Error encountered during pcell instantiation??

Hi Messi,

You can think of a table as a "hash table" or "associative array" as in other languages. The idea is that it allows you to have something like an array, except the index can be anything that you like. It could be a string, or a database object, or a list - whatever. Effectively what happens is that it encodes (or hashes) the key (the index), and then uses that to approximately address the entry in the table, and from there it can do a search to find the exact match (this is a very simplified explanation - you might want to look at http://en.wikipedia.org/wiki/Hash_tables for a bit more insight). The benefit of all of this is that it allows for a dynamic amount of keys - you don't have to pre-allocate space (like you would with a normal array), and it also has fast access (not quite random access, but not far off) compared with other dynamic structures such as lists (which are sequential). The downside is that the structure is unordered, and so whilst easy to visit all the keys in the table, there is no record of the order in which they were added.

To illustrate it:

myTab=makeTable("myTableName")

Now, the first argument to makeTable is really unimportant. The only thing it serves is that the print representation of your variable myTab will now show:

table:myTableName

There is no requirement for the first argument to be unique - as all it is used for is the print representation as above.

Having created the table, you can now add values into it:

myTab[2]="test"
myTab["hello world"]=198
myTab[geGetEditCellView()]=car(geGetSelSet())
myTab[list(1 2)]='someSymbol

As you can see, the keys (the index in the array syntax) can be any data type, as can the values. You retrieve the values by using myTab["hello world"] (say) - giving the same key.

If you try to refer to a key that doesn't exist (e.g. myTab[5]) it will return the symbol unbound. If that's not what  you want, you can choose when you create the table what value should be returned for any key that doesn't exist. So if I had done myTab=makeTable("myTableName" nil) it would have returned nil or if I'd done myTab=makeTable("myTableName" 0) it would have returned 0. Try this out yourself.

Having built a table, you can visit the contents easily. With the above, for example, I could do:

foreach(key myTab
  printf("KEY: %L  VALUE: %L\n" key myTab[key])
)

and it would print out:

KEY: db:0x12c31d92  VALUE: db:0x14a37532
KEY: 2  VALUE: "test"
KEY: (1 2)  VALUE: someSymbol
KEY: "hello world"  VALUE: 198

There is no guarantee what the order would be here, by the way. It would be consistent within a particular version, but you should never, ever rely on that.

You can also find the keys by doing myTab~>? or the keys and values by doing myTab~>?? . tableToList(myTab) is another way of converting to a list of lists (like an "assoc" list structure).

Here's an example (one we normally use in the training class):

shapeTable=makeTable("shapeCount" 0)
foreach(shape geGetEditCellView()~>shapes
  shapeTable[shape~>objType]=shapeTable[shape~>objType]+1
)
foreach(shapeType shapeTable
  printf("%-20s: %d\n" shapeType shapeTable[shapeType])
)

This will give an output something like:

pathSeg             : 298
path                : 36
rect                : 2376

Now, if you want to read something and keep track of the order, there's nothing to stop you doing this. If you have a file containing:

RUL1 POLY1 WIDTH 0.1
RUL2 POLY1 SPACING 0.5
RUL7 METAL1 WIDTH 0.5
RUL6 METAL1 SPACING 0.6

I've kept it simple for illustration purposes. Then I read this:

; use a structure to bring together both the table and the order list
defstruct(ruleData order table)
ruleInfo=make_ruleData(?order nil ?table makeTable("ruleData" nil))
prt=infile("rule.txt")
when(prt
  while(data=gets(line prt)
    ruleList=parseString(line)
    ruleInfo->order=tconc(ruleInfo->order car(ruleList))
    ruleInfo->table[car(ruleList)]=cdr(ruleList)
  )
)
; because using tconc to build list on order, convert to a normal list
ruleInfo->order=car(ruleInfo->order)
; now print out the contents in order
foreach(key ruleInfo->order
  printf("%s %s\n" key buildString(ruleInfo->table[key]))
)

Of course, you can access an arbitrary rule easily using ruleInfo->table["RUL7"] say.

Hope this helps!

