Is it true that this is a matrix?
x y 1 1 A 2 2 B 3 3 C
No
because it is a collection of vectors of different types.
Is it true that this is a data frame?
x y 1 1 A 2 2 B 3 3 C
Yes
because it is a collection of vectors of different types.
Is it true that this is a data frame?
1 1 A 2 2 B 3 3 C
No,
because the vectors have no names.
Is it true that this is a data frame?
data.frame(x=c("1", "2", "3"), y=c("A", "B", "C"))
Yes
because it is a collection of named vectors.
Is it true that this is a data frame?
data.frame(c("1", "2", "3"),c("A", "B", "C"))
Yes
because it is a collection of named vectors -- with really ugly names:
c..1....2....3.. c..A....B....C.. 1 1 A 2 2 B 3 3 C
Is it true that this is a data frame?
beatles <- c("John", "Paul", "George", "Ringo")
destinyschild <- c("Beyonce", "Kelly", "Michelle")
data.frame(beatles, destinyschild)
No
because it is a collection of named vectors of unequal lengths.
Is it true that this is a data frame?
beatles <- c("John", "Paul", "George", "Ringo")
monkees <- c("Micky", "Michael", "Peter", "Davy")
data.frame(beatles, monkees)
Yes
because it is a collection of named vectors of equal length.
What is the value of bands$beatles where bands is
data.frame(beatles=c("John", "Paul", "George", "Ringo"), monkees=c("Micky", "Michael", "Peter", "Davy"))
[1] John Paul George Ringo
because those are the values of the vector named beatles.
What is the value of bands$Beatles where bands is
data.frame(beatles=c("John", "Paul", "George", "Ringo"), monkees=c("Micky", "Michael", "Peter", "Davy"))
NULL
because there is no vector named Beatles in bands.
What is the value of bands$Beatles where bands is
data.frame(beatles=c("John", "Paul", "George", "Ringo"), monkees=c("Micky", "Michael", "Peter", "Davy"))
NULL
because there is no vector named Beatles in bands.
Is it true that this is a data frame?
data.frame(data.frame(slayers=c("buffy", "faith", "kendra")), data.frame(scoobies=c("willow", "xander", "giles")))
yes
because it is a combination of two data frames.
Is it true that this is a data frame?
data.frame(data.frame(slayers=c("buffy", "faith", "kendra")), data.frame(scoobies=c("willow", "xander", "giles", "anya", "tara", "dawn")))
yes
although it may not look like you expect it to:
slayers scoobies 1 buffy willow 2 faith xander 3 kendra giles 4 buffy anya 5 faith tara 6 kendra dawn
Is it true that this is a data frame?
data.frame(data.frame(slayers=c("buffy", "faith", "kendra")), data.frame(scoobies=c("willow", "xander", "giles", "anya", "tara")))
no
because the data frame slayers and the data frame scoobies are of lengths that are not the same, nor is one evenly divisisble by the other.
Is it true that this is a data frame?
data.frame(capitols=c("Trenton", "Annapolis", "Sacramento"), representatives=c(12,8,53), bird=c("cardinal", "oriole", "quail"), row.names=c("New Jersey", "Maryland", "California"))
yes
because row names can be specified in data frames, though they do not have to be:
capitols representatives bird New Jersey Trenton 12 cardinal Maryland Annapolis 8 oriole California Sacramento 53 quail
What is states[3,] where states is
data.frame(capitols=c("Trenton", "Annapolis", "Sacramento"), representatives=c(12,8,53), bird=c("cardinal", "oriole", "quail"), row.names=c("New Jersey", "Maryland", "California"))
capitols representatives bird California Sacramento 53 quail
because California is the third row of states.
What is states["California",] where states is
data.frame(capitols=c("Trenton", "Annapolis", "Sacramento"), representatives=c(12,8,53), bird=c("cardinal", "oriole", "quail"), row.names=c("New Jersey", "Maryland", "California"))
capitols representatives bird California Sacramento 53 quail
because California is the specified row in states.
What is states["California",2] where states is
data.frame(capitols=c("Trenton", "Annapolis", "Sacramento"), representatives=c(12,8,53), bird=c("cardinal", "oriole", "quail"), row.names=c("New Jersey", "Maryland", "California"))
53
because California is the specified row in states, representatives is the second column in states, and 53 is the value in row California, column representatives.
Is is true that this creates a data frame?
who <- data.frame(doctors=c(1, 2, 3), actors=c("William Hartnell", "Patrick Troughton", "Jon Pertwee"))
who <- rbind(who, data.frame(doctors=4, actors="Tom Baker"))
yes
because rbind adds a row to a data frame.
What is who[5,2] when who is
who <- data.frame(doctors=c(1, 2, 3), actors=c("William Hartnell", "Patrick Troughton", "Jon Pertwee"))
who <- rbind(who, data.frame(doctors=4, actors="Tom Baker"), data.frame(doctors=5, actors="Peter Davison"))
Peter Davison
because the fifth row of who is
5 5 Peter Davison
and Peter Davison is the value in the second column.
Is is true that this creates a data frame?
who <- data.frame(doctors=c(1, 2, 3), actors=c("William Hartnell", "Patrick Troughton", "Jon Pertwee"))
who <- rbind(who, data.frame(doctors=4, played_by="Tom Baker"))
no
because the column names used do not match.
Is is true that this creates a data frame?
who <- data.frame(doctors=c(1, 2, 3), actors=c("William Hartnell", "Patrick Troughton", "Jon Pertwee"))
who <- cbind(who, start_year=c(1963, 1966, 1970))
yes
because cbind adds a column to a data frame.
Is is true that this creates a data frame?
who <- data.frame(doctors=c(1, 2, 3), actors=c("William Hartnell", "Patrick Troughton", "Jon Pertwee"))
who <- cbind(who, start_year=c(1963, 1966, 1970, 1974))
no
because all columns in a data frame must have the same number of rows.
Is is true that this creates a data frame?
who <- data.frame(doctors=c(1, 2, 3), actors=c("William Hartnell", "Patrick Troughton", "Jon Pertwee"))
who <- cbind(who, start_year=c(1963, 1966, 1970, 1974))
no
because all columns in a data frame must have the same number of rows.
Is is true that this creates a data frame?
who <- data.frame(doctors=c(1, 2, 3), actors=c("William Hartnell", "Patrick Troughton", "Jon Pertwee"), row.names=c("A", "B", "C"))
new_who <- data.frame(start_year=c(1963, 1966, 1970), row.names=c("I", "II", "III"))
whole_who <- cbind(who, new_who)
yes
because row names do not matter when combining data frames.