How to sort a List of Lists of integers?

Question

My structures are defined like this:

List<int> Column = new List<int>();
List<List<int>> Columns = new List<List<int>>();

I'm populating the structure like this:

Columns.Clear();
for (int x=0;...
{
    Column.Clear();
    Column.Add(0); // amount of adjustment for this list
    Column.Add(x);
    for (int y=0;...
        ...
        Column.Add(data);
        Column[0] += dataAdjustment; // keep running total of adjustment
    }
    Columns.Add(Column);
}

Then, I'm trying to get the data out like this:

Columns.Sort((r1, r2) => r1[0].CompareTo(r2[0]));
Column = Columns[0];

I only want the column with the least amount of adjustment.

My problem is that in the end, Column always has in it the last column added to the list of columns and not the column with the least amount of adjustment.

What am I doing wrong? How can I get the list with the least amount of adjustment running total?

Amit · Accepted Answer · 2015-11-26 22:20:14Z

6

What am I doing wrong?

You're reusing (and overwriting) the same Column for every iteration of your for loop. You need to allocate a new List<int>(); for each new column, so instead of:

for (int x=0;...
{
    Column.Clear();

Do:

for (int x=0;...
{
    List<int> Column = new List<int>();

answered Nov 26, 2015 at 22:20

Amit

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1 Comment

BoltBait Over a year ago

That did the trick. Thanks. I assumed that when I was done with the column (by adding it to the Columns list) that I could reuse it. I guess not.

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