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Juan Luis
Asked: 2020-03-29 03:40:06 +0800 CST 2020-03-29 03:40:06 +0800 CST

How to convert certain numeric variables of a dataframe to factor type in R?

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I have a dataframe that I have imported from an excel file, from which I select my variables of interest and introduce them in another dataframe:

datos_def <- read_excel("datos_def_excel")
datos_modelo <- subset(datos_def, select = c("SAP", "sexo", "edad","altura","peso", "niv_est","enf_cron","IMC","fuma", "sit_lab",
                                             "frec_act_fis","estrato","ingreso","ingreso_eq","GHQ_12","m2","n_adultos","n_menores",
                                            "ruido", "malos","agua","limpieza",
                                            "cont_indus", "cont_otras","escasez_verde", "molest_animal", "delincuencia"))

All the variables in this dataframe are of type numeric and there are some that I need to be of type factor, so I try the following:

variables_factor <- c("SAP","sexo","niv_est","enf_cron","fuma","sit_lab","frec_act_fis","estrato",
                     "ruido", "malos","agua","limpieza",
                     "cont_indus", "cont_otras","escasez_verde", "molest_animal", "delincuencia")

datos_modelo[,variables_factor] <- as.factor(datos_modelo[,variables_factor])

However, it returns me the following error:

Error: Must use a vector in `[`, not an object of class matrix.

r

1 Answers

  1. Best Answer

    I have not been able to reproduce the error, however you cannot apply it as.factor()the way you are doing it, you should do it on each column / variable separately:

    datos_modelo[, variables_factor] <- lapply(datos_modelo[, variables_factor], as.factor)
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