r - split column if variable number of pieces data.frame -

i want split column y of df below according '_' data incomplet. (df representative portion of bigger data.frame).

df <- data.frame(x = 1:10,                  y = c("vuh_ftu_yefq", "sos_nvtspb", "pfymm_ucms",                        "tucbexcqzh", "n_zndbhoun", "wdetzaolvn",                        "lvohrpdqns", "wso_bsqwvr", "wx_gbkbxjl",                        "t_dbxkkvge")) 

i have tried using:

df$z <- strsplit(df$y,'_') 

but error because number of pieces in each list different.

how can this?

assumptions:

• ) needed close out df in example.
• incomplete data means it's filled in left such value without intervening '_' first or datum.

tidyr's separate():

result <- separate(df, y, = c("z1","z2","z3") , sep ='_', = "drop") 

• the key here extra = "drop" according docs always returns length(into) pieces dropping or expanding necessary.

data.table's tstrsplit()

dt <- as.data.table(df) result <- dt[, c("z1", "z2","z3") := tstrsplit(y, '_', fixed=true)][] 

• the default behaviour tstrsplit() need , fixed=true pass strsplit() underneath keep things hasty.

note: if incomplete data filled right need unmix variables here!!!