Select
Sorry Jeff and David for not being clear! The total sample size should be at least 40, but the selection should be based on group ID. A different combination of Group ID could give at least 40. If I select group G1 with 25 count and G2 and with 15 counts then I can get a minimum of 40 counts. So G1 and G2 are selected. G1 25 G2 15 In another scenario, if G2, G3 and G4 are selected then the total count will be 58 which is greater than 40. So G2 , G3 and G4 could be selected. G2 15 G3 12 G4 31 So the restriction is to find group IDs that give a minim of 40. Once, I reached a minim of 40 then stop selecting group and output the data.. I am hope this helps
On Mon, Feb 11, 2019 at 5:09 PM Jeff Newmiller <jdnewmil at dcn.davis.ca.us> wrote:
This constraint was not clear in your original sample data set. Can you expand the data set to clarify how this requirement REALLY works? On February 11, 2019 3:00:15 PM PST, Val <valkremk at gmail.com> wrote:
Thank you David. However, this will not work for me. If the group ID selected then all of its observation should be included. On Mon, Feb 11, 2019 at 4:51 PM David L Carlson <dcarlson at tamu.edu> wrote:
First expand your data frame into a vector where G1 is repeated 25
times, G2 is repeated 15 times, etc. Then draw random samples of 40 from that vector:
grp <- rep(mydat$group, mydat$count) grp.sam <- sample(grp, 40) table(grp.sam)
grp.sam G1 G2 G3 G4 G5 10 9 5 13 3 ---------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77843-4352 -----Original Message----- From: R-help <r-help-bounces at r-project.org> On Behalf Of Val Sent: Monday, February 11, 2019 4:36 PM To: r-help at R-project.org (r-help at r-project.org)
<r-help at r-project.org>
Subject: [R] Select Hi all, I have a data frame with tow variables group and its size. mydat<- read.table( text='group count G1 25 G2 15 G3 12 G4 31 G5 10' , header = TRUE, as.is = TRUE ) I want to select group ID randomly (without replacement) until
the
sum of count reaches 40. So, in the first case, the data frame could be G4 31 65 10 In other case, it could be G5 10 G2 15 G3 12 How do I put sum of count variable is a minimum of 40 restriction? Than k you in advance I want to select group ids randomly until I reach the
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