Replace nulls in list with previous item

Lists-Logic
1

I have a list that has some null value interspersed in it. I would like to replace nulls with the previous value actual value. Note that there can be multiple nulls in a row.

thanks much
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3

@Jpeele_JDB See if this helps:

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image639Ă—533 35.8 KB 

toNestList = lambda x: x if any(isinstance(i, list) for i in x) else [x]
OUT = [[x if x else i[j-1] for j,x in enumerate(i)] for i in toNestList(IN[0])]

This would not work as intended if you have 2 nulls back to back or if index 0 is a null.

1 Like
4

@Jpeele_JDB And this should take care of the back to back nulls:

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toNestList = lambda x: x if any(isinstance(i, list) for i in x) else [x]
OUT = []
for i in toNestList(IN[0]):
	out = []
	for x in i:
		if x:
			out.append(x)
		else:
			out.append(out[-1])
	OUT.append(out)

This would not work as intended if index 0 is a null.

3 Likes
5

Pythonless option. I use this in my ReplaceNulls node in Crumple.

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2 Likes
6

@GavinCrump That’s the 1st thing I tried but missed the @L2 in haste and assumed “if” didn’t work as usual! Thanks for pointing it out.

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image955Ă—660 51.3 KB

1 Like
7

If very rarely works (as desired), no worries - I quite like the Python approach as well!

1 Like
8

I think Python approach is better compare to Node,
because if 2 consecutive null is coming in a list than “List.ShiftIndices” Will not give appropriate,

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1 Like
9

Ah yes sorry i misunderstood the intent or your script (I overlooked the shift). The Python approach is best here, you’re right.