[R] replace "" to NA.

[vikram ranga]

Dear All,

I am bit stuck to a problem of replacing "" to NA.
I have big data set but here is the toy example:-

test<-data.frame(
test1=c("","Hi","Hello"),
test2=c("Hi","","Bye"),
test3=c("Hello","",""))

If the data as in above, I could change all "" to NA by this code:-

for(i in 1:3){
for(j in 1:3){
if(test[j,i]==""){
test[j,i]=NA
}
}
}

but the problem arises if data frame has NA at some places

test<-data.frame(
test1=c("","Hi","Hello"),
test2=c("Hi",NA,"Bye"),
test3=c("Hello","",""))

the above loop script does not work on this data frame as NA is has
logical class and does not return TRUE/FALSE.

Can anyone provide some help?

My sessionInfo is:
R version 3.0.2 (2013-09-25)
Platform: i386-w64-mingw32/i386 (32-bit)

locale:
[1] LC_COLLATE=English_India.1252  LC_CTYPE=English_India.1252
LC_MONETARY=English_India.1252
[4] LC_NUMERIC=C                   LC_TIME=English_India.1252

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
 [1] RColorBrewer_1.0-5 plotrix_3.5-2      foreign_0.8-57
splancs_2.01-34    spatstat_1.34-0
 [6] polyclip_1.1-0     tensor_1.5         abind_1.4-0
deldir_0.1-1       mgcv_1.7-26
[11] nlme_3.1-111       xlsx_0.5.1         xlsxjars_0.5.0
rJava_0.9-4        ggplot2_0.9.3.1
[16] rgdal_0.8-11       rgeos_0.3-2        maptools_0.8-27    sp_1.0-14

loaded via a namespace (and not attached):
 [1] colorspace_1.2-4 dichromat_2.0-0  digest_0.6.3     grid_3.0.2
  gtable_0.1.2
 [6] labeling_0.2     lattice_0.20-23  MASS_7.3-29      Matrix_1.0-14
  munsell_0.4.2
[11] plyr_1.8         proto_0.3-10     reshape2_1.2.2   scales_0.2.3
  stringr_0.6.2
[16] tcltk_3.0.2      tools_3.0.2