R语言 scan()用法及代码示例

R语言中的scan()函数用于扫描和读取数据。它通常用于在 R 语言中将数据读入向量或列表或文件中。

用法：
scan(“data.txt”, what = “character”)

参数：
数据.txt：要扫描的文本文件

返回：扫描输出

范例1：文本扫描


# R Program to scan a file
  
# Create example data.frame
data <- data.frame(x1 = c(1, 2, 2, 3),                
                   x2 = c(4, 5, 6, 7),
                   x3 = c(8, 9, 10, 11))
data  
  
# Write data as txt file to directory
write.table(data,                    
            file = "data.txt",
            row.names = FALSE)
  
# Get currently used directory
getwd()   
              
# Apply scan function to txt file
data <- scan("data.txt", what = "character")   
data

输出：

  x1 x2 x3
1  1  4  8
2  2  5  9
3  2  6 10
4  3  7 11

[1] "/home/cg/root/8121844"

[1] "x1" "x2" "x3" "1"  "4"  "8"  "2"  "5"  "9"  "2"  "6"  "10" "3"  "7"  "11"
Read 15 items

范例2：将数据扫描为文本


# R Program to scan a file
  
# Create example data.frame
data <- data.frame(x1 = c(1, 2, 2, 3),                
                   x2 = c(4, 5, 6, 7),
                   x3 = c(8, 9, 10, 11))
data  
  
# Write data as txt file to directory
write.table(data,                    
            file = "data.txt",
            row.names = FALSE)
          
# Read txt file into list
data <- scan("data.txt", what = list("", "", ""))    
data

输出：

  x1 x2 x3
1  1  4  8
2  2  5  9
3  2  6 10
4  3  7 11
[[1]]
[1] "x1" "1"  "2"  "2"  "3" 

[[2]]
[1] "x2" "4"  "5"  "6"  "7" 

[[3]]
[1] "x3" "8"  "9"  "10" "11"

Read 5 records

范例3：具有扫描函数的跳线


# R Program to scan a file
  
# Create example data.frame
data <- data.frame(x1 = c(1, 2, 2, 3),  
                   x2 = c(4, 5, 6, 7),
                   x3 = c(8, 9, 10, 11))
data  
  
# Write data as txt file to directory
write.table(data,
            file = "data.txt",
            row.names = FALSE)
              
# Skip first line of txt file
data <- scan("data.txt", skip = 1)                   
data

输出：

  x1 x2 x3
1  1  4  8
2  2  5  9
3  2  6 10
4  3  7 11
 [1]  1  4  8  2  5  9  2  6 10  3  7 11
Read 12 items

范例4：扫描 Excel CSV 文件


# R Program to scan a file
  
# Create example data.frame
data <- data.frame(x1 = c(1, 2, 2, 3), 
                   x2 = c(4, 5, 6, 7),
                   x3 = c(8, 9, 10, 11))
data  
  
# Write data as csv file to directory
write.table(data,                
            file = "data.csv",
            row.names = FALSE)
              
# Apply scan function to csv file           
data <- scan("data.csv", what = "character")        
data

输出：

  x1 x2 x3
  x1 x2 x3
1  1  4  8
2  2  5  9
3  2  6 10
4  3  7 11
Read 15 items
 [1] "x1" "x2" "x3" "1"  "4"  "8"  "2"  "5"  "9"  "2"  "6"  "10" "3"  "7"  "11"

范例5：从键盘读取输入。


# take input from keyboard
z <- scan() 
1
2
3
4
   
# print output on the screen
print(z)

输出：

Read 4 items
[1] 1 2 3 4

这里，在上面的代码中，scan() 函数将使用 print() 函数从用户那里获取输入并打印值。

相关用法

注：本文由纯净天空筛选整理自kaurbal1698大神的英文原创作品 Scan and Read Data from a File in R Programming – scan() Function。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。