How to join multiple arrays of strings List<string[]> into one string[]

Question

I have this list

    // sample data
    List<string[]> ListOfArrays = new List<string[]> { new string[]{ "key1", "key2", "key3" }, 
                                                       new string[]{ "value1", "value2", "value3" },
                                                       new string[]{ "item1", "item2", "item3" , "item4"} };

i want to join all paralleled indexes in the array with comma delimited string, this will result in converting List<string[]> to string[]

The expected result

     // expected result
     string[] joinedList = new string[] { "key1, value1, item1", 
                                          "key2, value2, item2", 
                                          "key3, value3, item3",
                                          "item4"};

is there a simple way to do this ? something like

string[] string.JoinMultiple(string delimiter, List<string[]>);

in the above case could be used like

string[] joinedList = string.JoinMultiple(",", ListOfArrays);

i've been searching a lot to find a solution for this but with no hope.

@NathanCooper what you are saying is actually very wrong just because i have 46 rep does not mean you should downvote ! i read how to ask carefully i demonstrated the problem very clearly the second code shows you the expected result ! read the question clearly before downvoting — someone
– someone, Commented Mar 15, 2015 at 23:33

Jacob Seleznev · Accepted Answer · 2015-03-15 23:24:50Z

2

You can try this:

        string[] joinedList = listOfArrays.SelectMany(
            strings => strings.Select((s, i) => new {s, i}))
            .ToLookup(arg => arg.i, arg => arg.s)
            .Select(grouping => string.Join(",", grouping)).ToArray();

or extension method:

    string[] joinedList = listOfArrays.JoinMultiple(",");
    ...
    public static string[] JoinMultiple(this List<string[]> lists,string delimiter)
    {
        return lists.SelectMany(
            strings => strings.Select((s, i) => new {s, i}))
            .ToLookup(arg => arg.i, arg => arg.s)
            .Select(grouping => string.Join(delimiter, grouping)).ToArray();
    }

edited Mar 15, 2015 at 23:24

answered Mar 15, 2015 at 23:16

Jacob Seleznev

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1 Comment

Jacob Seleznev Over a year ago

Fixed extension method. Thank you.

Jonathan Wood · Accepted Answer · 2015-03-15 23:22:32Z

0

I just put this method together. It produces the results you described.

public static string[] JoinMultiple(string delimiter, List<string[]> lists)
{
    int maxListLength = lists.Max(l => l.Count());
    string[] result = new string[maxListLength];
    for (int i = 0; i < maxListLength; i++)
    {
        result[i] = String.Join(delimiter,
            lists.Select(l => (i < l.Count()) ? l[i] : null)
                 .Where(s => s != null));
    }
    return result;
}

edited Mar 15, 2015 at 23:22

answered Mar 15, 2015 at 23:17

Jonathan Wood

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