List gets shortened when there is no value at index 0


I noticed a strange behaviour, no clue if it’s intended like that but it took me forever to find that mistake in my script and I wonder how to solve it without hardcoding something.

I get all kinds of parameter values from a list of elements and one of the lists starts without a value at index 0. The other lists also have no value somewhere in the list, but all of them have a value at index 0.

The strange thing that happens now is, when I import the list with no value at index 0 into a Python script-node it gets shorter than the other lists with a value at index 0. That ruins my for-loops…
When I use a string from array-node I get the same effect:

Is that a bug or why does it shorten the list if it starts without a value but doesn’t care for the value later on? Any solution how to solve it?

Thanks in advance :slight_smile:

Can you post a graph with the minimal python node to reproduce the error?

1 Like

Puh, it’s quite a long python code, with 8 other inputs… Not sure if that helps.

I just found that there is a value at index 0, if I list all indices with a string = “” it shows up:

# Load the Python Standard and DesignScript Libraries
import sys
import clr
from Autodesk.DesignScript.Geometry import *

# The inputs to this node will be stored as a list in the IN variables.
dataEnteringNode = IN

# inputs that are necessary to determine the type of the door
width = IN[0]
height = IN[1]
family = IN[2]
construction = IN[3]
dicti = IN[4]
fire = IN[5]
acustics = IN[6]
beslag = IN[7]
ending = IN[8]

# dictionary with all doortypes
master = {}

# debug
errors = []
list_out = []
all_concat_name = []

# Place your code below this line
for i in range(len(width)):
	# concatenate all types to create the later dictionary
	concat_name = str(width[i]) + "-" + \
		str(height[i]) + "-" + \
		str(family[i]) + "-" + \
		str(construction[i]) + "-" + \
		str(fire[i]) + "-" + \
		str(acustics[i]) + "-" + \


	if entry already exists, just add the element
	if concat_name in master.keys():
	elif construction[i] not in dicti.keys():								# if the Construction Type is not named the element will end up on a "error-list"
	else:																	# otherwise it creates a new key with a unique number for the door type
		existing_entries = []      											# empty list of exisiting values
		string = dicti[construction[i]] + str(width[i])[:-2]                # the most basic string of the value, without ending (e.g. "GP10")

		# gathering all values in the littera dictionary (e.g. GP10A, GP10B...)
		all_values = master.values()

		# compare if the value is in the list of all_values and append it to the list of existing_entries
		for value in list(all_values):
			if string in value:

		# if the existing_entries is empty (no similar doortype and width), it will create a whole new entry with "A" as first ending
		if len(existing_entries) == 0:
			# parse the value to the export
			new_entry = string + "A"
			if len(existing_entries) > 1:										# if the list has more than one entry it sorts the list and uses the last value of the the list to continue
				# sort the list
				# use the last entry of the sorted_list
				existing_entry = existing_entries[-1]
				# last letter of the existing_entry
				last_letter = existing_entry[-1]
				# increment the last letter
				new_last_letter = chr(ord(last_letter)+1)
				new_entry = string + new_last_letter
			else:																# otherwise it skips sorting and uses the only entry in the list, at index 0
				existing_entry = existing_entries[0]
				new_entry = string + chr(ord(existing_entry[-1])+1)

		# the new entry is a concatenation of string (GP10) and the incremented ending of the last element in the list
		master[concat_name] = new_entry

# Assign your output to the OUT variable.
OUT = [list_out,errors,master.values(),all_concat_name]

I tried to reproduce it, but now it’s not happening anymore… Sorry for the fuzz, no clue what made the difference.

1 Like

Likely your dynamo VM was in a bad state. Open and closing the graph, or open and closing Dynamo, or sometimes restarting your CPU will sometimes resolve these kinds of issues. :slight_smile: