Building a Comma Separated List

Creating a comma separated list from IList string or IEnumerable string

.NET 4+

IList<string> strings = new List<string>{"1","2","testing"};
string joined = string.Join(",", strings);

Detail & Pre .Net 4.0 Solutions

IEnumerable<string> can be converted into a string array very easily with LINQ (.NET 3.5):

IEnumerable<string> strings = ...;
string[] array = strings.ToArray();

It's easy enough to write the equivalent helper method if you need to:

public static T[] ToArray(IEnumerable<T> source)
{
    return new List<T>(source).ToArray();
}

Then call it like this:

IEnumerable<string> strings = ...;
string[] array = Helpers.ToArray(strings);

You can then call string.Join. Of course, you don't have to use a helper method:

// C# 3 and .NET 3.5 way:
string joined = string.Join(",", strings.ToArray());
// C# 2 and .NET 2.0 way:
string joined = string.Join(",", new List<string>(strings).ToArray());

The latter is a bit of a mouthful though :)

This is likely to be the simplest way to do it, and quite performant as well - there are other questions about exactly what the performance is like, including (but not limited to) this one.

As of .NET 4.0, there are more overloads available in string.Join, so you can actually just write:

string joined = string.Join(",", strings);

Much simpler :)

Create a comma separated list from a column

The letters vector is in-built in R, and paste0 allows you to "collapse" vectors with specified separation characters, in this case a comma:

> paste0(letters[1:5], collapse=",")
[1] "a,b,c,d,e"

It wasn't clear what form these letters had in a dataframe, but if they were simply a column named, say letts, you could do this:

paste0( dfrm$letts, collapse=",")

shell: build a comma separated list ended with a period

echo -e "abc\ndef\nhij" | sed ':a;N;$!ba;s/\n/, /g'

explained here https://stackoverflow.com/a/1252191/2235381

How create a comma-separated string from items in a list

This is how I do it using join() in List:

main(List<String> arguments) {
  List cities = ['NY', 'LA', 'Tokyo'];

  String s = cities.join(', ');
  print(s);
}

How to create comma separated list of numbers based on numeric value in column

You can use df.apply to apply str.join on range object created from 'calc':

>>> df['my_comma_list'] = df.calc.apply(lambda x: ', '.join(map(str, range(1, x+1))))

  inventory_partner inventory_partner2  calc  my_comma_list
0                A1                 aa     1              1
1                A2                 bb     2           1, 2
2                A3                 cc     5  1, 2, 3, 4, 5
3                A4                 dd     4     1, 2, 3, 4
4                A5                 ee     5  1, 2, 3, 4, 5
5                A6                 ff     3        1, 2, 3

Create comma separated list from list of objects

I would avoid reflection if possible.

You can achieve it with compile time safety and readable code easily:

IEnumerable<string> personTexts = listOfPersons
    .Select(p => String.Join(",", p.ReferenceNumber, p.FirstName, p.Surname, ...));
string joined = String.Join(Environment.NewLine, personTexts);

You have full control over which property should be used and in which order.

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