在Golang中解析格式化字符串

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英文:

Parse formatted string in Golang

问题

我正在尝试使用Golang解析GNSS RINEX文件。

例如,这是VERSION行的RINEX规范:

+--------------------+------------------------------------------+------------+
|RINEX VERSION / TYPE| - 格式版本 (2.11)                          | F9.2,11X,  |
|                    | - 文件类型 ('O' 表示观测数据)                |   A1,19X,  |
|                    | - 卫星系统: 空白或 'G': GPS                  |   A1,19X   |
|                    |                     'R': GLONASS            |            |
|                    |                     'S': Geostationary      |            |
|                    |                          signal payload     |            |
|                    |                     'E': Galileo            |            |
|                    |                     'M': Mixed              |            |
+--------------------+------------------------------------------+------------+

RINEX文件中的每一行都有固定的宽度为80个ASCII字符 + "\n"。在这个例子中,前9个字符表示版本号(浮点数)。

在Python中,我可以使用:

struct.unpack("9s11s1s19s1s19s20s", line)

这将返回一个包含7个字符串的元组。

我是Go的新手,一直在尝试使用fmt.Sscanf来读取格式化文本:

func main() {
    str := "     2.11           OBSERVATION DATA    G (GPS)             RINEX VERSION / TYPE\n"
    var value float32
    a, err := fmt.Sscanf(str,"%9.2f", &value)
    fmt.Println(a)
    fmt.Println(err)
    fmt.Println(value)
}

返回:

0
bad verb %. for float32
0

Go中是否有任何包允许解析固定宽度的数据?

如果没有,编写类似于Python的struct的东西可能是一个好方法吗?

英文:

I'm trying to parse a GNSS RINEX file using Golang.

For example, here's the RINEX specification for the VERSION line:

+--------------------+------------------------------------------+------------+
|RINEX VERSION / TYPE| - Format version (2.11)                  | F9.2,11X,  |
|                    | - File type ('O' for Observation Data)   |   A1,19X,  |
|                    | - Satellite System: blank or 'G': GPS    |   A1,19X   |
|                    |                     'R': GLONASS         |            |
|                    |                     'S': Geostationary   |            |
|                    |                          signal payload  |            |
|                    |                     'E': Galileo         |            |
|                    |                     'M': Mixed           |            |
+--------------------+------------------------------------------+------------+

Each line in a RINEX file has a fixed width of 80 ASCII characters + "\n". In this example the first 9 characters represent the version number (float).

In Python I might use:

struct.unpack("9s11s1s19s1s19s20s", line)

which would return a tuple with 7 strings.

I'm new to go and have been trying to use fmt.Sscanf for reading formatted text:

func main() {
    str := "     2.11           OBSERVATION DATA    G (GPS)             RINEX VERSION / TYPE\n"
    var value float32
    a, err := fmt.Sscanf(str,"%9.2f", &value)
    fmt.Println(a)
    fmt.Println(err)
    fmt.Println(value)
}

returns:

0
bad verb %. for float32
0

Is there any package in go that permits parsing of fixed width data?

And if not, what might be a good approach for writing something similar to Python's struct?

答案1

得分: 4

例如,

package main

import (
    "errors"
    "fmt"
    "strconv"
    "strings"
)

// http://gage14.upc.es/gLAB/HTML/LaunchHTML.html
// http://gage14.upc.es/gLAB/HTML/Observation_Rinex_v2.11.html

func parseVersionType(line string) (version float64, fileType, satellite, label string, err error) {
    label = line[60:80]
    if label != "RINEX VERSION / TYPE" {
        err = errors.New("未知的头标签")
        return
    }
    version, err = strconv.ParseFloat(strings.TrimSpace(line[0:9]), 64)
    if err != nil {
        return
    }
    fileType = line[20:21]
    satellite = line[40:41]
    return
}

func main() {
    line := "     2.11           OBSERVATION DATA    G (GPS)             RINEX VERSION / TYPE\n"
    version, fileType, satellite, label, err := parseVersionType(line)
    fmt.Printf("%g %q %q %q %v\n", version, fileType, satellite, label, err)
}

输出:

2.11 "O" "G" "RINEX VERSION / TYPE" <nil>
英文:

For example,

package main

import (
	&quot;errors&quot;
	&quot;fmt&quot;
	&quot;strconv&quot;
	&quot;strings&quot;
)

// http://gage14.upc.es/gLAB/HTML/LaunchHTML.html
// http://gage14.upc.es/gLAB/HTML/Observation_Rinex_v2.11.html

func parseVersionType(line string) (version float64, fileType, satellite, label string, err error) {
	label = line[60:80]
	if label != &quot;RINEX VERSION / TYPE&quot; {
		err = errors.New(&quot;Unknown header label&quot;)
		return
	}
	version, err = strconv.ParseFloat(strings.TrimSpace(line[0:9]), 64)
	if err != nil {
		return
	}
	fileType = line[20:21]
	satellite = line[40:41]
	return
}

func main() {
	line := &quot;     2.11           OBSERVATION DATA    G (GPS)             RINEX VERSION / TYPE\n&quot;
	version, fileType, satellite, label, err := parseVersionType(line)
	fmt.Printf(&quot;%g %q %q %q %v\n&quot;, version, fileType, satellite, label, err)
}

Output:

2.11 &quot;O&quot; &quot;G&quot; &quot;RINEX VERSION / TYPE&quot; &lt;nil&gt;

huangapple
  • 本文由 发表于 2014年8月1日 06:59:51
  • 转载请务必保留本文链接:https://go.coder-hub.com/25070312.html
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