detecting measurement of specific id in column in R

Fri, Nov 23, 2018 2:55 AM

Dear all, dear Jim,

thanks so much for your efforts! The code seems to work well :)

All the best,

Vicci

Am Do., 22. Nov. 2018 um 23:34 Uhr schrieb Jim Lemon <drjimlemon at gmail.com>:

Hi Vicci,
It's very clunky, but I think it will do what you want.
rrdf<-read.csv(text="No,date,chamber,d13C,ppm_CO2,ppm_13CO2
 1,10.14.2018 10:43 PM,IN,-0.192,439.6908,4.9382
 2,10.14.2018 10:47 PM,101,-0.058,440.7646,4.9509
 3,10.14.2018 10:50 PM,103,-1.368,535.6602,5.9967
 4,10.14.2018 10:53 PM,104,-1.601,542.4841,6.0702
 5,10.14.2018 10:57 PM,105,-1.353,475.2809,5.3299
 6,10.14.2018 11:00 PM,106,-1.184,530.6732,5.9430
 7,10.14.2018 11:03 PM,107,-1.582,512.5939,5.7418
 8,10.14.2018 11:07 PM,108,-1.359,544.0658,6.0889
 9,10.14.2018 11:10 PM,109,-1.557,543.2651,6.0790
 10,10.14.2018 11:13 PM,110,-1.638,477.0006,5.3476
 11,10.14.2018 11:17 PM,111,-1.475,530.1569,5.9357
 12,10.14.2018 11:20 PM,IN,-0.039,439.3367,4.9350
 13,10.14.2018 11:23 PM,1,-0.061,439.7931,4.9400
 14,10.14.2018 11:26 PM,3,-0.510,456.0714,5.1201
 15,10.14.2018 11:30 PM,4,-0.510,456.5144,5.1250
 16,10.14.2018 11:33 PM,5,-0.767,454.4449,5.1005
 17,10.14.2018 11:37 PM,6,-0.788,459.7679,5.1600
 18,10.14.2018 11:40 PM,7,-0.978,456.6323,5.1240
 19,10.14.2018 11:43 PM,8,-0.742,450.4059,5.0556
 20,10.14.2018 11:47 PM,9,-0.675,451.6678,5.0700
 21,10.14.2018 11:50 PM,10,-0.880,455.5837,5.1127
 22,10.14.2018 11:53 PM,11,-0.912,463.0478,5.1960
 23,10.15.2018 12:01 AM,IN,-0.368,439.5525,4.9359
 24,10.15.2018 12:12 AM,102,-0.205,439.9343,4.9409
 25,10.15.2018 12:15 AM,112,-1.685,474.5002,5.3196
 26,10.15.2018 12:19 AM,113,-1.714,474.4248,5.3186
 27,10.15.2018 12:22 AM,114,-2.032,496.5623,5.5623
 28,10.15.2018 12:26 AM,115,-1.602,471.2034,5.2834
 29,10.15.2018 12:29 AM,116,-1.303,554.4268,6.2028
 30,10.15.2018 12:32 AM,117,-1.833,501.2357,5.6151
 31,10.15.2018 12:36 AM,118,-1.745,496.0126,5.5578
 32,10.15.2018 12:39 AM,119,-1.537,467.5305,5.2428
 33,10.15.2018 12:42 AM,120,-2.109,507.5778,5.6836",
 stringsAsFactors=FALSE)


rrdf$ppm_13CO2_delta<-rrdf$ppm_CO2_delta<-rrdf$d13C_delta<-NA
for(row in 1:nrow(rrdf)) {
 if(rrdf$chamber[row] == "IN")
  INval<-c(rrdf$d13C[row],rrdf$ppm_CO2[row],rrdf$ppm_13CO2[row])
 rrdf[row,c("d13C_delta","ppm_CO2_delta","ppm_13CO2_delta")]<-
  rrdf[row,c("d13C","ppm_CO2","ppm_13CO2")]-INval
}

Jim

On Fri, Nov 23, 2018 at 8:52 AM Romy Rehschuh via R-help
<r-help at r-project.org> wrote:

Dear all,

if the attachment didn?t arrive, maybe it works now.
I would like to substract the "IN" values (= the air which goes into the
chambers) for "d13C", "ppm_CO2" and "ppm_13CO2"
from the "d13C", "ppm_CO2" and "ppm_13CO2" for every single chamber.
I need to substract the "IN" values which were measured *before* the
chamber.

So the calculation would look like df$d13C [chambers] - df$d13C [IN]
                                                       df$ppm_CO2
[chambers] - df$ppm_13CO2 [IN]
                                                       df$ppm_13CO2
[chambers] - df$ ppm_13CO2 [IN]
--> for chamber 101-111 this should be the first "IN" (No 1)
--> for chamber 1-11 this should be the second "IN" (No 12)
...and so on

I tried sth. like which(abs(date-x) == min(abs(date-x), but it just gives
me the closest "IN" in time and not the "IN" before.

I would appreciate any help!
Thank you so much, Vicci

detecting measurement of specific id in column in R

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