Read in the data using fread

library(data.table)
library(ggplot2)
library(magrittr)
temp = fread("Temperature.csv")

Extract all winter observations

winterTemp = temp[Season == "winter"]
head(winterTemp)
##           Sample     Date     DateNr dDay1 dDay2 dDay3 Station   Area 31UE_ED50
##           <char>    <int>     <char> <int> <int> <int>  <char> <char>     <num>
## 1: DANT.19900110 19900110    10/1/90     7     9     9    DANT     WZ  681379.6
## 2: DANT.19900206 19900206     6/2/90    34    36    36    DANT     WZ  681379.6
## 3: DANT.19901212 19901212   12/12/90   343   345   345    DANT     WZ  681379.6
## 4: DANT.19910116 19910116  1/16/1991   378   380    15    DANT     WZ  681379.6
## 5: DANT.19910226 19910226  2/26/1991   419   421    56    DANT     WZ  681379.6
## 6: DANT.19911219 19911219 12/19/1991   715   717   352    DANT     WZ  681379.6
##    31UN_ED50  Year Month Season Salinity Temperature CHLFa
##        <num> <int> <int> <char>    <num>       <num> <num>
## 1:   5920571  1990     1 winter    29.19         4.0  1.30
## 2:   5920571  1990     2 winter    27.37         6.0    NA
## 3:   5920571  1990    12 winter    31.50         4.2 60.50
## 4:   5920571  1991     1 winter    20.83        -0.3  2.30
## 5:   5920571  1991     2 winter    28.06         3.9  3.52
## 6:   5920571  1991    12 winter    25.31         3.9  3.50

Extract all winter observations for zone NC

winterNC = temp[Season == "winter" & Area == "NC"]
head(winterNC)
##           Sample     Date     DateNr dDay1 dDay2 dDay3 Station   Area 31UE_ED50
##           <char>    <int>     <char> <int> <int> <int>  <char> <char>     <num>
## 1: T100.19900103 19900103     3/1/90     0     2     2    T100     NC  587650.2
## 2: T100.19900205 19900205     5/2/90    33    35    35    T100     NC  587650.2
## 3: T100.19901218 19901218 12/18/1990   349   351   351    T100     NC  587650.2
## 4: T100.19910116 19910116  1/16/1991   378   380    15    T100     NC  587650.2
## 5: T100.19910205 19910205     5/2/91   398   400    35    T100     NC  587650.2
## 6: T100.19911211 19911211   11/12/91   707   709   344    T100     NC  587650.2
##    31UN_ED50  Year Month Season Salinity Temperature CHLFa
##        <num> <int> <int> <char>    <num>       <num> <num>
## 1:   6001110  1990     1 winter    34.82         8.5  0.30
## 2:   6001110  1990     2 winter       NA          NA    NA
## 3:   6001110  1990    12 winter    34.80         9.2  0.40
## 4:   6001110  1991     1 winter    34.86         6.1  0.68
## 5:   6001110  1991     2 winter    34.53         5.2  0.34
## 6:   6001110  1991    12 winter    34.79         9.7  0.44

Select only the columns “Area”, “Season” and “Temperature”

AreaSeasTemp = temp[, .(Area, Season, Temperature)]
AreaSeasTemp
##         Area Season Temperature
##       <char> <char>       <num>
##    1:     WZ winter        4.00
##    2:     WZ winter        6.00
##    3:     WZ spring        7.30
##    4:     WZ spring        8.20
##    5:     WZ spring       17.40
##   ---                          
## 8524:     WZ autumn       15.47
## 8525:     WZ autumn       13.45
## 8526:     WZ autumn       12.09
## 8527:     WZ autumn        9.03
## 8528:     WZ winter        5.13

Select only the columns “Area” and “Temperature” but only for winter observations

winterAreaTemp = temp[Season == "winter", .(Area, Temperature)]
winterAreaTemp
##         Area Temperature
##       <char>       <num>
##    1:     WZ        4.00
##    2:     WZ        6.00
##    3:     WZ        4.20
##    4:     WZ       -0.30
##    5:     WZ        3.90
##   ---                   
## 1702:     WZ        4.40
## 1703:     WZ        4.72
## 1704:     WZ        3.57
## 1705:     WZ        1.31
## 1706:     WZ        5.13

Find the total number of observations in winter

winterObs = temp[Season == "winter", .N]
winterObs
## [1] 1706

Calculate the mean temperature and mean salinity in winter

winterMean = temp[Season == "winter", 
                  .(m_temp = mean(Temperature, na.rm = TRUE), m_salinity = mean(Salinity, na.rm = TRUE))]
winterMean
##     m_temp m_salinity
##      <num>      <num>
## 1: 5.57162   29.15756

Find the number of observations per station in winter

stationWinter = temp[Season == "winter", .N, by = Station]
stationWinter
##     Station     N
##      <char> <int>
##  1:    DANT    50
##  2:    DREI    52
##  3:      G6   101
##  4:    GROO    50
##  5:    HAMM    55
##  6:    HANS    56
##  7:    HUIB    50
##  8:    LODS    54
##  9:    MARS    49
## 10:     N02   115
## 11:     N10   131
## 12:     N20    50
## 13:     N70    50
## 14:     R03    32
## 15:    SOEL    50
## 16:    T004    97
## 17:    T010    45
## 18:    T100    45
## 19:    T135    46
## 20:    T175    45
## 21:    T235    45
## 22:    VLIS    84
## 23:     W02    99
## 24:     W20    47
## 25:     W70    47
## 26:    WISS    55
## 27:    ZIJP    54
## 28:    ZUID    52
##     Station     N

Find the number of observations per station per season

stationSeason = temp[, .N, by = .(Station, Season)]
stationSeason
##      Station Season     N
##       <char> <char> <int>
##   1:    DANT winter    50
##   2:    DANT spring    89
##   3:    DANT summer    89
##   4:    DANT autumn    72
##   5:    DREI winter    52
##  ---                     
## 114:    ZIJP autumn    61
## 115:    ZUID winter    52
## 116:    ZUID spring    89
## 117:    ZUID summer    89
## 118:    ZUID autumn    73

Estimate average temperatures by month

avgTempMonth = temp[,.(m_temp = mean(Temperature, na.rm = TRUE)), by = .(Month)]
avgTempMonth
##     Month    m_temp
##     <int>     <num>
##  1:     1  5.174210
##  2:     2  4.737400
##  3:     3  6.125961
##  4:     4  8.702035
##  5:     5 12.293479
##  6:     6 15.659933
##  7:     7 18.077343
##  8:     8 19.388355
##  9:     9 16.995974
## 10:    10 13.619670
## 11:    11  9.848891
## 12:    12  6.746339

Estimate average temperatures by month by area

avgTempMonthArea = temp[,.(m_temp = mean(Temperature, na.rm = TRUE)), by = .(Month, Area)]
avgTempMonthArea
##      Month   Area    m_temp
##      <int> <char>     <num>
##   1:     1     WZ  3.377826
##   2:     2     WZ  3.925800
##   3:     3     WZ  5.818481
##   4:     4     WZ  9.270805
##   5:     5     WZ 13.398191
##  ---                       
## 116:     1     NC  6.789808
## 117:     2     NC  5.682581
## 118:     3     NC  5.837500
## 119:    11     NC 10.978269
## 120:    12     NC  8.716957

Plot the output of the previous question using ggplot2 using the geom_line() geometry

ggplot(avgTempMonthArea, aes(x = Month, y = m_temp, col = Area)) + geom_line()