Javascript 从多行字符串中删除前导和尾随空格，并用逗号替换其余的空格块

Question

How can I convert this text

data=`ID   ra      dec     V       VR      MJD
  100     30.1  +15     7.00    -10     2450000.1234
200   30.2      +16     12.226  -5.124  2450000.2345
   300  30.3     +17    13.022  12.777    2450000.3456


400      30.4  +18     14.880  13.666  2450000.6789
500 30.5        +19 12.892      -1.835  2450001
 600     30.6    +20     17.587  15.340  2450002.123
700     30.7    +21       13.984  13.903  2450000.123456 
800    30.8    +22     20.00   10.000  2450003.0     `

ie an imported text with multiple lines and columns separated by spaces and tabs, into this

ID,ra,dec,V,VR,MJD
100,30.1,+15,7.00,-10,2450000.1234
200,30.2,+16,12.226,-5.124,2450000.2345
300,30.3,+17,13.022,12.777,2450000.3456


400,30.4,+18,14.880,13.666,2450000.6789
500,30.5,+19,12.892,-1.835,2450001
600,30.6,+20,17.587,15.340,2450002.123
700,30.7,+21,13.984,13.903,2450000.123456
800,30.8,+22,20.00,10.000,2450003.0

Unfortunately,

• this regex data=data.replace(/^\s+|\s+$/g,'').replace(/[\t \r]+/g,','); only works with the first line,
• this one data.replace(/[^\S\r\n]+$/gm, "").replace(/[\t \r]+/g,','); is ok, but only for for for traling.

Extra: How can I transform it to a json which separate the two blocks into two datasets such as [[{id:..., ra:...},{},{}],[{id:..., ra:...},{},{}]]

Answer 1

The string conversion might be easier with split/join and trim:

data
    .split(/\r?\n/)
    .map(row => row.trim().split(/\s+/).join(','))
    .join('\n')

The extra credit is a little more involved. :)

const rows = data.split(/\r?\n/).map(row => row.trim().split(/\s+/).join(','));
const keys = rows.shift().split(',');
const chunks = rows.join("\n").split(/\n{2,}/);

const output = chunks .map(chunk => chunk.split("\n").map(
    row => row.split(',').reduce((obj, v, i) => {
        obj[keys[i]] = v;
        return obj;
    }, {})
));

Answer 2

You're nearly there. You want the multiline flag on the first replace, but don't replace \n , so don't use \s . Use [ \t] instead:

 var data = 'ID ra dec V VR MJD\n' + ' 100 30.1 +15 7.00 -10 2450000.1234\n' + '200 30.2 +16 12.226 -5.124 2450000.2345\n' + ' 300 30.3 +17 13.022 12.777 2450000.3456\n' + '\n' + '\n' + '400 30.4 +18 14.880 13.666 2450000.6789\n' + '500 30.5 +19 12.892 -1.835 2450001\n' + ' 600 30.6 +20 17.587 15.340 2450002.123\n' + '700 30.7 +21 13.984 13.903 2450000.123456\n' + '800 30.8 +22 20.00 10.000 2450003.0 \n' var result = data.replace(/^[ \t]+|[ \t]+$/gm,'').replace(/[ \t]+/g,',') console.log(result);

