What are R levels?

Question

I am trying to read a csv file with R. I can read the file but I have levels when I call a variable. What are these levels and how can I remove them? The file can be downloaded here file ``` > data=read.csv("Documents/bet/I1.csv",sep=",") > data$HomeTeam [1] Sampdoria Verona Cagliari Inter Lazio Livorno Napoli Parma [9] Torino Fiorentina Chievo Juventus Atalanta Bologna Catania Genoa [17] Milan Roma Sassuolo Udinese Inter Napoli Torino Fiorentina [25] Lazio Livorno Sampdoria Udinese Verona Parma Cagliari Chievo [33] Genoa Atalanta Bologna Catania Juventus Milan Roma Sassuolo [41] Udinese Bologna Chievo Lazio Livorno Napoli Parma Sampdoria [49] Torino Inter Genoa Milan Atalanta Cagliari Catania Roma [57] Sassuolo Torino Verona Fiorentina Bologna Catania Napoli Parma [65] Sampdoria Udinese Juventus Lazio Chievo Inter Roma Cagliari [73] Milan Atalanta Fiorentina Genoa Livorno Sassuolo Verona Torino [81] Inter Sampdoria Bologna Catania Chievo Juventus Lazio Napoli [89] Parma Udinese Atala…

Accepted Answer

When you use ?read.csv to read a file, the argument `stringsAsFactors` is set by default to `TRUE`, you just need to set it to false to not get this result. This should work:

```
data = read.csv("Documents/bet/I1.csv", sep=",", stringsAsFactors=FALSE)
```

Under the default, columns (variables) in the file that contain strings are assumed to be factors. A factor is a categorical variable that can take only one of a fixed, finite set of possibilities. Those possible categories are the levels. You can read about factors in the R Intro manual here, and this is another tutorial.

In addition, since you are using read.csv, adding the `sep=","` is redundant. It doesn't harm anything, but the comma is taken as the separator by default.

What are R levels?

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