#
# a case study
#

## keep the school names with white spaces
dta <- read.csv("nzSchools.csv", as.is=2)

## Load & see data
str(dta)
## 'data.frame':    2571 obs. of  6 variables:
##  $ ID  : int  1015 1052 1062 1092 1130 1018 1029 1030 1588 1154 ...
##  $ Name: chr  "Hora Hora School" "Morningside School" "Onerahi School" "Raurimu Avenue School" ...
##  $ City: Factor w/ 541 levels "Ahaura","Ahipara",..: 533 533 533 533 533 533 533 533 533 533 ...
##  $ Auth: Factor w/ 4 levels "Other","Private",..: 3 3 3 3 3 3 3 3 4 3 ...
##  $ Dec : int  2 3 4 2 4 8 5 5 6 1 ...
##  $ Roll: int  318 200 455 86 577 329 637 395 438 201 ...
##check the data dimension
dim(dta)
## [1] 2571    6
## binning

##Conditional execution,If dta$Rolls' value greater than median(Roll),then value is regarded as "Large", if not, it is regarded as "Small" . Define Size in dta by column.
dta$Size <- ifelse(dta$Roll > median(dta$Roll), "Large", "Small")

##As shown below
head(dta)
##     ID                  Name      City  Auth Dec Roll  Size
## 1 1015      Hora Hora School Whangarei State   2  318 Large
## 2 1052    Morningside School Whangarei State   3  200 Large
## 3 1062        Onerahi School Whangarei State   4  455 Large
## 4 1092 Raurimu Avenue School Whangarei State   2   86 Small
## 5 1130      Whangarei School Whangarei State   4  577 Large
## 6 1018       Hurupaki School Whangarei State   8  329 Large
##empty size out of the dta
dta$Size <- NULL

##As shown below
head(dta)
##     ID                  Name      City  Auth Dec Roll
## 1 1015      Hora Hora School Whangarei State   2  318
## 2 1052    Morningside School Whangarei State   3  200
## 3 1062        Onerahi School Whangarei State   4  455
## 4 1092 Raurimu Avenue School Whangarei State   2   86
## 5 1130      Whangarei School Whangarei State   4  577
## 6 1018       Hurupaki School Whangarei State   8  329
##cut Roll with three level,which are "Small", "Mediam" and "Large". Define Size in the dta.
dta$Size <- cut(dta$Roll, 3, labels=c("Small", "Mediam", "Large"))

##As shown below by table(# of size level)
table(dta$Size)
## 
##  Small Mediam  Large 
##   2555     15      1
## sorting

##Sort Roll by decline,add the RollOrd column by Roll position
dta$RollOrd <- order(dta$Roll, decreasing=T)

##reveal the top six by Roll
head(dta[dta$RollOrd, ])
##       ID                  Name         City  Auth Dec Roll   Size RollOrd
## 1726 498 Correspondence School   Wellington State  NA 5546  Large     753
## 301   28     Rangitoto College     Auckland State  10 3022 Mediam     353
## 376   78      Avondale College     Auckland State   4 2613 Mediam     712
## 2307 319  Burnside High School Christchurch State   8 2588 Mediam     709
## 615   41      Macleans College     Auckland State  10 2476 Mediam    1915
## 199   43    Massey High School     Auckland State   5 2452 Mediam    1683
##Display the last six by Roll
tail(dta[dta$RollOrd, ])
##        ID                    Name                  City    Auth Dec Roll  Size
## 2401 1641  Amana Christian School               Dunedin Private   9    7 Small
## 1590 2461       Tangimoana School              Manawatu   State   4    6 Small
## 1996 3598         Woodbank School              Kaikoura   State   4    6 Small
## 2112 3386     Jacobs River School          Jacobs River   State   5    6 Small
## 1514 2407     Ngamatapouri School Sth Taranaki District   State   9    5 Small
## 1575 2420 Papanui Junction School               Taihape   State   5    5 Small
##      RollOrd
## 2401    2562
## 1590     266
## 1996    2478
## 2112    1501
## 1514    2377
## 1575    1542
##First,Sort the data according to City and Roll

