tbl_df: Create a data frame tbl.

Description

A data frame tbl wraps a local data frame. The main advantage to using a tbl_df over a regular data frame is the printing: tbl objects only print a few rows and all the columns that fit on one screen, describing the rest of it as text.

Usage

tbl_df(data)

Arguments

data

a data frame

Methods

tbl_df implements two important base methods:

print: Only prints the first 10 rows, and the columns that fit on screen
[: Never simplifies (drops), so always returns data.frame

Examples

Run this code

ds <- tbl_df(mtcars)
ds
as.data.frame(ds)

if (require("Lahman") && packageVersion("Lahman") >= "3.0.1") {
batting <- tbl_df(Batting)
dim(batting)
colnames(batting)
head(batting)

# Data manipulation verbs ---------------------------------------------------
filter(batting, yearID > 2005, G > 130)
select(batting, playerID:lgID)
arrange(batting, playerID, desc(yearID))
summarise(batting, G = mean(G), n = n())
mutate(batting, rbi2 = if(is.null(AB)) 1.0 * R / AB else 0)

# Group by operations -------------------------------------------------------
# To perform operations by group, create a grouped object with group_by
players <- group_by(batting, playerID)
head(group_size(players), 100)

summarise(players, mean_g = mean(G), best_ab = max(AB))
best_year <- filter(players, AB == max(AB) | G == max(G))
progress <- mutate(players, cyear = yearID - min(yearID) + 1,
 rank(desc(AB)), cumsum(AB))

# When you group by multiple level, each summarise peels off one level
per_year <- group_by(batting, playerID, yearID)
stints <- summarise(per_year, stints = max(stint))
filter(stints, stints > 3)
summarise(stints, max(stints))
mutate(stints, cumsum(stints))


# Joins ---------------------------------------------------------------------
player_info <- select(tbl_df(Master), playerID, birthYear)
hof <- select(filter(tbl_df(HallOfFame), inducted == "Y"),
 playerID, votedBy, category)

# Match players and their hall of fame data
inner_join(player_info, hof)
# Keep all players, match hof data where available
left_join(player_info, hof)
# Find only players in hof
semi_join(player_info, hof)
# Find players not in hof
anti_join(player_info, hof)
}

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