How To Make A Data Frame A Tbl In R

What is a Data Frame?

A data frame is a list of vectors which are of equal length. A matrix contains only one type of data, while a information frame accepts unlike data types (numeric, character, factor, etc.).

In this tutorial, you will learn-

What is a Data Frame?
How to Create a Information Frame
Suspend a Cavalcade to Data Frame
Select a Column of a Data Frame
Subset a Data Frame

How to Create a Data Frame

We can create a dataframe in R by passing the variable a,b,c,d into the data.frame() function. We can R create dataframe and name the columns with proper noun() and simply specify the name of the variables.

data.frame(df, stringsAsFactors = TRUE)

Arguments:

df: It can be a matrix to convert as a data frame or a drove of variables to join
stringsAsFactors: Catechumen cord to factor past default

We can create a dataframe in R for our beginning data set by combining four variables of same length.

# Create a, b, c, d variables a <- c(10,20,30,xl) b <- c('book', 'pen', 'textbook', 'pencil_case') c <- c(Truthful,Simulated,True,FALSE) d <- c(2.five, viii, 10, 7) # Join the variables to create a data frame df <- data.frame(a,b,c,d) df

Output:

##     a         b     c     d ## 1  10        book  True   ii.5 ## 2  twenty         pen  FALSE  8.0 ## iii  thirty    textbook  TRUE   x.0 ## 4  twoscore pencil_case  False  7.0

Nosotros can see the column headers have the same proper noun as the variables. We tin change column proper noun in R with the function names(). Check the R create dataframe example beneath:

# Name the data frame names(df) <- c('ID', 'items', 'store', 'cost') df

Output:

##   ID       items shop price ## one 10        volume  True   two.v ## two xx         pen Simulated   eight.0 ## iii thirty    textbook  TRUE  10.0 ## 4 40 pencil_case FALSE   7.0

# Print the construction str(df)

Output:

## 'information.frame':    4 obs. of  4 variables: ##  $ ID   : num  10 20 30 40 ##  $ items: Cistron w/ 4 levels "volume","pen","pencil_case",..: 1 2 4 3 ##  $ store: logi  True Simulated TRUE Imitation ##  $ price: num  2.v 8 10 seven

By default, data frame returns string variables as a factor.

Slice Data Frame

It is possible to Slice values of a Data Frame. We select the rows and columns to return into subclass precede by the name of the data frame.

A data frame is composed of rows and columns, df[A, B]. A represents the rows and B the columns. We can slice either by specifying the rows and/or columns.

From picture ane, the left part represents the rows, and the right role is the columns. Note that the symbol : means to. For instance, ane:3 intends to select values from one to 3.

Slice Data Frame

In below diagram we display how to access different selection of the information frame:

The yellow pointer selects the row 1 in column 2
The light-green arrow selects the rows i to 2
The red arrow selects the column 1
The bluish arrow selects the rows 1 to 3 and columns 3 to 4

Note that, if nosotros let the left part blank, R will select all the rows. By illustration, if we let the right office blank, R volition select all the columns.

Slice Data Frame

We can run the code in the console:

## Select row i in cavalcade two df[1,two]

Output:

## [i] book ## Levels: book pen pencil_case textbook

## Select Rows ane to ii df[one:2,]

Output:

##   ID items shop toll ## 1 10  book  TRUE   2.five ## 2 twenty   pen FALSE   viii.0

## Select Columns 1 df[,1]

Output:

## [i] x 20 30 40

## Select Rows 1 to 3 and columns three to 4 df[1:three, three:4]

Output:

##   store price ## i  TRUE   two.5 ## 2 Fake   8.0 ## 3  True  10.0

Information technology is also possible to select the columns with their names. For instance, the code below extracts two columns: ID and store.

# Slice with columns proper noun df[, c('ID', 'shop')]

Output:

##   ID store ## i ten  Truthful ## 2 20 Imitation ## 3 30  Truthful ## four 40 FALSE

Append a Cavalcade to Data Frame

Yous tin also append a column to a Data Frame. You lot demand to use the symbol $ to append dataframe R variable and add a column to a dataframe in R.

# Create a new vector quantity <- c(10, 35, 40, v)  # Add `quantity` to the `df` data frame df$quantity <- quantity df

Output:

##   ID       items store price quantity ## 1 10        book  TRUE   2.five       10 ## 2 xx         pen FALSE   8.0       35 ## 3 30    textbook  True  10.0       40 ## 4 40 pencil_case FALSE   7.0        5

Note: The number of elements in the vector has to be equal to the no of elements in data frame. Executing the post-obit statement to add column to dataframe R

quantity <- c(10, 35, twoscore) # Add `quantity` to the `df` data frame df$quantity <- quantity

Gives error:

Mistake in `

lt;-.data.frame`(`*tmp*`, quantity, value = c(10, 35, twoscore))
replacement has three rows, data has iv

Select a Column of a Data Frame

Sometimes, we need to store a cavalcade of a data frame for future employ or perform operation on a column. We can use the $ sign to select the column from a data frame.

# Select the column ID df$ID

Output:

## [1] 1 2 3 four

Subset a Information Frame

In the previous section, we selected an entire column without status. Information technology is possible to subset based on whether or not a certain status was true.

Nosotros use the subset() role.

subset(x, status) arguments: - x: data frame used to perform the subset - condition: define the conditional statement

We want to return only the items with price higher up 10, nosotros tin do:

# Select price above 5 subset(df, subset = price > five)

Output:

ID       items store price 2 20         pen Fake     eight 3 xxx    textbook  Truthful    x 4 xl pencil_case FALSE     7