May 12, 2021 R language tutorial
A binary is a file that contains information stored only in bits and bytes (0 and 1). T hey are not human readable because the bytes in it are converted to characters and symbols that contain many other non-printable characters. T rying to read a binary using any text editor will display characters such as O and .
The binary must be read by a specific program to be used. F or example, a Microsoft Word program's binary can only be read in human readable form through a Word program. T his means that in addition to human-readable text, there is more information, such as the formatting of characters and page numbers, which are stored with alphanumeric characters. T he last binary is a continuous sequence of bytes. T he line breaks we see in the text file are characters that connect the first line to the next line.
Sometimes, data generated by other programs needs to be processed by R as a binary. I n addition, the R language is required to create binary files that can be shared with other programs.
The R language has two functions, WhiteBin() and readBin(), to create and read bins.
writeBin(object, con) readBin(con, what, n )
The following is a description of the parameters used -
con is a connection object that reads or writes binary files.
Object is the binary to write to.
What - like characters, integers, etc. that represent byte mode being read.
n The number of bytes read from the binary.
Let's consider the R language built-in data "mtcars". F irst, we create a csv file from it, convert it to a binary file, and store it as an operating system file. Next we read this created binary.
We read the data frame "mtcars" as a csv file and write it to the operating system as a binary.
# Read the "mtcars" data frame as a csv file and store only the columns
"cyl", "am" and "gear".
write.table(mtcars, file = "mtcars.csv",row.names = FALSE, na = "",
col.names = TRUE, sep = ",")
# Store 5 records from the csv file as a new data frame.
new.mtcars <- read.table("mtcars.csv",sep = ",",header = TRUE,nrows = 5)
# Create a connection object to write the binary file using mode "wb".
write.filename = file("/web/com/binmtcars.dat", "wb")
# Write the column names of the data frame to the connection object.
writeBin(colnames(new.mtcars), write.filename)
# Write the records in each of the column to the file.
writeBin(c(new.mtcars$cyl,new.mtcars$am,new.mtcars$gear), write.filename)
# Close the file for writing so that it can be read by other program.
close(write.filename)
The binary created above stores all the data as consecutive bytes. T herefore, we will read it by selecting the appropriate column name value and column value.
# Create a connection object to read the file in binary mode using "rb".
read.filename <- file("/web/com/binmtcars.dat", "rb")
# First read the column names. n = 3 as we have 3 columns.
column.names <- readBin(read.filename, character(), n = 3)
# Next read the column values. n = 18 as we have 3 column names and 15 values.
read.filename <- file("/web/com/binmtcars.dat", "rb")
bindata <- readBin(read.filename, integer(), n = 18)
# Print the data.
print(bindata)
# Read the values from 4th byte to 8th byte which represents "cyl".
cyldata = bindata[4:8]
print(cyldata)
# Read the values form 9th byte to 13th byte which represents "am".
amdata = bindata[9:13]
print(amdata)
# Read the values form 9th byte to 13th byte which represents "gear".
geardata = bindata[14:18]
print(geardata)
# Combine all the read values to a dat frame.
finaldata = cbind(cyldata, amdata, geardata)
colnames(finaldata) = column.names
print(finaldata)
When we execute the code above, it produces the following results and charts -
[1] 7108963 1728081249 7496037 6 6 4
[7] 6 8 1 1 1 0
[13] 0 4 4 4 3 3
[1] 6 6 4 6 8
[1] 1 1 1 0 0
[1] 4 4 4 3 3
cyl am gear
[1,] 6 1 4
[2,] 6 1 4
[3,] 4 1 4
[4,] 6 0 3
[5,] 8 0 3
As we can see, we get the raw data by reading the binary in R.