Answer 3

 // First: the trimming part. Split on newlines, process // each line by trimming it and replacing remaining white // space with commas var data = 'ID ra dec V VR MJD\n\ 100 30.1 +15 7.00 -10 2450000.1234\n\ 200 30.2 +16 12.226 -5.124 2450000.2345\n\ 300 30.3 +17 13.022 12.777 2450000.3456\n\ \n\ \n\ 400 30.4 +18 14.880 13.666 2450000.6789\n\ 500 30.5 +19 12.892 -1.835 2450001\n\ 600 30.6 +20 17.587 15.340 2450002.123\n\ 700 30.7 +21 13.984 13.903 2450000.123456 \n\ 800 30.8 +22 20.00 10.000 2450003.0 '; data = data.split('\n'); var i = 0, l = data.length; for ( ; i < l; i++) data[i] = data[i].trim().replace(/\s+/g,','); data = data.join('\n'); document.write('<h1>Formatted data string</h1><pre><code>'+data+'</code></pre>'); // Now to turn it into objects. // We'll strip the first line because // that'll be the list of column names: var cols = data.replace(/^([^\n]+)\n/,'$1').split(','), columnCount = cols.length; data = data.replace(/^[^\n]+\n/,''); // Now separate the 2 datasets var datasets = data.split('\n\n\n'); document.write('<h1>First dataset</h1><pre><code>'+datasets[0]+'</code></pre>'); document.write('<h1>Second dataset</h1><pre><code>'+datasets[1]+'</code></pre>') // Now we go through each line and // place the values into objects which // we'll push to an array var processed = []; i = 0; l = datasets.length; for ( ; i < l; i++){ processed[i] = []; var lines = datasets[i].split('\n'), lineCount = lines.length; for (var j = 0; j < lineCount; j++){ var dataArray = lines [j].split(','), obj = {}; for (var k = 0; k < columnCount; k++) obj[cols[k]] = dataArray[k]; processed[i].push(obj); } } var finalJSON = JSON.stringify(processed); document.write('<h1>Final JSON</h1><pre><code>'+finalJSON+'</code></pre>');

Answer 4

So, since you know the exact format of each line, you can use capture groups on a per-line basis to extract the details. Try something like this:

/^\s*(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s*$/mg

Remember that \s matches all whitespace, while \S matches non-whitespace. You may need to tweak the capture groups to your liking, if necessary. Then, using the multiline and global flags, we are all set up to iterate over all the matches.

Here's the code:

// Your data, with the header removed, formatted as a string literal:
var data = "100     30.1  +15     7.00    -10     2450000.1234\n"+
"200   30.2      +16     12.226  -5.124  2450000.2345\n"+
"   300  30.3     +17    13.022  12.777    2450000.3456\n"+
"\n"+
"\n"+
"400      30.4  +18     14.880  13.666  2450000.6789\n"+
"500 30.5        +19 12.892      -1.835  2450001\n"+
" 600     30.6    +20     17.587  15.340  2450002.123\n"+
"700     30.7    +21       13.984  13.903  2450000.123456 \n"+
"800    30.8    +22     20.00   10.000  2450003.0";

// The pattern to grab the data:
var data_pattern = /^\s*(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s+(\S+)\s*$/mg;

// Keep matching until we run out of lines that match...
var results = [];
var line_match;
while ((line_match = data_pattern.exec(data)) !== null){
    // Parse the match into a json object and add it to the results.
    results.push({
        ID: line_match[1],
        ra: line_match[2],
        dec: line_match[3],
        V: line_match[4],
        VR: line_match[5],
        MJD: line_match[6]
    });
}

// Output the results.
console.log(JSON.stringify(results, null, 2));

And here's the results on the console:

[
  {
    "ID": "100",
    "ra": "30.1",
    "dec": "+15",
    "V": "7.00",
    "VR": "-10",
    "MJD": "2450000.1234"
  },
  {
    "ID": "200",
    "ra": "30.2",
    "dec": "+16",
    "V": "12.226",
    "VR": "-5.124",
    "MJD": "2450000.2345"
  },
  {
    "ID": "300",
    "ra": "30.3",
    "dec": "+17",
    "V": "13.022",
    "VR": "12.777",
    "MJD": "2450000.3456"
  },
  {
    "ID": "400",
    "ra": "30.4",
    "dec": "+18",
    "V": "14.880",
    "VR": "13.666",
    "MJD": "2450000.6789"
  },
  {
    "ID": "500",
    "ra": "30.5",
    "dec": "+19",
    "V": "12.892",
    "VR": "-1.835",
    "MJD": "2450001"
  },
  {
    "ID": "600",
    "ra": "30.6",
    "dec": "+20",
    "V": "17.587",
    "VR": "15.340",
    "MJD": "2450002.123"
  },
  {
    "ID": "700",
    "ra": "30.7",
    "dec": "+21",
    "V": "13.984",
    "VR": "13.903",
    "MJD": "2450000.123456"
  },
  {
    "ID": "800",
    "ra": "30.8",
    "dec": "+22",
    "V": "20.00",
    "VR": "10.000",
    "MJD": "2450003.0"
  }
]

I hope this helped.