14 Runners:1st & 3rd   1            1.5882353
15 Runners:2nd & 3rd  1            1.9215686
16 Bases Loaded          1            1.9193548
17 Bases Empty            2            0.4191011
18 Runner:1st               2            0.5531915
19 Runner:2nd              2            0.8777293
20 Runners:1st & 2nd  2             0.9553073
21 Runner:3rd              2             1.2783505
22 Runners:1st & 3rd   2             1.5851064
23 Runners:2nd & 3rd  2             1.2794118
24 Bases Loaded         2              1.388235

Individual Player

  RunnerCode              Outs           MeanRuns
1 Bases Empty             0                 0.4262295
2 Runner:1st                0                 1.3200000
3 Runner:2nd               0                 1.2857143
4 Runners:1st & 2nd   0                  0.5714286
5 Runner:3rd               0                  2.0000000
6 Runners:1st & 3rd    0                  3.5000000
7 Runners:2nd & 3rd   0                  1.0000000
8 Bases Empty             1                  0.5238095
9 Runner:1st                1                  0.6578947
10 Runner:2nd             1                  0.3750000
11 Runners:1st & 2nd 1                   1.4285714
12 Runner:3rd             1                   1.4285714
13 Runners:2nd & 3rd 1                   0.6666667
14 Bases Loaded         1                   3.0000000
15 Bases Empty           2                   0.3469388
16 Runner:1st              2                   0.1363636
17 Runner:2nd             2                   0.7142857
18 Runners:1st & 2nd  2                   1.6666667
19 Runner:3rd              2                   1.2500000
20 Runners:1st & 3rd  2                    2.1428571
21 Runners:2nd & 3rd 2                    1.5000000
22 Bases Loaded         2                    2.2000000

RunnersCode is a factor
Outs are integers
MeanRuns is numerical data

I would like to subtract the second from the first as a way to evaluate the 
players ability to produce runs. As part of this analysis I I would like to 
input the mean number of runs from the overall data frame into the two 
missing cells for the individual player:Bases Loaded no outs and 1st and 3rd 
one out.

Can anyone give me some advise?