##Second,sort the city's English name from Z to A in descending order
##Third,Display the top six by City and Roll
head(dta[order(dta$City, dta$Roll, decreasing=T), ])
##        ID                      Name      City  Auth Dec Roll  Size RollOrd
## 2548  401           Menzies College   Wyndham State   4  356 Small     859
## 2549 4054            Wyndham School   Wyndham State   5   94 Small    1163
## 1611 2742          Woodville School Woodville State   3  147 Small     726
## 1630 2640           Papatawa School Woodville State   7   27 Small    2273
## 2041 3600            Woodend School   Woodend State   9  375 Small    1401
## 1601  399 Central Southland College    Winton State   7  549 Small     450
##Display the last six by City and Roll
tail(dta[order(dta$City, dta$Roll, decreasing=T), ])
##        ID                         Name    City  Auth Dec Roll  Size RollOrd
## 2169 3273                Albury School  Albury State   8   30 Small    1010
## 2018  350           Akaroa Area School  Akaroa State   8  125 Small    1051
## 2023 3332           Duvauchelle School  Akaroa State   9   41 Small     749
## 335  1200                Ahuroa School  Ahuroa State   7   22 Small     193
## 99   1000               Ahipara School Ahipara State   3  241 Small    1963
## 2117 2105 Awahono School - Grey Valley  Ahaura State   4  119 Small     364
## counting

##compute number of Auths' classification
table(dta$Auth)
## 
##            Other          Private            State State Integrated 
##                1               99             2144              327
##Define authtbl
authtbl <- table(dta$Auth); authtbl
## 
##            Other          Private            State State Integrated 
##                1               99             2144              327
##what type of authtbl?
class(authtbl)
## [1] "table"
##find dta$Auth = "Other" and see it
dta[dta$Auth == "Other", ]
##       ID            Name         City  Auth Dec Roll  Size RollOrd
## 2315 518 Kingslea School Christchurch Other   1   51 Small    1579
##Contingency table by Auth and Dec
xtabs(~ Auth + Dec, data=dta)
##                   Dec
## Auth                 1   2   3   4   5   6   7   8   9  10
##   Other              1   0   0   0   0   0   0   0   0   0
##   Private            0   0   2   6   2   2   6  11  12  38
##   State            259 230 208 219 214 215 188 200 205 205
##   State Integrated  12  22  35  28  38  34  45  45  37  31
## aggregating

##compute Roll mean
mean(dta$Roll)
## [1] 295.4737
##select the dta of "Auth = "Private"" ,and comptute the mean of Roll.
mean(dta$Roll[dta$Auth == "Private"])
## [1] 308.798
##Calculate the Rolls'average for each group by Auth

