Finds all positions of a pattern in a list.
Position[expr, pattern]
Position[expr, pattern, levelspec]
Position[expr, pattern, levelspec, n]
Position[pattern]
Position[{a, b, a, c, a}, a]
→ {{1}, {3}, {5}}Position[{1, 2, 3, 2, 1}, 2]
→ {{2}, {4}}Position[{1, 2, 3}, 4]
→ {}Position[{x, y, x, z}, x]
→ {{1}, {3}}Position[{a, b, a, c, a, b, a}, a, Infinity, 2]
→ {{1}, {3}}Position[{1, {2, 3}, {4, {5, 6}}}, _Integer, Infinity, 4]
→ {{1}, {2, 1}, {2, 2}, {3, 1}}