Python write vector attribute to text file

[philpappas]

Hello,

i think this will be simple for someone more experienced.

i have two vector primitive attributes and i want to write them in a text file so-------> v1.x, v1.y v1.z, n1.x, n1.y ,n1.z , v2.x, v2.y v2.z, ....etc  for each primitive

 

this is how far i am now

 

#############  READ ATTRIBUTES  ######################

for prim in geo.prims() :
    pos = hou.Vector3(prim.attribValue('pos'))
    dir = hou.Vector3(prim.attribValue('dir'))
    data = str(pos) + "," + str(dir)    
    
#############  WRITE TO TEXT FILE ######################

myfile = '$HIP/lattice.txt'

with open(myfile, 'w') as f:
    for item in data:
        f.write("%s\n" % item)

spits out this nonsense, splits every character to a new line

[
-
1
7
5
2
,
 
-
1
1
9
.
0
3
,
 
1
4
6
4
]
,
[
0
,
 
3
0
.
9
0
1
4
,
 
0
]

 

 

[jeremiah]

 

5 hours ago, philpappas said:

for prim in geo.prims() :
    pos = hou.Vector3(prim.attribValue('pos'))
    dir = hou.Vector3(prim.attribValue('dir'))
    data = str(pos) + "," + str(dir)    

Not sure if these lines are working, but it seems to me that the value of "data" would be a string. Therefore, when you loop through "data", "item" would be each characters in the string. Hope I could be misunderstanding..

[Stalkerx777]

import hou
import numpy as np

geo = hou.node('/obj/geo1/torus').geometry()

# Read the attributes into numpy arrays
pos_array = np.frombuffer(geo.primFloatAttribValuesAsString('pos'), dtype=np.float32)
dir_array = np.frombuffer(geo.primFloatAttribValuesAsString('dir'), dtype=np.float32)

# Split the array by 3
pos_array = np.array_split(pos_array, pos_array.size/3)
dir_array = np.array_split(dir_array, dir_array.size/3)

# Stack the arrays (similar to python zip())
stack = np.column_stack((pos_array, dir_array))
# Make a single continuios array of form pos.x pos.y pos.z dir.x dir.y dir.z
final = stack.flatten()
# Save to a file with float precision = 3
np.savetxt('c:/temp/foo.txt', final, fmt='%.3f', newline=' ')

 

If you need speeeeeeeed  

[philpappas]

On 10/23/2019 at 7:04 AM, Stalkerx777 said:

If you need speeeeeeeed 

thanks a lot, it works (not so fast though if you have thousands of values )

import hou
import numpy as np

node = hou.pwd() # get the current node
geo = node.geometry() #get geometry of node

# Read the attributes into numpy arrays
pos_array = np.frombuffer(geo.pointFloatAttribValuesAsString('pos'), dtype=np.float32)
dir_array = np.frombuffer(geo.pointFloatAttribValuesAsString('dir'), dtype=np.float32)

i read the point attributes directly from the python node, absolute paths wont help a lot because i'm working in an asset.

i also found this blog and the code takes about the same time to write the text file.

http://astroukoff.blogspot.com/2018/05/data-from-houdini-to-unity-via-text-file.html

this is the code i used (one attribute at a time though):

node = hou.pwd() # get the current node
geo = node.geometry() #get geometry of node

myTxt = file("$HIP/POSITION.txt", "w") #create file, w = write mode

for point in geo.points(): #iterate through each geo point
    pos = point.attribValue("pos") #save position in a pos var
    s = str(pos) #write position to s string
    myTxt.write(s) #write s string into a file

myTxt.close()