02. Datové objekty
Vít Gabrhel
R101
2019-09-29
Harmonogram
1. Vector
2. Factor
3. Data Frame
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Co je to objekt?
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Data
Data - FiveThirtvEight
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Vector
Vector
Vector je jednoduchý datový objekt o různé délce obsahující hodnoty.
c("Reservoir Dogs", "Pulp Fiction", "inglorious Basterds") ## [1] "Reservoir Dogs" "Pulp Fiction" "inglorious Basterds
c(421, 469, 51) ## [1] 421 469 51
c(421, "Reservoir Dogs", "death", false, 10)
## [1] "421" "Reservoir Dogs" "death" "false"
## [5] "10"
Vector
Vytvorenia pojmenování vektorového objektu
Počet cursing words dle filmů
Words_Movie = c(421, 469, 57, 51)
Co je co aneb pojmenování vektorů
names(words_Movie) = c("Reservoir Dogs",
"Pulp Fiction",
"Kill   Bill 1", "inglorious Basterds")
Vector
Výběr hodnot(y) z vektoru
Words_Movie[c(l, 4)]
## Reservoir Dogs inglorious Basterds
## 421 51
words_Movie[c("Reservoir Dogs", "inglorious Basterds")]
## Reservoir Dogs inglorious Basterds
## 421 51
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Vector
Vektorová aritmetika
Sčítání vektorů
Hell = c(12, 5, 3, 4) Goddamn = c(10, 28, 7, 8) Spirituality = Hell + Goddamn
Součet hodnot ve vektoru
words_N <- sum(Spi ritual i ty) words_N
## [1] 77
Vector
Logické operátory
< for less than
> for greater than
<= for less than or equal to
>= for greater than or equal to
== for equal to each other
!= not equal to each other
Ve kterých filmech padlo více cursing words, než byl jejich průměrný počet za filmů?
words_Movie > mean(Words_Movie)
## Reservoir Dogs Pulp Fiction Kill Bill 1
## TRUE TRUE FALSE
## inglorious Basterds
## FALSE
Vector
Logické operátory
names(Hell) = c("Reservoir Dogs", "Pulp Fiction",
"Kill Bill 1", "inglorious Basterds")
names(Goddamn) = c("Reservoir Dogs", "Pulp Fiction",
"Kill Bill 1", "inglorious Basterds")
Hell[c(l, 4)] > Goddamn[c(l, 4)]
## Reservoir Dogs inglorious Basterds
## TRUE FALSE
Hel1[c("Reservoir Dogs", "inglorious Basterds")] != Goddamn[c("Reservoir Dogs", "inglorious Basterds")]
## Reservoir Dogs inglorious Basterds
## TRUE TRUE
names(Spirituality) = c("Reservoir Dogs", "Pulp Fiction",
"Kill Bill 1", "inglorious Basterds")
Vector
Logické operátory
Klelo se v Pulp Fiction ve více než 50 případech?
Pul pFiction_Cel kern <- Spi ritual ity[c(2)] > 50 Pul pFi cti on_Celkem
## Pulp Fiction
## FALSE
Zaznívalo ve filmech více slovo "Hell" nebo "Goddamn"?
Hell < Goddamn
## Reservoir Dogs Pulp Fiction Kill Bill 1
## FALSE TRUE TRUE
## inglorious Basterds ## TRUE
Factor
Factor
Filmy = c("Kill Bill 1", "Reservoir Dogs", "inglorious Basterds", "Pulp Fiction") class(Filmy)
## [1] "character"
Nominální kategorie
Factor_Filmy = as.factor(Filmy) class(Factor_Fi1 my)
## [1] "factor"
levels(Factor_Filmy) <- c("Reservoir Dogs", "Pulp Fiction",
"Kill Bill 1", "inglorious Basterds")
Ordinalizace
Factor_Filmy <- factor(Filmy, order = TRUE,
levels = c("Reservoir Dogs", "Pulp Fiction",
"Kill Bill 1", "inglorious Basterds")
)
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Data Frame
Data Frame
Data Frame je matice tak, jak ji chápeme při analýze dat
• A data frame has the variables of a data set as columns and the observations as rows
O cursing words v Tar antinový ch filmech už něco víme. Co ale počet mrtvých?
