dataframe - R how to retrieve data from data.frame with multiple conditions -


i wondering how perform basic data manipulation in r. want following.

i have data table following pattern : 

  v1     v2     v3       abc     x     24   abc     y     30   efg     x     4   efg     y     28   hij     p     40   hij     y     41   pkl     x     32

  1. now want retrieve values/pairs of v1 doesn't have corresponding value not x on v2. in above dataset subset 

    hij     p    40 hij     y    41

since neither of pair of hij have v2 value of x.

  1. i retrieve values of v1 don't repeat twice. in above example 

    pkl  x 32

you mentioned data.table, here's 2 possible approaches both requests

library(data.table)

for 1.

setdt(df)[, .sd[all(v2 != "x")], = v1] #     v1 v2 v3 # 1: hij  p 40 # 2: hij  y 41

for 2.

df[, .sd[.n == 1l], = v1] #     v1 v2 v3 # 1: pkl  x 32

or (a bit more optimized version)

indx <- df[, .(indx = .i[.n == 1l]), = v1]$indx df[indx] #     v1 v2 v3 # 1: pkl  x 32

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