I have some data which looks like:

```
                      08001              08003              08005              08006              08007              08009 08010_AM 08014_AM  0801501  0801502
08001    5637.485, 5167.354 22.21934, 21.98000 7.780077, 6.414000 8.225034, 8.383000          0.5526069 29.03881, 29.98300   16.015    7.431   11.691   17.307
08003    17.38138, 17.09300 3964.712, 3955.220   16.3736, 16.4790 50.98755, 49.40000 40.66504, 37.71000 134.9747, 133.2020     NULL   17.629  280.916  210.781
08005      5.78591, 3.80600 6.069553, 5.085000 2718.666, 2582.461 28.01711, 30.22900 25.80589, 26.65700 54.97441, 49.09300     NULL  344.551     NULL     NULL
08006    4.714246, 4.577000 60.72347, 55.27800 24.32941, 25.32800 11518.45, 12553.68 4770.038, 4885.562   204.825, 198.422     NULL    6.318   24.496   23.752
08007             0.5127518 53.37567, 49.76300 19.16522, 19.21800 4652.135, 4757.978 2958.100, 2915.518 125.4933, 105.3560     NULL     NULL    9.923   10.269
08009    22.39711, 22.06100 116.1297, 106.9830 58.20197, 52.02200 181.0659, 173.0710 93.77818, 75.02100 2870.151, 2813.574     NULL     NULL   19.905   36.054
08010_AM             22.794               NULL               NULL               NULL               NULL               NULL 2438.053   28.735     NULL     NULL
08014_AM              9.869               NULL             244.87             24.404               NULL             15.411   10.649   527.98     NULL    5.889
0801501              11.691            363.563               NULL             25.303              9.923             28.699     NULL     NULL 1626.898 4423.124
0801502              17.241            224.365              5.889             22.064             16.158             55.874     NULL   13.844 4581.857 2648.919

```

In some of the columns the data contains two results and in others just one result. I would like to map over the columns and unlist the listed columns and take an average of the two numbers in side them. Running:

```
d %>% 
  map_dbl(~mean(.x))

```

Gives NA's and doesn't do what I want.

Expected output (for the first 4 columns of row 1):

```
                      08001              08003              08005              08006
08001                5402.419          22.09967            7.097039           8.304017

```

Data:

```
d <- structure(list(`08001` = list(c(5637.485270141, 5167.354), c(17.381381281, 
17.093), c(5.785909683, 3.806), c(4.714246364, 4.577), 0.512751766, 
    c(22.397106858, 22.061), 22.794, 9.869, 11.691, 17.241), 
    `08003` = list(c(22.219343733, 21.98), c(3964.711783754, 
    3955.22), c(6.06955256, 5.085), c(60.723466947, 55.278), 
        c(53.375674504, 49.763), c(116.129671972, 106.983), NULL, 
        NULL, 363.563, 224.365), `08005` = list(c(7.780077106, 
    6.414), c(16.373600159, 16.479), c(2718.665550919, 2582.461
    ), c(24.329412615, 25.328), c(19.165216233, 19.218), c(58.201967855, 
    52.022), NULL, 244.87, NULL, 5.889), `08006` = list(c(8.225034053, 
    8.383), c(50.987554833, 49.4), c(28.017106028, 30.229), c(11518.451801321, 
    12553.676), c(4652.134976766, 4757.978), c(181.065902204, 
    173.071), NULL, 24.404, 25.303, 22.064), `08007` = list(0.552606869, 
        c(40.665035641, 37.71), c(25.805889186, 26.657), c(4770.038438613, 
        4885.562), c(2958.099855734, 2915.518), c(93.778183191, 
        75.021), NULL, NULL, 9.923, 16.158), `08009` = list(c(29.038810601, 
    29.983), c(134.974715164, 133.202), c(54.974411335, 49.093
    ), c(204.825009435, 198.422), c(125.493259667, 105.356), 
        c(2870.151467772, 2813.574), NULL, 15.411, 28.699, 55.874), 
    `08010_AM` = list(16.015, NULL, NULL, NULL, NULL, NULL, 2438.053, 
        10.649, NULL, NULL), `08014_AM` = list(7.431, 17.629, 
        344.551, 6.318, NULL, NULL, 28.735, 527.98, NULL, 13.844), 
    `0801501` = list(11.691, 280.916, NULL, 24.496, 9.923, 19.905, 
        NULL, NULL, 1626.898, 4581.857), `0801502` = list(17.307, 
        210.781, NULL, 23.752, 10.269, 36.054, NULL, 5.889, 4423.124, 
        2648.919)), row.names = c("08001", "08003", "08005", 
"08006", "08007", "08009", "08010_AM", "08014_AM", "0801501", 
"0801502"), class = "data.frame")

```