R Language Reading and writing tabular data in plain-text files (CSV, TSV, etc.) Importing .csv files
Example
Importing using base R
Comma separated value files (CSVs) can be imported using read.csv, which wraps read.table, but uses sep = "," to set the delimiter to a comma.
# get the file path of a CSV included in R's utils package
csv_path <- system.file("misc", "exDIF.csv", package = "utils")
# path will vary based on installation location
csv_path
## [1] "/Library/Frameworks/R.framework/Resources/library/utils/misc/exDIF.csv"
df <- read.csv(csv_path)
df
## Var1 Var2
## 1 2.70 A
## 2 3.14 B
## 3 10.00 A
## 4 -7.00 A
A user friendly option, file.choose, allows to browse through the directories:
df <- read.csv(file.choose())
Notes
- Unlike
read.table,read.csvdefaults toheader = TRUE, and uses the first row as column names. - All these functions will convert strings to
factorclass by default unless eitheras.is = TRUEorstringsAsFactors = FALSE. - The
read.csv2variant defaults tosep = ";"anddec = ","for use on data from countries where the comma is used as a decimal point and the semicolon as a field separator.
Importing using packages
The readr package's read_csv function offers much faster performance, a progress bar for large files, and more popular default options than standard read.csv, including stringsAsFactors = FALSE.
library(readr)
df <- read_csv(csv_path)
df
## # A tibble: 4 x 2
## Var1 Var2
## <dbl> <chr>
## 1 2.70 A
## 2 3.14 B
## 3 10.00 A
## 4 -7.00 A
