Bioequivalence and Bioavailability Forum • loop ↔ vectorized ↔ direct

loop ↔ vectorized ↔ direct [Two-Stage / GS Designs]

posted by ElMaestro – Denmark, 2017-08-20 19:22 (2760 d 11:25 ago) – Posting: # 17726
Views: 29,302

Hi Hötzi,

❝ I don’t understand why you use vectors at all. What ’bout:

❝

df <- Nps*2-2

❝ if (!Is.St2) {


❝   q  <- qt(p=1-alpha1, df=df)
❝ } else {

❝   df <- df-1

❝   q  <- qt(p=1-alpha2, df=df)

❝ }

Simple, but I think I aready told you: qt is a computationally very expensive function. If we need "many" qt values then it makes much more sense in terms of computation to cache the well-defined ones.

Within the 1000000 iterations values from qt are needed many times, but each of them have defined ranges of DF's (up to the max number of subjects -3 [or 2 :-)

]) and alphas (two levels). Thus we make a cache of qt values prior to entering the iteration loop then we can just take a sample from the cache in stead of re-inventing the wheel for every call. Do the population of the arrays once, and rely on them during the iterations or whatever other functions that need them. The speedup can be massive both in R and in C.

—
Pass or fail!
ElMaestro

Complete thread:

Initial sample size guess for the Potvin methods ElMaestro 2017-08-19 15:04 [Two-Stage / GS Designs]
- Initial sample size guess for the Potvin methods Helmut 2017-08-19 16:06
  - Initial sample size guess for the Potvin methods ElMaestro 2017-08-19 16:14
    - Initial sample size guess for the Potvin methods Helmut 2017-08-19 17:12
      - Initial sample size guess for the Potvin methods ElMaestro 2017-08-19 17:17
        
        Confuse-a-Cat Helmut 2017-08-19 17:33
        
        Confuse-a-Cat ElMaestro 2017-08-19 17:56
    - loop ↔ vectorized ↔ direct Helmut 2017-08-20 14:40
      - loop ↔ vectorized ↔ direct ElMaestro 2017-08-20 15:22
        
        loop ↔ vectorized ↔ direct Helmut 2017-08-20 16:23
        
        loop ↔ vectorized ↔ directElMaestro 2017-08-20 17:22
- The n ext crackpot iteration ElMaestro 2017-08-19 20:04
  - The n ext crackpot iteration Helmut 2017-08-20 02:20
- The ultimate crackpot iteration! ElMaestro 2017-08-20 14:35
  - The ultimate crackpot iteration! Helmut 2017-08-20 15:11
    - The ultimate crackpot iteration! ElMaestro 2017-08-20 15:28
      - The ultimate crackpot iteration! Helmut 2017-08-20 16:06
        
        The ultimate crackpot iteration! ElMaestro 2017-08-20 16:15
        
        The ultimate crackpot iteration! Helmut 2017-08-20 18:58
        
        The ultimate crackpot iteration! ElMaestro 2017-08-20 19:32
        
        Suggested code ElMaestro 2017-08-21 18:13
        
        Nitpicker! Helmut 2017-08-22 13:33
        
        Nitpicker! ElMaestro 2017-08-22 17:27
        
        Nitpicker! Helmut 2017-08-22 17:49
        
        Nitpicker! ElMaestro 2017-08-22 17:59
        
        Nitpicker! Helmut 2017-08-22 19:15
        
        Benchmark code ElMaestro 2017-08-22 22:29
        
        Benchmark code Helmut 2017-08-23 01:48