在 R 编程中使用二进制文件

在计算机科学世界中，文本文件包含人类易于理解的数据。它包括字母、数字和其他字符。另一方面，二进制文件包含只有计算机才能解释的 1 和 0。存储在二进制文件中的信息无法被人类读取，因为其中的字节转换为包含各种其他不可打印字符的字符和符号。
当其他程序生成的数据对于 R 语言作为二进制文件处理必不可少时，有时可能会发生这种情况。此外，R 必须负责创建可以与其他程序共享的二进制文件。可以在二进制文件中执行的四个最重要的操作是：

• 创建和写入二进制文件
• 从二进制文件中读取
• 附加到二进制文件
• 删除二进制文件

创建和写入二进制文件

二进制文件的创建和写入都可以由单个函数writeBin()执行，方法是以“ wb ”模式打开文件，其中 w 表示写入，b 表示二进制模式。

Syntax: writeBin(object, con)
Parameters: 
object: an R object to be written to the connection 
con: a connection object or a character string naming a file or a raw vector. 
 

例子：

Python3

# R program to illustrate
# working with binary file
 
# Creating a data frame
df = data.frame(
  "ID" = c(1, 2, 3, 4),
  "Name" = c("Tony", "Thor", "Loki", "Hulk"),
  "Age" = c(20, 34, 24, 40),
  "Pin" = c(756083, 756001, 751003, 110011)
)
 
# Creating a connection object
# to write the binary file using mode "wb"
con = file("myfile.dat", "wb")
 
# Write the column names of the data frame
# to the connection object
writeBin(colnames(df), con)
 
# Write the records in each of the columns to the file
writeBin(c(df$ID, df$Name, df$Age, df$Pin), con)
 
# Close the connection object
close(con)

输出：

从二进制文件中读取

可以通过函数readBin()以“ rb ”模式打开文件来从二进制文件中读取，其中 r 表示读取，b 表示二进制模式。

Syntax: readBin(con, what, n )
Parameters: 
con: a connection object or a character string naming a file or a raw vector 
what: either an object whose mode will give the mode of the vector to be read or a character vector of length one describing the mode: one of “numeric”, “double”, “integer”, “int”, “logical”, “complex”, “character”, “raw” 
n: the (maximal) number of records to be read 
 

例子：

Python3

# R program to illustrate
# working with binary file
 
# Creating a connection object
# to read the file in binary mode using "rb".
con = file("myfile.dat", "rb")
 
# Read the column names
# n = 4 as here 4 column
colname = readBin(con, character(),  n = 4)
 
# Read column values
# n = 20 as here 16 values and 4 column names
con = file("myfile.dat", "rb")
bindata = readBin(con, integer(), n = 20)
 
# Read the ID values
# as first 1:4 byte for col name
# then values of ID col is within 5 to 8
ID = bindata[5:8]
 
# Similarly 9 to 12 byte for values of name column
Name = bindata[9:12]
 
# 13 to 16 byte for values of the age column
Age = bindata[13:16]
 
# 17 to 20 byte for values of Pincode column
PinCode = bindata[17:20]
 
# Combining all the values and make it a data frame
finaldata = cbind(ID, Name, Age, PinCode)
colnames(finaldata)= colname
print(finaldata)

输出：

ID       Name        Age        Pin
[1, ]          0          0          0          0
[2, ] 1072693248 1074266112 1074790400 1073741824
[3, ]          0          0          0          0
[4, ] 1073741824 1074790400 1074266112 1072693248

附加到二进制文件

附加到二进制文件可以由相同的函数writeBin()执行，方法是以“ ab ”模式打开文件，其中 a 表示附加，b 表示二进制模式。
例子：

Python3

# R program to illustrate
# working with binary file
 
# Creating another data frame
# to append with the existing data frame
df = data.frame(
  "Salary" = c(100, 200, 300, 400),
  "Experience" = c(3, 5, 10, 4)
)
 
# Creating a connection object
# to append the binary file using mode "ab"
con = file("myfile.dat", "ab")
 
# append the column names of the data frame
# to the connection object
writeBin(colnames(df), con)
 
# append the records in each of the columns to the file
writeBin(df$Salary, con)
 
# Close the connection object
close(con)

输出：

删除二进制文件

在 R 中，可以使用file.remove()命令删除二进制文件，然后使用unlink()函数取消链接已删除的文件。
例子：

Python3

# R program to illustrate
# working with binary file
 
# Define the file name that will be deleted
fileName <- "myfile.dat"
 
# Check its existence
if (file.exists(fileName))
  # Delete file if it exists
  file.remove(fileName)
 
# Unlink the deleted file
unlink(fileName, recursive = TRUE)