In post #1, the labels in your sample input files were "train statistics" and "test statistics". In your latest code you have labels with underscores instead of spaces. You'll have to be sure your stats files and your labels match.

In post #3, you included a header line in your output; I don't see anything in your latest code that prints that header. And, unless each of your stats files contains all of the sets of statistics and includes them in the same order, what you have shown us will end up printing data for different sets of statistics under each other in the output with no indication of which set they came from. Do each of your stats files contain statistics from all of the possible sets of statistics and are each of those sets of statistics present in the same order in each stats file?

In your latest code you have:

Code:

# name of file being processed
STATS_FILE=$1
# file we are writing to
LOGFILE=$1

which sets both your input file and your output file to be the same input parameter. I'm about 99% sure that isn't what you want.

The cat in your code isn't helping and seems to be working against you. I think you're going to want to end up with something more like:

Code:

... ... ...

# file we are writing to
LOGFILE=$1
# The rest of the operands are stats files we need to read.
shift

awk -v labels="$LABELS" '
    ... ... ...
' "$@" > "$LOGFILE"

Do you want your output fields to be tab separated, or do you want your output fields to be in aligned columns? Note that since your field headers vary in width from 6 characters (e.g., "test_n" to more than 9 characters (e.g. " train_MdAE" and your statistics data all fit in less than 8 characters, the two choices are mutually exclusive. (I.e., you can't have both.)