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Columns Accessors | Data Frames
R Introduction: Part II

bookColumns Accessors

Since data frames have names on their columns, you should be able to extract necessary data using them.

There are several ways in R to refer to a particular column using naming. One of them is the same as in vectors and matrices: column name within square brackets (for example, data[, "col_name"]). The second way is unique for data frames - using the dollar $ sign. The syntax is data$col_name (yes, without quotation marks). For example, you can extract the column "Age" from the data frame created in the last chapter.

# Data
name <- c("Alex", "Julia", "Finn")
age <- c(24, 43, 32)
gender <- c("M", "F", "M")
# Creating a data frame
test <- data.frame(name, age, gender)

# Extracting the name column using two ways
test[,"name"]
test$name
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# Data name <- c("Alex", "Julia", "Finn") age <- c(24, 43, 32) gender <- c("M", "F", "M") # Creating a data frame test <- data.frame(name, age, gender) # Extracting the name column using two ways test[,"name"] test$name
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test

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Let's work with the mtcars dataset. Your tasks are:

  1. Extract the cyl column values using square brackets.
  2. Extract the disp column values using the dollar $ sign.

¿Todo estuvo claro?

¿Cómo podemos mejorarlo?

¡Gracias por tus comentarios!

Sección 2. Capítulo 3
# Use square brackets
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# Use dollar sign
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