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[Emacs-diffs] master c4a0eff 2/4: Add seq-partition and seq-group-by
From: |
Nicolas Petton |
Subject: |
[Emacs-diffs] master c4a0eff 2/4: Add seq-partition and seq-group-by |
Date: |
Fri, 06 Feb 2015 15:02:20 +0000 |
branch: master
commit c4a0eff0112298de0a97b63e4e22826bf2b4126c
Author: Nicolas Petton <address@hidden>
Commit: Nicolas Petton <address@hidden>
Add seq-partition and seq-group-by
* lisp/emacs-lisp/seq.el: Better docstring for seq.el functions
* test/automated/seq-tests.el: New tests for seq-partition and
seq-group-by
---
lisp/ChangeLog | 2 +-
lisp/emacs-lisp/seq.el | 27 +++++++++++++++++++++++++++
test/ChangeLog | 5 +++--
test/automated/seq-tests.el | 16 ++++++++++++++++
4 files changed, 47 insertions(+), 3 deletions(-)
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index aa58c53..0cd2a4d 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,6 +1,6 @@
2015-02-06 Nicolas Petton <address@hidden>
- * emacs-lisp/seq.el (seq-mapcat): New function.
+ * emacs-lisp/seq.el (seq-mapcat, seq-partition, seq-group-by): New
functions.
2015-02-06 Artur Malabarba <address@hidden>
diff --git a/lisp/emacs-lisp/seq.el b/lisp/emacs-lisp/seq.el
index bd234a3..cd45989 100644
--- a/lisp/emacs-lisp/seq.el
+++ b/lisp/emacs-lisp/seq.el
@@ -230,6 +230,33 @@ The result is a sequence of type TYPE, or a list if TYPE
is nil."
(apply #'seq-concatenate (or type 'list)
(seq-map function seq)))
+(defun seq-partition (seq n)
+ "Return a list of the elements of SEQ grouped into sub-sequences of length N.
+The last sequence may contain less than N elements. If N is a
+negative integer or 0, nil is returned."
+ (unless (< n 1)
+ (let ((result '()))
+ (while (not (seq-empty-p seq))
+ (push (seq-take seq n) result)
+ (setq seq (seq-drop seq n)))
+ (nreverse result))))
+
+(defun seq-group-by (function seq)
+ "Apply FUNCTION to each element of SEQ.
+Separate the elements of SEQ into an alist using the results as
+keys. Keys are compared using `equal'."
+ (nreverse
+ (seq-reduce
+ (lambda (acc elt)
+ (let* ((key (funcall function elt))
+ (cell (assoc key acc)))
+ (if cell
+ (setcdr cell (push elt (cdr cell)))
+ (push (list key elt) acc))
+ acc))
+ seq
+ nil)))
+
(defun seq--drop-list (list n)
"Optimized version of `seq-drop' for lists."
(while (and list (> n 0))
diff --git a/test/ChangeLog b/test/ChangeLog
index 9ae9db3..f9a54b5 100644
--- a/test/ChangeLog
+++ b/test/ChangeLog
@@ -1,6 +1,7 @@
-2015-02-02 Nicolas Petton <address@hidden>
+2015-02-06 Nicolas Petton <address@hidden>
- * automated/seq-tests.el: New test for seq-mapcat.
+ * automated/seq-tests.el: New tests for seq-mapcat, seq-partition
+ and seq-group-by.
2015-02-05 Artur Malabarba <address@hidden>
diff --git a/test/automated/seq-tests.el b/test/automated/seq-tests.el
index cc89c88..ecbc004 100644
--- a/test/automated/seq-tests.el
+++ b/test/automated/seq-tests.el
@@ -205,5 +205,21 @@ Evaluate BODY for each created sequence.
(should (equal (seq-mapcat #'seq-reverse '((3 2 1) (6 5 4)) 'vector)
'[1 2 3 4 5 6])))
+(ert-deftest test-seq-partition ()
+ (should (same-contents-p (seq-partition '(0 1 2 3 4 5 6 7) 3)
+ '((0 1 2) (3 4 5) (6 7))))
+ (should (same-contents-p (seq-partition '[0 1 2 3 4 5 6 7] 3)
+ '([0 1 2] [3 4 5] [6 7])))
+ (should (same-contents-p (seq-partition "Hello world" 2)
+ '("He" "ll" "o " "wo" "rl" "d")))
+ (should (equal (seq-partition '() 2) '()))
+ (should (equal (seq-partition '(1 2 3) -1) '())))
+
+(ert-deftest test-seq-group-by ()
+ (should (equal (seq-group-by #'test-sequences-oddp [1 2 3 4])
+ '((t 3 1) (nil 4 2))))
+ (should (equal (seq-group-by #'car '((a 1) (b 3) (c 4) (a 2)))
+ '((a (a 2) (a 1)) (b (b 3)) (c (c 4))))))
+
(provide 'seq-tests)
;;; seq-tests.el ends here