Yade

calculate mass content of a group of particles through something like label

Asked by Leonard

Hi,
I'd like to calculate the mass content of a group of spheres, as far as I know, we can obtain a mass of one sphere by:
O.bodies[id].state.mass
I'd like to ask that if we can obtain the mass of a group of spheres like: appending some spheres with a same label, like:
O.append(sphere((x1,y1,z1),radius=radius,label="label1"))
O.append(sphere((x2,y2,z2),radius=radius,label="label1"))
O.append(sphere((x3,y3,z3),radius=radius,label="label2"))
O.append(sphere((x4,y4,z4),radius=radius,label="label2"))
then we can obtain the total mass of spheres with label1, and label2 respectively?
I have tried in Yade, it seems that we can not give each sphere a label, is there any way that we can classify the spheres to different groups so that we can just loop in one group of spheres to calculate the mass?
Thanks in advance!

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gaoxuesong
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Best gaoxuesong (260582472-9) said : 		#1

Hi,

    The possible way i think is that using different lists to save the sphere's id of different groups and do loop in each list.
## group 1 ##
list1 = []
list1.append(O.append(sphere((x1,y1,z1),radius=radius1)))
...
## group 2 ##
list2 = []
list2.append(O.append(sphere((x2,y2,z2),radius=radius2)))
...
## calculate the mass of different groups ##
masstotal1 = 0
for each in list1:
    masstotal1 + = O.bodies[each].state.mass
masstotal2 = 0
for each in list2:
    masstotal2 + = O.bodies[each].state.mass

## ends ##

Cheers,
Xuesong

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Leonard (z2521899293) said : 		#2

Hi xuesong,
Many thanks for your solution.
Your approach works very well, while one point should be noted that:
--->>The possible way i think is that using different lists to save the sphere's id of different groups and do loop in each list.
--->>## group 1 ##
--->>list1 = []
--->>list1.append(O.append(sphere((x1,y1,z1),radius=radius1)))
In this way, the list1 stores not the id of sphere, but the sphere body, so for the next code:
--->>## calculate the mass of different groups ##
--->>masstotal1 = 0
--->>for each in list1:
    --->>masstotal1 + = O.bodies[each].state.mass
May should be:
masstotal1 = 0
for each in list1:
    masstotal1 + = each.state.mass

Thanks again for your help, I just mention it more clearly for other beginners.

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Leonard (z2521899293) said : 		#3

Thanks gaoxuesong, that solved my question.

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Leonard (z2521899293) said : 		#4

Hi xuesong,
I am sorry that I make a wrong answer in #2.
You are right.
-->>list1.append(O.bodies.append(sphere((x1,y1,z1),radius=radius1)))
In this way, the list1 stores the id of the sphere.
The reason why I make the mistake is I did like this:
-->>s1=O.bodies.append(sphere((x1,y1,z1),radius=radius1))
-->>list1=[]
-->>list1.append(s1)
then in this way, the list1 stores the body of sphere.
Thank you again.
Cheers,
Leonard

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gaoxuesong (260582472-9) said : 		#5

You are welcome. However, in the way as you said,
###
-->>s1=O.bodies.append(sphere((x1,y1,z1),radius=radius1))
-->>list1=[]
-->>list1.append(s1)
###
list1 also stores the id of a body. In this way, it stores the body.
-->>s1=O.bodies.append(sphere((x1,y1,z1),radius=radius1))
-->>list1=[]
-->>list1.append(O.bodies[s1])
###
one thing to be addressed is that the return value of the O.bodies.append() is the body's id not the body itself.
 best,
Xuesong