aggregate(dta["Roll"], by=list(dta$Auth), FUN=mean)
##            Group.1     Roll
## 1            Other  51.0000
## 2          Private 308.7980
## 3            State 300.6301
## 4 State Integrated 258.3792
##Add Rich variable based on Dec > 5 condition
dta$Rich <- dta$Dec > 5; dta$Rich
##    [1] FALSE FALSE FALSE FALSE FALSE  TRUE FALSE FALSE  TRUE FALSE FALSE FALSE
##   [13] FALSE FALSE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE FALSE  TRUE  TRUE
##   [25] FALSE FALSE FALSE FALSE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE
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##  [409]  TRUE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
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##  [433] FALSE  TRUE FALSE FALSE FALSE  TRUE FALSE FALSE FALSE  TRUE  TRUE  TRUE
##  [445]  TRUE FALSE  TRUE  TRUE FALSE    NA  TRUE  TRUE FALSE  TRUE FALSE FALSE
##  [457]  TRUE  TRUE FALSE  TRUE  TRUE    NA  TRUE FALSE    NA  TRUE  TRUE FALSE
##  [469]  TRUE    NA FALSE  TRUE  TRUE FALSE  TRUE FALSE    NA  TRUE FALSE  TRUE
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## [1681]  TRUE  TRUE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE
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## [1729]  TRUE FALSE    NA FALSE FALSE FALSE  TRUE  TRUE  TRUE    NA FALSE FALSE
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## [1789] FALSE  TRUE FALSE FALSE FALSE FALSE  TRUE FALSE  TRUE  TRUE  TRUE    NA
## [1801]  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE FALSE FALSE
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## [1885]  TRUE  TRUE  TRUE FALSE  TRUE    NA  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
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## [1933]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE FALSE
## [1945] FALSE FALSE FALSE FALSE  TRUE FALSE  TRUE FALSE FALSE  TRUE  TRUE  TRUE
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## [1969] FALSE  TRUE  TRUE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE
## [1981]  TRUE FALSE  TRUE FALSE  TRUE FALSE  TRUE  TRUE FALSE FALSE  TRUE  TRUE
## [1993]  TRUE FALSE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE
## [2005]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2017]  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE
## [2029]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE  TRUE
## [2041]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2053]  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2065]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE FALSE  TRUE  TRUE  TRUE
## [2077]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2089]  TRUE FALSE FALSE FALSE FALSE  TRUE FALSE  TRUE FALSE FALSE  TRUE FALSE
## [2101]  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE    NA FALSE FALSE
## [2113] FALSE  TRUE  TRUE  TRUE FALSE  TRUE FALSE FALSE FALSE  TRUE FALSE FALSE
## [2125]  TRUE FALSE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE FALSE FALSE
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## [2173] FALSE  TRUE FALSE FALSE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
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## [2281]  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE
## [2293] FALSE  TRUE FALSE  TRUE FALSE FALSE FALSE FALSE  TRUE FALSE  TRUE  TRUE
## [2305]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE
## [2317]  TRUE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE FALSE FALSE  TRUE
## [2329]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE
## [2341]  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE
## [2353]  TRUE FALSE FALSE  TRUE FALSE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE FALSE
## [2365]  TRUE  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2377]  TRUE  TRUE FALSE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE
## [2389]  TRUE  TRUE  TRUE  TRUE FALSE  TRUE FALSE  TRUE  TRUE FALSE  TRUE  TRUE
## [2401]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2413]  TRUE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE FALSE
## [2425]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2437]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2449]  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2461]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE FALSE FALSE  TRUE
## [2473]  TRUE FALSE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2485]  TRUE  TRUE FALSE FALSE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE
## [2497]  TRUE FALSE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2509]  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2521]  TRUE FALSE FALSE FALSE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE
## [2533]  TRUE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE
## [2545] FALSE FALSE  TRUE FALSE FALSE FALSE  TRUE FALSE  TRUE  TRUE FALSE  TRUE
## [2557] FALSE  TRUE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE  TRUE
## [2569] FALSE  TRUE  TRUE
##compute the Rolls' mean by the grop of Auth and Rich
aggregate(dta["Roll"], by=list(dta$Auth, dta$Rich), FUN=mean)
##            Group.1 Group.2     Roll
## 1            Other   FALSE  51.0000
## 2          Private   FALSE 151.4000
## 3            State   FALSE 261.7487
## 4 State Integrated   FALSE 183.2370
## 5          Private    TRUE 402.5362
## 6            State    TRUE 338.8243
## 7 State Integrated    TRUE 311.2135
##compute the range of Roll by Auth
by(dta["Roll"], INDICES=list(dta$Auth), FUN=range)
## : Other
## [1] 51 51
## ------------------------------------------------------------ 
## : Private
## [1]    7 1663
## ------------------------------------------------------------ 
## : State
## [1]    5 5546
## ------------------------------------------------------------ 
## : State Integrated
## [1]   18 1475
##Another alternative code to perform the same calculation where appropriate!
aggregate(dta["Roll"], by=list(dta$Auth), FUN=range)
##            Group.1 Roll.1 Roll.2
## 1            Other     51     51
## 2          Private      7   1663
## 3            State      5   5546
## 4 State Integrated     18   1475
###