Reply To: export cells into an existing gds

[Ronald]

Dear Paul,

There is a special mechanism in Nazca to replace parametric and/or static cells.
In case of static cells the example below shows how you can use on or more GDS library files as a source to replace cells in your original gds by name. It doesn’t matter how many or how deep in the tree those cells are:

import nazca as nd

# File name of gds input.
gdsin = 'example.gds'

# a list of scell (static cell) libraries:
# and a cellmap for each library file: { : }
# where resides in gdsin and in the lib.
scell_libs = {
    'scell_lib1.gds': {
        'C': 'newC',
         # other cell name mappings
    },
    # other libs and mappings as needed
}

# Replace cells and write output to a new gds file (gdsin will not be changed).
nd.replaceCells(
    gdsin=gdsin,
    ScellMapping=scell_libs
)

Starting with the following cell structure

A
  B
  C
D

the replacement C -> newC gives

A
  B
  newC
D

Although A has different content now, effectively only its references to C have been changed. So, I kept A’s original name.

In contrast, if you replace A -> newA you get

newA
  # branches in newA
D

If you replace A by newA the substructure (the tree) of A is irrelevant as it is replaced as a whole; You remove the whole branch behind the cut. Cell newA can be a cell or tree of cells.

If newA would look like

newA
  C

then the replacement result A -> newA is

newA
  C
D

If newA would look like

newA
  newC

then the replacement result is

newA
  newC
D

If you have two libraries like

# lib1.gds:
NewA
  C

# lib2.gds:
newC

then you would use

gdsin = 'example.gds'

scell_libs = {
    'lib1.gds': {'A': 'newA'},
    'lib2.gds': {'C': 'newC'}
}

nd.replaceCells(
    gdsin=gdsin,
    ScellMapping=scell_libs
)

to obtain

newA
  newC
D

Note: Since Python 3.7 dictionaries are ordered as a language feature, which is important as replacement is not commutative in the order of the libraries (in ‘scell_libs’ above). In earlier Python versions you would make consecutive calls of nd.replaceCells() with one library at a time to ensure the library order.

Ronald