[R] Is it the PPS samples i needed in R?

[zhijie zhang]

Dear friends,
  I want to do a unequal probability sampling, that is, Probability
Proportionate to size, Is it right for the following programs?
Say my original dataset is:

 ID  Population
 1     100
 2     200
 3     300
 IF the population is large ,then the corresponding ID has the large
Probability to be selected.

sample(A$ID, size=2, replace = FALSE, prob = A$population)
#suppose the dataset name is A.
Is it the PPS samples  i needed ?
 Any suggestions are greatly welcome.

-- 
With Kind Regards,

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Zhi Jie,Zhang ,PHD
Tel:86-21-54237149   epistat at gmail.com
Dept. of Epidemiology,school of public health,Fudan University
Address:No. 138 Yi Xue Yuan Road,Shanghai,China
Postcode:200032
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