Extracting elements in a list based on conditions

Question

I have the list

\[ScriptCapitalD] = 
  {824, 1082, 1135, 1308, 1359, 1372, 1401, 1412, 1601, 
   1638, 1641, 1674, 1709, 1805, 1947, 2208}

I would like to extract a sublist according to certain defined conditions, such as extracting only values which lie in the range 1000-1500.

What is the best way to do this?

Select[\[ScriptCapitalD], 1000 <= # <= 1500 &] would do it. But there are many faster ways that already have answers somewhere here... — aardvark2012, Dec 02 '17 at 11:25

score 6 · Accepted Answer · edited Jun 16 '20 at 09:23

6

The standard Mathematica function for that kind of selection, is Select.

data = 
  {824, 1082, 1135, 1308, 1359, 1372, 1401, 1412, 1601, 1638, 1641, 1674, 1709, 
   1805, 1947, 2208};
Select[data, Between[#, {1000, 1500}] &]

{1082, 1135, 1308, 1359, 1372, 1401, 1412}

Update

Between has an operator form, so

Select[data, Between[{1000, 1500}]]

will work and is nicer.

Select has its operator form, too, so one can also write

Select[Between[{1000, 1500}]] @ data

edited Jun 16 '20 at 09:23

Community

1

answered Dec 02 '17 at 11:25

m_goldberg

107,779
16
103
257

Can you explain what the operator & does in the argument of Select? – Physkid Dec 02 '17 at 11:38
@Physkid When writing &, everything to the left of it becomes the body of a function. E.g with plus = # + #2 & then plus[2, 3] evaluates to 5 – Coolwater Dec 02 '17 at 11:43
@Physkid. Look up Function in the documentation. – m_goldberg Dec 02 '17 at 11:44
@m_goldberg I like your updated code-cleaner – Physkid Dec 03 '17 at 09:33

score 4 · Answer 2 · answered Dec 02 '17 at 11:27

4

sdt = Select[dt, 1000 <= # <= 1500 &]

{1082, 1135, 1308, 1359, 1372, 1401, 1412}

answered Dec 02 '17 at 11:27

Anxon Pués

907
5
13

score 1 · Answer 3 · answered Dec 02 '17 at 19:18

1

Cases[Clip[lst, {1000, 1500}, {0, 0}], Except[0]]

{1082, 1135, 1308, 1359, 1372, 1401, 1412}

Alternatives, based on Clip:

lst // Pick[#, Clip[#, {1000, 1500}, {0, 0}] // Unitize, 1] &
Clip[lst, {1000, 1500}, {0, 0}] /. 0 -> Nothing

answered Dec 02 '17 at 19:18

user1066

17,923
3
31
49

score 0 · Answer 4 · answered Dec 02 '17 at 15:54

0

If you selection criteria is always a window (Between[{a,b}]), sorting the data and then doing a binary search may be more efficient. See Windowed binary search

answered Dec 02 '17 at 15:54

John McGee

411
2
4

Extracting elements in a list based on conditions

4 Answers4

Update