CheckAscendingOrder

Please will someone improve this page remove /* */ around this request to show it.

This phrase can be used to check whether the items in a numeric vector are in ascending order

      </NV≥1⌽NV

The phrase may also be written in the following form, but it executes slower in some APL implementations:

      NV<.≥1⌽NV

Note that the test determines whether the items are in strictly ascending order - i.e. each item is larger than the last. If the vector contains duplicates it is not considered to be in ascending order.

To test whether a vector containing duplicates is in ascending order, you can use any of the following phrases. Performance characteristics vary depending on the length of NV and the APL interpreter used:

      </NV>1⌽NV
      NV<.>1⌽NV
      NV≡NV[⍋NV]
      (⍋NV)≡⍳⍴NV

In all cases, you should the check the result of the phrase when NV is an empty vector if this is important to your application.

Examples

      ⎕FX ⍕2 1⍴'r←CheckAscendingOrder NV' 'r←</NV≥1⌽NV'    
      CheckAscendingOrder 0 1 5 8 19 27
1
      CheckAscendingOrder ¯3.1 ¯3.0 1.5 5.3 17
1
      CheckAscendingOrder 1 3 2 5 7 8
0
      CheckAscendingOrder 1 2 3 5 7 8
1
      CheckAscendingOrder 1 1 2 5 7 8    ⍝ Contains duplicates
0

Compatibility

Checked with: APLX, APL+Win APL2, Dyalog, NARS2000 - Add as many as you can/like

Test Cases

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Test
 ⎕IO←0      ⍝ You may change this; however, zero IS the default in the Phrasebook
⍝⎕ML←3      ⍝ Enable this line in Dyalog APL if appropriate
 ⎕FX'r←CheckAscendingOrder NV' 'r←</NV≥1⌽NV'
⍝ ---- Start Test cases (do not delete this!)
NV←77.3 153.5 23.6 152.3 ¯19.3 24.5 61.1 40.1 ¯13.9 ¯46.6
0 ≡ CheckAscendingOrder NV
NV←NV[⍋NV]
1 ≡ CheckAscendingOrder NV
0 ≡ CheckAscendingOrder 1 1 1 2 2 2

Test my code, both Examples and Test Cases.

See also: ... {PhraseName} ---Add proper Wiki names. The pages do not necessarily must exist. If they don't they will show up on WantedPages and that's just fine

Mentor: SimonMarsden

Tags are used to create a list automatically - see ListAllTags Tags: <!Ascending> <Ordering> <Sorting> Use "!" to avoid unwanted links for CamelCase names

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