Budeme se věnovat Pulp Fiction, Inglorious Basterds a Django Unchained spolu s počtem zesnulých postav. A Přidáme k tomu známý počet cursing words v příslušných filmech:
Pulp_Fiction = c(7, 469)
Inglořious_Basterds = c(48, 58)
Django_Unchained = c(47, 262)
Filmy <- data.frame(Pulp_Fiction, lnglorious_Basterds, Django_Unchained) view(Filmy) # otevře náhled na matici přimo v RStudio
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Data Frame
Manipulace s řádky/sloupci
col names(Filmy) <- c("Pulp Fiction", "inglorious Basterds", "Django Unchained")
rownames(Filmy) <- c("Deaths", "words")
view(Filmy)
rowSums(Filmy)
## Deaths words ##      102 789
col Sums(Filmy)
## Pulp Fiction inglorious Basterds      Django Unchained
## 476 106 309
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Data Frame
Jak do matice přidat sloupec / řádek?
• Skrze příkaz cbind() / rbind() Filmy si rozdělíme z hlediska období tvorby (90s, OOs a lOs) s kódy "0", "1" a "2":
Period = c(0, 1, 2)
Filmy_Period <- rbind(Filmy, Period)
rownames(Filmy_Period) <- c("Deaths", "words", "Period")
Jak příkazem zjistit aktivní objekty?
ls()
## [1] "Django_Unchained"
## [4] "Filmy_Period"
## [7] "lnglorious_Basterds
## [10] "PulpFiction_Celkern"
## [13] "words_N"
Factor_Filmy
Goddamn"
Period"
Spi ritual i ty
Filmy" Hell"
Pulp_Fi cti on words_Movie"
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Data Frame
Jak vybrat konkrétní prvky z matice?
• Similar to vectors, you can use the square brackets [ ] to select one or multiple elements from a data frame.
• Whereas vectors have one dimension, data frames have two dimensions. You should therefore use a comma to separate that what to select from the rows from that what you want to select from the columns. For example:
° Fi 1 my_Pe r i od [1, 2 ] selects the element at the first row and second column.
° Fi 1 my_Pe r i od [1: 3 ,2 : 3] results in a matrix with the data on the rows 1, 2, 3 and columns 2 and 3.
• If you want to select all elements of a row or a column, no number is needed before or after the comma, respectively:
° Fi 1 my_Pe r i od [, 1] selects all elements of the first column. ° Fi 1 my_Pe r i od [1, ] selects all elements of the first row.
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Data Frame
Jaký byl průměrný počet mrtvých ve sledovaných filmech?
Mean_Dead = as.numeric(Filmy_Period[l,]) mean(Mean_Dead)
## [1] 34
Jaký je Tarantino index (tj. počet mrtvých na počet nadávek) pro Inglorious Basterds?
Dead_Curse = data.frame(Filmy_Period[l:2,2]) Dead_Curse[2,l]/Dead_Curse[l,1]
## [1] 1.208333
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Intermezzo
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Data Frame
Vyvolání Data Frame z R
dataO
data(USArrests) view(liSArrests) ??USArrests
Jak se zorientovat v Data Frame?
head() # show the first observations of a data frame tail() # prints out the last observations in your data set str() # struktura dat
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Data Frame
Výběr z prvků
USArrests[l:3,3] USArrests[1:3,"UrbanPop"] USArrests$UrbanPop USArrests[l, "UrbanPop"]
Subsoubory
subset(USArrests, UrbanPop < 50)
Seřazování
order(USArrests$Murder)
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