df = read.table(file = 'http://www.meteoprognoza.pl/Test/Polska10km/1/Sondaz_calosc.txt', header=F, stringsAsFactors = F)
head(df,40) # sprawdzenie czy plik dobrze sie wczytal
##            V1    V2    V3     V4     V5    V6
## 1  2016-10-31 godz.  18.0   dla: 54.75N 17.53
## 2      1019.1    29   8.5 -245.7     28  2.00
## 3      1000.0   187   7.6    3.1     20  4.00
## 4       975.0   393   5.8    2.3     20  4.00
## 5       950.0   603   3.8    1.8     19  4.00
## 6       925.0   822   1.8    0.9     15  4.00
## 7       900.0  1049   0.4   -1.5      5  4.00
## 8       875.0  1274  -0.8   -3.9    355  6.00
## 9       850.0  1505  -1.7   -4.9    349  8.00
## 10      825.0  1742  -2.3   -4.7    346 10.00
## 11      800.0  1951  -2.8   -4.0    344 13.00
## 12      775.0  2192  -3.3   -3.8    343 16.00
## 13      750.0  2487  -3.9   -4.3    342 18.00
## 14      725.0  2768  -4.5   -5.3    341 19.00
## 15      700.0  3044  -5.3   -6.5    343 21.00
## 16      675.0  3329  -6.2   -7.9    346 22.00
## 17      650.0  3625  -7.5   -9.4    348 24.00
## 18      625.0  3929  -9.0  -11.0    350 25.00
## 19      600.0  4244 -10.9  -13.1    350 25.00
## 20      575.0  4570 -12.9  -15.5    349 26.00
## 21      550.0  4907 -15.1  -18.1    349 27.00
## 22      525.0  5258 -17.3  -20.9    349 28.00
## 23      500.0  5621 -19.7  -24.1    349 29.00
## 24      475.0  6000 -22.3  -27.6    349 29.00
## 25      450.0  6396 -25.1  -31.2    349 30.00
## 26      425.0  6808 -28.3  -35.0    350 31.00
## 27      400.0  7239 -31.7  -38.4    350 32.00
## 28      375.0  7691 -35.3  -41.4    350 34.00
## 29      350.0  8168 -39.1  -44.5    348 37.00
## 30      325.0  8671 -43.1  -48.2    345 39.00
## 31      300.0  9205 -47.5  -52.4    343 41.00
## 32      275.0  9774 -52.2  -56.7    341 42.00
## 33      250.0 10383 -57.0  -61.5    342 43.00
## 34      225.0 11043 -60.9  -66.7    345 40.00
## 35      200.0 11771 -61.9  -71.3    343 33.00
## 36      150.0 13572 -56.2  -85.6    339 25.00
## 37      100.0 16134 -60.3  -84.1    344 17.00
## 38       50.0 20434 -61.9  -84.8    350 11.00
## 39 2016-10-31 godz.  19.0   dla: 54.75N 17.53
## 40     1019.0    29   9.2 -245.7     56  3.00
v <- which(df[,2]=='godz.') # poszukiwanie linii w pliku, ktore rozpoczynaja nowy 'sondaz'


system.time(b <- split(df, findInterval(1:nrow(df), v))) # rozdzielenie kazdego pomiaru do listy
##    user  system elapsed 
##  10.764   0.152  10.915
# przy okazji sprawdzenie czy konwersja nie jest zbyt obciazajaca...

b[[1]][-1,] # tylko wartosci dla pierwszego 'sondazu'
##        V1    V2    V3     V4  V5 V6
## 2  1019.1    29   8.5 -245.7  28  2
## 3  1000.0   187   7.6    3.1  20  4
## 4   975.0   393   5.8    2.3  20  4
## 5   950.0   603   3.8    1.8  19  4
## 6   925.0   822   1.8    0.9  15  4
## 7   900.0  1049   0.4   -1.5   5  4
## 8   875.0  1274  -0.8   -3.9 355  6
## 9   850.0  1505  -1.7   -4.9 349  8
## 10  825.0  1742  -2.3   -4.7 346 10
## 11  800.0  1951  -2.8   -4.0 344 13
## 12  775.0  2192  -3.3   -3.8 343 16
## 13  750.0  2487  -3.9   -4.3 342 18
## 14  725.0  2768  -4.5   -5.3 341 19
## 15  700.0  3044  -5.3   -6.5 343 21
## 16  675.0  3329  -6.2   -7.9 346 22
## 17  650.0  3625  -7.5   -9.4 348 24
## 18  625.0  3929  -9.0  -11.0 350 25
## 19  600.0  4244 -10.9  -13.1 350 25
## 20  575.0  4570 -12.9  -15.5 349 26
## 21  550.0  4907 -15.1  -18.1 349 27
## 22  525.0  5258 -17.3  -20.9 349 28
## 23  500.0  5621 -19.7  -24.1 349 29
## 24  475.0  6000 -22.3  -27.6 349 29
## 25  450.0  6396 -25.1  -31.2 349 30
## 26  425.0  6808 -28.3  -35.0 350 31
## 27  400.0  7239 -31.7  -38.4 350 32
## 28  375.0  7691 -35.3  -41.4 350 34
## 29  350.0  8168 -39.1  -44.5 348 37
## 30  325.0  8671 -43.1  -48.2 345 39
## 31  300.0  9205 -47.5  -52.4 343 41
## 32  275.0  9774 -52.2  -56.7 341 42
## 33  250.0 10383 -57.0  -61.5 342 43
## 34  225.0 11043 -60.9  -66.7 345 40
## 35  200.0 11771 -61.9  -71.3 343 33
## 36  150.0 13572 -56.2  -85.6 339 25
## 37  100.0 16134 -60.3  -84.1 344 17
## 38   50.0 20434 -61.9  -84.8 350 11
b[[1]][1,] # tylko metadane dla pierwszego pomiaru
##           V1    V2 V3   V4     V5    V6
## 1 2016-10-31 godz. 18 dla: 54.75N 17.53