=======================
 mergeshift.awk 
=======================
#!/usr/bin/gawk -f
#
#  mergeshift.awk   collect shifts from various shift lists
#                   keeps latest entry, so give your most 
#                   accurate shifts last
#
#  NB still expects old type shift list format with mid,wid/2
#     instead of lo,hi,spread
#  see also : ass2shift.awk
#
# ?? select residue format for reading chemical shifts (shift header?)
# ?? grepping line with eg:10 ala hh21 
#
# ?? make sure to include h2o { 
#
# -v add_err=0.05 add shift-error of 0.05 to shifts of file n
# -v def_err=0.05 default shift-error of 0.05 for shifts of file n
# -v min_err=0.05 minimal shift-error of 0.05 for shifts of file n
# input format :
# 34 val  ha    5.445 0.013  ## -> read ppm value + error 
# deleteshift  34 val  ha  ## -0> delete ppmvalue from the list