The evaluation metric for this competition is
[NDCG (Normalized discounted cumulative gain)](https://www.kaggle.com/wiki/NormalizedDiscountedCumulativeGain)
@k where k=5. NDCG is calculated as:
\[ DCG_k=\sum_{i=1}^k\frac{2^{rel_i}-1}{\log_2{\left(i+1\right)}}, \]
\[ nDCG_k=\frac{DCG_k}{IDCG_k}, \]
where \\(rel_i\\) is the relevance of the result at position \\(i\\).
\\(IDCG_k\\) is the maximum possible (ideal) \\(DCG\\) for a given set of queries. All NDCG calculations are relative values on the interval 0.0 to 1.0.
For each new user, you are to make a maximum of 5 predictions on the country of the first booking. The ground truth country is marked with relevance = 1, while the rest have relevance = 0.
For example, if for a particular user the destination is FR, then the predictions become:
[ FR ]  gives a \\(NDCG=\frac{2^{1}-1}{log_{2}(1+1)}=1.0\\)
[ US, FR ] gives a \\(DCG=\frac{2^{0}-1}{log_{2}(1+1)}+\frac{2^{1}-1}{log_{2}(2+1)}=\frac{1}{1.58496}=0.6309\\)
Submission File
For every user in the dataset, submission files should contain two columns: id and country.
The destination country predictions must be ordered such that the most probable destination country goes first.
The file should contain a header and have the following format:
id,country
000am9932b,NDF
000am9932b,US
000am9932b,IT
01wi37r0hw,FR
etc.