[R] RE : avoiding a loop: "cumsum-like"

Tue Nov 7 17:02:26 CET 2006

Thanks Petr for taking a stab at it.
I have yet to figure out a way to do it, but if I do I'll post it.
Cheers

David

-----Message d'origine-----
De : Petr Pikal [mailto:petr.pikal at precheza.cz] 
Envoyé : vendredi 3 novembre 2006 09:05
À : GOUACHE David; r-help at stat.math.ethz.ch
Objet : Re: [R] avoiding a loop: "cumsum-like"

Hi

I have not seen any answer yet so I wil try (partly).

I believe that the loop can be vectorised but I am a little bit lost 
in your fors and ifs. I found that first part of res is same as 
cumsum(tab$x.jour) until about 81st value. However I did not decipher 
how to compute the remaining part. I tried to add 
cumsum(tab$posit.lat) (after changing NA to 0) what is not correct.

Probably some combination of logical operation and summing can do 
what you want. I thought that something like
((cumsum(tab$posit.lat)*0.8)*(cumsum(tab$x.jour)>30)+cumsum(tab$x.jour
))

can do it but the result is defferent from your computation.
Not much of help, but maybe you can do better with above suggestion.

Petr

On 2 Nov 2006 at 11:15, GOUACHE David wrote:

Date sent:      	Thu, 2 Nov 2006 11:15:49 +0100
From:           	"GOUACHE David" <D.GOUACHE at arvalisinstitutduvegetal.fr>
To:             	<r-help at stat.math.ethz.ch>
Subject:        	[R] avoiding a loop: "cumsum-like"

> Hello Rhelpers,
> 
> I need to run the following loop over a large number of data-sets, and
> was wondering if it could somehow be vectorized. It's more or less a
> cumulative sum, but slightly more complex. Here's the code, and an
> example dataset (called tab in my code) follows. Thanks in advance for
> any suggestions!
> 
> res<-0
> for (i in min(tab$Date):max(tab$Date))
> {
>  if (is.na(tab$posit.lat[tab$Date==i])==T)
>  {
>   res<-c(res,res[length(res)]+tab$x.jour[tab$Date==i])
>  }
>  else
>  {
>   if (res[tab$posit.lat[tab$Date==i]+1]<30)
>   {
>    res<-c(res,res[length(res)]+tab$x.jour[tab$Date==i])
>   }
>   else
>   {
>    res<-c(res,res[length(res)]+tab$x.jour[tab$Date==i]+0.8*res[tab$pos
>    it.lat[tab$Date==i]+1])
>   }
>  }
> }
> res[-1]
> 
> 
> Date	x.jour	posit.lat
> 35804	0	NA
> 35805	0	NA
> 35806	0	NA
> 35807	0	NA
> 35808	0	NA
> 35809	2.97338883	NA
> 35810	2.796389915	NA
> 35811	0	NA
> 35812	0	NA
> 35813	1.000711886	NA
> 35814	0.894422571	NA
> 35815	0	NA
> 35816	0	NA
> 35817	0	NA
> 35818	0	NA
> 35819	0	NA
> 35820	0	NA
> 35821	0	NA
> 35822	0	NA
> 35823	0	NA
> 35824	0	NA
> 35825	0	NA
> 35826	0	NA
> 35827	0	NA
> 35828	0	NA
> 35829	0	NA
> 35830	0	NA
> 35831	0	NA
> 35832	0	NA
> 35833	0	NA
> 35834	0	NA
> 35835	0	NA
> 35836	0	NA
> 35837	0	NA
> 35838	0	NA
> 35839	0	NA
> 35840	2.47237455	NA
> 35841	0	2
> 35842	0	3
> 35843	0	4
> 35844	0	5
> 35845	0	6
> 35846	0	7
> 35847	4.842160488	8
> 35848	2.432125036	9
> 35849	0	10
> 35850	0	12
> 35851	0	14
> 35852	0	16
> 35853	3.739683882	18
> 35854	1.980214421	20
> 35855	0	22
> 35856	0	24
> 35857	5.953444078	27
> 35858	6.455722475	29
> 35859	0	31
> 35860	3.798690334	32
> 35861	6.222993364	34
> 35862	3.746243098	35
> 35863	0	35
> 35864	0	36
> 35865	0	37
> 35866	0	38
> 35867	0	38
> 35868	0	39
> 35869	0	40
> 35870	0	41
> 35871	0	42
> 35872	0	43
> 35873	0	44
> 35874	0	45
> 35875	0	46
> 35876	0	47
> 35877	1.951774892	48
> 35878	0	49
> 35879	0	50
> 35880	1.702837643	50
> 35881	0	52
> 35882	0	53
> 35883	0	54
> 35884	0	55
> 35885	5.953444078	57
> 35886	0	58
> 35887	5.737515358	59
> 35888	0	61
> 35889	6.215941227	63
> 35890	4.731576675	64
> 35891	0	66
> 35892	2.255448314	66
> 35893	3.782283008	67
> 35894	3.244474546	68
> 35895	1.808553193	69
> 35896	2.622680002	70
> 35897	0	71
> 35898	0	72
> 35899	0	72
> 35900	1.7084177	73
> 35901	1.28455982	74
> 35902	2.320013736	76
> 35903	0	77
> 35904	0	78
> 35905	0	79
> 35906	0	79
> 35907	0	80
> 35908	6.716812458	81
> 35909	0	82
> 35910	6.796571531	84
> 35911	5.573668337	85
> 35912	5.42513958	86
> 35913	3.774513877	86
> 35914	0	87
> 35915	0	89
> 35916	0	90
> 35917	4.208252725	91
> 35918	0	92
> 35919	0	93
> 35920	0	95
> 35921	5.70023661	97
> 35922	0	98
> 35923	0	100
> 35924	0	102
> 35925	0	103
> 35926	0	104
> 
> David Gouache
> Arvalis - Institut du Végétal
> Station de La Miničre
> 78280 Guyancourt
> Tel: 01.30.12.96.22 / Port: 06.86.08.94.32
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html and provide commented,
> minimal, self-contained, reproducible code.

Petr Pikal
petr.pikal at precheza.cz

David Gouache
Arvalis - Institut du Végétal
Station de La Minière
78280 Guyancourt
Tel: 01.30.12.96.22 / Port: 06.86.08.94.32