Clojure sequence operation

Question

How to get a new sequence from an old sequence, the elements of the new one are from the old one until a condition is met

Suppose the condition is #(> % 0)

'(1 2 3 0 3 2 0 1) returns 1, 2, 3

'(0 1 2 3) returns empty seq

'(1 2 3) returns everything.

Note it's not same as filter.

mikera · Accepted Answer · 2012-03-23 06:00:19Z

6

You probably want to use take-while:

(take-while #(> % 0) '(1 2 3 0 3 2 0 1))
=> (1 2 3)

answered Mar 23, 2012 at 6:00

mikera

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1 Comment

Or even (take-while pos? '(1 2 3 0 3 2 0 1)), in this specific case.

sw1nn · Accepted Answer · 2012-03-23 09:16:10Z

3

mikera's answer looks good, but also consider split-with if you need to do further processing on the rest of the list.

=> (split-with #(> % 0) '(1 2 3 0 3 2 0 1))
[(1 2 3) (0 3 2 0 1)]

answered Mar 23, 2012 at 9:16

sw1nn

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jbear · Accepted Answer · 2012-03-25 04:01:49Z

2

This is the joy of Clojure: there are so many ways to skin a cat:

(for [i '(1 2 3 0 3 2 0 1) :while (> i 0)] i)
=> (1 2 3)

answered Mar 25, 2012 at 4:01

jbear

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