Importing Data File

To read in tabular data (e.g., .txt file), use read.table().

data <- read.table("path/datafile.txt", header = T, sep = "\t")  # set working directory

* Run ?read.table to see specific arguments in the function

If data is in .csv format, use read.csv().

data <- read.csv("path/datafile.csv", header = T)  

To import data in other formats (such as SPSS data files), use functions in foreign package.

library(foreign)
data <- read.spss("D://Box Sync/2020Fall/EP762_TA/examples/762-3 two groups.sav", to.data.frame = T)   

After importing the data file, you can check whether you have correctly read in the data. Below are some example functions to use.

head(data)      # first 6 rows of the data

##   method score
## 1      1    35
## 2      1    23
## 3      1    14
## 4      1    17
## 5      1    23
## 6      1    35

data[1:10, ]    # extract the first 10 rows 

##    method score
## 1       1    35
## 2       1    23
## 3       1    14
## 4       1    17
## 5       1    23
## 6       1    35
## 7       1    27
## 8       1    33
## 9       1    32
## 10      1    31

tail(data)      # last 6 rows of the data

##    method score
## 15      2    39
## 16      2    45
## 17      2    31
## 18      2    40
## 19      2    25
## 20      2    32

str(data)       # structure of thedata frame

## 'data.frame':	20 obs. of  2 variables:
##  $ method: num  1 1 1 1 1 1 1 1 1 1 ...
##  $ score : num  35 23 14 17 23 35 27 33 32 31 ...

summary(data)   # summary of data

##      method        score      
##  Min.   :1.0   Min.   :14.00  
##  1st Qu.:1.0   1st Qu.:26.50  
##  Median :1.5   Median :32.00  
##  Mean   :1.5   Mean   :31.50  
##  3rd Qu.:2.0   3rd Qu.:35.25  
##  Max.   :2.0   Max.   :51.00

attributes(data)  # attributes of object

## $names
## [1] "method" "score" 
## 
## $class
## [1] "data.frame"
## 
## $row.names
##  [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20

names(data)  # variable names

## [1] "method" "score"

dim(data)    # dimension of data (number of rows and columns)

## [1] 20  2

dimnames(data)   # row and column names

## [[1]]
##  [1] "1"  "2"  "3"  "4"  "5"  "6"  "7"  "8"  "9"  "10" "11" "12" "13" "14" "15"
## [16] "16" "17" "18" "19" "20"
## 
## [[2]]
## [1] "method" "score"

nrow(data)   # number of rows

## [1] 20

ncol(data)   # number of columns

## [1] 2

class(data)  # class of object

## [1] "data.frame"