= R File I/O =

There are distinct functions for reading or writing data files. 

<<TableOfContents>>

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== Native R ==

{{{
> df <- readRDS("data.rds")

> saveRDS(df, "data.rds")
}}}

Note that these functions are capable of reading/writing any R object to a file. As such, there cannot be a known type for the return value of `readRDS`.

Also note that the [[R/Readr|readr]] library provides wrappers around these functions named `read_rds` and `write_rds`. These are provided solely for naming consistency.

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== Text ==

The builtin functions `read.csv`, `read.delim`, and `read.table` can be used to read a text file as data. However, these functions are slower than the equivalents available from the [[R/Readr|readr]] library.

||'''Delimiter'''||'''Ingress Example'''                        ||'''Outgress Example'''                  ||
||Comma          ||`read_csv("data.csv")`                       ||`write_csv(df, "data.csv")`             ||
||Tab            ||`read_tsv("data.tsv")`                       ||`write_tsv(df, "data.tsv")`             ||
||Any character  ||`read_delim("data.txt", delim="|")`          ||`write_delim(df, "data.txt", delim="|")`||

For fixed width data, try:

{{{
> df <- read_fwf("data.txt", fwf_widths(c(2,2,NA)))
}}}

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== Stata ==

The [[R/Haven|haven]] library supports Stata versions 8-15.

{{{
> df <- read_dta("data.dta")

> write_dta(df, "data.dta")
}}}

Labels are frequently a problem for moving between Stata and R data formats, as the former does not support labels on decimal values. Use `zap_labels`, also provided by `haven`, to remove the offending value labels.

{{{
> df$foo <- zap_labels(df$foo)
}}}



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