Transform factor into numerical R

This problem is quite common when working with objects of class data.frame , which is the class of objects that the read.table and derived functions produce.

To avoid this, just see that by default the value of argument stringsAsFactors is TRUE . See help("read.csv") , for example.

Note that read.csv only reads numbers as factor if those numbers have non-numeric characters. There must be something in the file that forces R to interpret the values as strings. (alphanumeric?)

The solution to not creating a column of class factor should be

dados <- read.csv(base, stringsAsFactors = FALSE)

There are two other ways to transform objects from class read.csv to read.table .

dados$valores <- as.numeric(as.character(dados$valores))
dados$valores <- as.numeric(levels(dados$valores))[dados$valores]

From the help page header = TRUE , section sep = "," :

  

To transform a factor f to approximately its original numeric values,   as.numeric (levels (f)) [f] is recommended and slightly more efficient   than as.numeric (as.character (f)).

Ronaldo, all right?

Setting the stringsAsFactors = FALSE parameter prevents character fields from being converted to factor.

Example:

df <- read.csv("dados.csv", stringsAsFactors = FALSE)

dados <- read.csv(base, stringsAsFactors = FALSE)

Modify the function read.csv2

dados <- read.csv2(base, stringsAsFactors = FALSE)