Delete columns in text files with specific string

问题

I would like to delete collumns with a specific string "Gtype." from a .txt tab delimited file. I already have tried this command in R: df <- df[, -grep("GType.", colnames(df))] to do this task. However my matrix is too big (more than 13 GB), and R cannot deal with it. (Error: cannot allocate vector of size....)

My input file:

Log.NE122  Gtype.NE122  Log.NE144    Gtype.NE144
-0.33          AA          1.0           AB

My expected output:

   Log.NE122  Log.NE144  
    -0.33       1.0      

I am wondering that it works in bash. If someone have other options....

回答1:

Using awk:

awk 'NR==1{for (i=1; i<=NF; i++) if ($i ~ /Gtype/) a[i]; 
     else printf "%s%s", $i, OFS; print ""; next}
     {for (i=1; i<=NF; i++) if (!(i in a)) printf "%s%s", $i, OFS; print "" }' file
Log.NE122 Log.NE144
-0.33     1.0

回答2:

You can also try using the 'data.table' package and assign the columns NULL:

dt <- data.table(df)
dt[, colToDelete := NULL]

"data.table" tries to do most of its operations without having to make copies. The way that you are doing it on data.frames requires a copy to be made.

来源：https://stackoverflow.com/questions/23130502/delete-columns-in-text-files-with-specific-string