random notes

one way to make existing "time" dimension to be "unlimited": 

cdo seltimestep,1/12 ifile ofile

where 1/12 is the first and last indices of your time record. 

Ref: https://code.zmaw.de/boards/1/topics/798

 1057  cdo seltimestep,1/1 sic_G10010_SIBT1850_v1.1-naa_icecon.nc4 sic.nc
 1058  cdo seltimestep,1/1 sit_G10010_SIBT1850_v1.1-naa_icecon.nc4 sic.nc
 1059  cdo seltimestep,1/1 sit_PIOMAS_1979_2013-naa_arlan.nc4 sit.nc 

Add all variables in sic.nc to sit.nc
 1062  ncks -h -A sic.nc sit.nc 

Remove time_counter dimension from the lists of dimensions and variables. 
 1065  ncwa -a time_counter sit.nc sit2.nc

Same names (labels) but different IDs for nodes in PyGraphviz:

add_node(1,label=A)

add_node(2,label=B)

add_node(3,label=A)

will create three nodes consisting of two As and one B. 

Ref: http://stackoverflow.com/questions/15711909/how-to-create-duplicate-nodes-in-pygraphviz