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. Author manuscript; available in PMC: 2016 Mar 11.
Published in final edited form as: Proc ACM Int Conf Inf Knowl Manag. 2015 Oct;2015:1001–1010. doi: 10.1145/2806416.2806441

Algorithm 1 Distance-based Sampling with Fixed Threshold Algorithm (DSFT)

Input: D = {Di|1 ≤ i ≤ N, i ∈ Z}, T, C and ε.
Output: D̃ = {D̃i|1 ≤ i ≤ N, i ∈ Z}
1: Set ε1 = kε, ε2 = ε − ε1, k is computed due to theorem 5.4;
2: Set T∼=T+Lap(2Δε1), Δ is computed due to lemma 4.1;
3: For D1, release a DP dataset D̃1 with ε2C privacy budget;
4: Set count = 1, and j = 1;
5: for each time point ti with i ≥ 2 do
6:  if count ≥ C, then set D̃i = D̃j continue;
7:  Set d∼(Di,D∼j)=d(Di,D∼j)+Lap(2CΔε1)
8:  if d̃(Di, D̃j) ≥ T̃, then release D̃i at ti with ε2C budget, and set count = count + 1, and j = i;
9:  else use D̃j as the release of Di;
10:  if i == N and count < C, then release D̃N with all remaining privacy budget;
11: end for