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Operation between two vectors. op is one of the operators below :

The vectors returned by these boolean operators are boolean vectors (containing only 1 where result is true, 0 where it is false) :

In all of the above operations, a missing value in one of the input vectors results in a corresponding missing value in the output vector.

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# copies fields 1, 5, 9, 13, 17 of x into y
Y = X[1,20,4]

vector vector[vector]

Extract a selection of elements from a vector. The vector supplied as the argument provides the set of indices to be used. For example:

v = |10, 20, 30, 40|
i = |2, 1, 3|
r = v[i] # r is now |20, 10, 30|   

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Takes two vectors, and returns a new vector containing only the values of the first vector where the second vector's values are non-zero and non-missing. Examples:

v1 = filter(v, v>273.15) # returns only the values above 273.15
v2 = filter(v, v <> vector_missing_value) # returns only the non-missing values

Searches the given vector for a number and returns the index of the first occurrence of it. If an optional third argument is given as the string 'all', then a vector of the indexes of all occurrences of the number is returned. In both cases, if the number is not contained in the vector, nil is returned.

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