你可以使用R中的以下方法从十六进制中获取32位小端值：

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英文:

How can I get the 32-bit little-endian value from hex in R?

问题

I have a data file with the following hex values in bytes 17:20
> 92 02 00 00

According to https://hexed.it/, the 32-bit integer of these bytes (signed or unsigned) is 658. How can I get the value 658 from these raw values? Note that this is Little-endian ordered.

  1. > readBin(img_path, "raw", 20)[17:20]
  2. [1] 92 02 00 00

你可以使用R中的以下方法从十六进制中获取32位小端值：

根据 https://hexed.it/ 的信息，这些字节的32位整数（有符号或无符号）是658。如何从这些原始值中获取值658？请注意这是小端序排列。

  1. > readBin(img_path, "raw", 20)[17:20]
  2. [1] 92 02 00 00

你可以使用R中的以下方法从十六进制中获取32位小端值：

英文:

I have a data file with the following hex values in bytes 17:20
> 92 02 00 00

According to https://hexed.it/, the 32-bit integer of these bytes (signed or unsigned) is 658. How can I get the value 658 from these raw values? Note that this is Little-endian ordered.

  1. > readBin(img_path, "raw", 20)[17:20]
  2. [1] 92 02 00 00

你可以使用R中的以下方法从十六进制中获取32位小端值：

答案1

得分: 1

如果你将文件作为字符读取，你可以使用 strtoi 函数。

  1. hex_to_int = function(x) {
  2.   i = 256^(0:(length(x)-1)) * strtoi(x, base = 16L)
  3.   sum(i)
  4. }
  6. x  = c("92", "02", "00", "00")
  7. hex_to_int(x)
  8. # [1] 658

希望这对你有所帮助。

英文:

If you read from the file as character, you can use strtoi

  1. hex_to_int = function(x) {
  2.   i = 256^(0:(length(x)-1)) * strtoi(x, base = 16L)
  3.   sum(i)
  4. }
  6. x  = c("92", "02", "00", "00")
  7. hex_to_int(x)
  8. # [1] 658

答案2

得分: 1

如果您有一个原始向量，您可以使用readBin函数将其转换为整数。例如：

  1. x <- as.raw(c(146, 2, 0, 0))
  2. x
  3. # [1] 92 02 00 00
  4. readBin(x, integer(), n=1, size=4, endian = "little")
  5. # [1] 658

请注意，以上是代码示例，用于将原始向量转换为整数。

英文:

If you have a raw vector you can use readBin to convert to integer. For example

  1. x &lt;- as.raw(c(146, 2, 0, 0))
  2. x
  3. # [1] 92 02 00 00
  4. readBin(x, integer(), n=1, size=4, endian = &quot;little&quot;)
  5. # [1] 658

答案3

得分: 0

以下是代码的翻译部分：

  1. # 一种手动执行的方法是：
  2. get_32bit_unsigned <- function(raw_32bit) {
  3.   if (!(inherits(raw_32bit, 'raw') & length(raw_32bit) == 4)) {
  4.     rlang::abort('raw_32bit必须是一个32位原始向量')
  5.   }
  6.   width_in_bits = rawToBits(raw_32bit)
  7.   v = 0
  8.   for (i in 1:length(width_in_bits)) {
  9.     v = v + 2^(i-1) * as.integer(width_in_bits[i])
  10.   }
  11.   return(v)
  12. }
  14. get_32bit_unsigned(readBin(img_path, "raw", 20)[17:20])
  15. # 输出：658

希望这对你有所帮助。如果你需要进一步的帮助，请随时提问。

英文:

One way to do this is manually:

  1. get_32bit_unsigned &lt;- function(raw_32bit) {
  2.   if(!( inherits(raw_32bit, &#39;raw&#39;) &amp; length(raw_32bit) == 4)) {
  3.     rlang::abort(&#39;raw_32bit must be a 32-bit raw vector&#39;)
  4.   }
  5.   width_in_bits = rawToBits(raw_32bit)
  6.   v = 0
  7.   for(i in 1:length(width_in_bits)) {
  8.     v = v + 2^(i-1)*as.integer(width_in_bits[i])
  9.   }
  10.   return(v)
  11. }
  13. get_32bit_unsigned(readBin(img_path, &quot;raw&quot;, 20)[17:20])
  14. &gt; 658

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  • 本文由 发表于 2023年3月4日 05:24:25
  • 转载请务必保留本文链接：https://go.coder-hub.com/75632002.html
  • binaryfiles
  • hex
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