Best Regards,

Andrew.

Hi Messi,

You can think of a table as a "hash table" or "associative array" as in other languages. The idea is that it allows you to have something like an array, except the index can be anything that you like. It could be a string, or a database object, or a list - whatever. Effectively what happens is that it encodes (or hashes) the key (the index), and then uses that to approximately address the entry in the table, and from there it can do a search to find the exact match (this is a very simplified explanation - you might want to look at http://en.wikipedia.org/wiki/Hash_tables for a bit more insight). The benefit of all of this is that it allows for a dynamic amount of keys - you don't have to pre-allocate space (like you would with a normal array), and it also has fast access (not quite random access, but not far off) compared with other dynamic structures such as lists (which are sequential). The downside is that the structure is unordered, and so whilst easy to visit all the keys in the table, there is no record of the order in which they were added.

To illustrate it:

myTab=makeTable("myTableName")

Now, the first argument to makeTable is really unimportant. The only thing it serves is that the print representation of your variable myTab will now show:

table:myTableName

There is no requirement for the first argument to be unique - as all it is used for is the print representation as above.

Having created the table, you can now add values into it:

myTab[2]="test"
myTab["hello world"]=198
myTab[geGetEditCellView()]=car(geGetSelSet())
myTab[list(1 2)]='someSymbol

As you can see, the keys (the index in the array syntax) can be any data type, as can the values. You retrieve the values by using myTab["hello world"] (say) - giving the same key.

If you try to refer to a key that doesn't exist (e.g. myTab[5]) it will return the symbol unbound. If that's not what  you want, you can choose when you create the table what value should be returned for any key that doesn't exist. So if I had done myTab=makeTable("myTableName" nil) it would have returned nil or if I'd done myTab=makeTable("myTableName" 0) it would have returned 0. Try this out yourself.

Having built a table, you can visit the contents easily. With the above, for example, I could do:

foreach(key myTab
  printf("KEY: %L  VALUE: %L\n" key myTab[key])
)

and it would print out:

KEY: db:0x12c31d92  VALUE: db:0x14a37532
KEY: 2  VALUE: "test"
KEY: (1 2)  VALUE: someSymbol
KEY: "hello world"  VALUE: 198

There is no guarantee what the order would be here, by the way. It would be consistent within a particular version, but you should never, ever rely on that.

You can also find the keys by doing myTab~>? or the keys and values by doing myTab~>?? . tableToList(myTab) is another way of converting to a list of lists (like an "assoc" list structure).

Here's an example (one we normally use in the training class):

shapeTable=makeTable("shapeCount" 0)
foreach(shape geGetEditCellView()~>shapes
  shapeTable[shape~>objType]=shapeTable[shape~>objType]+1
)
foreach(shapeType shapeTable
  printf("%-20s: %d\n" shapeType shapeTable[shapeType])
)

This will give an output something like:

pathSeg             : 298
path                : 36
rect                : 2376

Now, if you want to read something and keep track of the order, there's nothing to stop you doing this. If you have a file containing:

RUL1 POLY1 WIDTH 0.1
RUL2 POLY1 SPACING 0.5
RUL7 METAL1 WIDTH 0.5
RUL6 METAL1 SPACING 0.6

I've kept it simple for illustration purposes. Then I read this:

; use a structure to bring together both the table and the order list
defstruct(ruleData order table)
ruleInfo=make_ruleData(?order nil ?table makeTable("ruleData" nil))
prt=infile("rule.txt")
when(prt
  while(data=gets(line prt)
    ruleList=parseString(line)
    ruleInfo->order=tconc(ruleInfo->order car(ruleList))
    ruleInfo->table[car(ruleList)]=cdr(ruleList)
  )
)
; because using tconc to build list on order, convert to a normal list
ruleInfo->order=car(ruleInfo->order)
; now print out the contents in order
foreach(key ruleInfo->order
  printf("%s %s\n" key buildString(ruleInfo->table[key]))
)

Of course, you can access an arbitrary rule easily using ruleInfo->table["RUL7"] say.

Hope this helps!

Best Regards,

Andrew.