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IMAS data are contained in IDSs which are containers described by the IMAS Data Dictionary (DD). An IDS represents either a tokamak subsystem (like 'camera_ir'), or a concept like the 'equilibrium' IDS representing a plasma equilibrium.
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In the example below, we illustrate the use of put_slice() on a 'camera_visible' IDS which contains the dynamic array of structures 'frame'.
Let's first have a look to the Data Dictionary of the 'camera_visible' IDS description:
As indicated in the DD description, 'frame(itime)' is a dynamic data structure representing a set of frames.
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Adding a time slice using put_slice() on the 'camera_visible' will have for effect to add a new element to the dynamic array 'frame', that is, a new frame for a given time is appended to the array of structures 'frame'.
The example below shows how to add few time slices to the 'camera_visible' IDS, for channel 0 and detector 0:
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import imas
import getpass
import numpy as np
from imas import imasdef
#creates the Data Entry object 'data_entry' associated to the pulse file with shot=15000, run=1, belonging to database 'data_access_tutorial' of the current user, using the MDS+ backend
data_entry = imas.DBEntry(imasdef.MDSPLUS_BACKEND, 'data_access_tutorial', 15000, 1, user_name=getpass.getuser())
#opens the pulse file associated to the data_entry object
data_entry.open()
#creates the 'magnetics' IDS and initializes it
camera_visible_ids = imas.camera_visible()
camera_visible_ids.ids_properties.homogeneous_time = 1
camera_visible_ids.channel.resize(1) #using only 1 channel (channel 0) for this example
camera_visible_ids.channel[0].detector.resize(1) #using only 1 detector for channel 0
camera_visible_ids.channel[0].detector[0].frame.resize(1) #the array of structure 'frame' contains only 1 element, it is the slice to be appended to the IDS
X = 3 #number of horizontal pixels in the frame
Y = 5 #number of vertical pixels in the frame
camera_visible_ids.channel[0].detector[0].frame[0].image_raw.resize(X,Y) #setting the size of the image of the frame
camera_visible_ids.time.resize(1) #the time vector contains only 1 element, it is the time of the slice
nb_slices=10 #number of time slices to be added
for i in range(nb_slices):
camera_visible_ids.time[0] = float(i) #time of the slice
for j in range(X):
for k in range(Y):
camera_visible_ids.channel[0].detector[0].frame[0].image_raw[j,k] = float(j + k + i) #image_raw is a 2D array containing the data (pixels) of the frame
if i==0:
data_entry.put(camera_visible_ids) #the first frame has to be added using put() in order to store static data as well
else:
data_entry.put_slice(camera_visible_ids) #appending the the slice to the IDS
#closes the pulse file associated to the 'data_entry' object
data_entry.close() |
Let's check the time slices we have just appended to the 'camera_visible' IDS using the code below:
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import imas
import getpass
from imas import imasdef
data_entry = imas.DBEntry(imasdef.MDSPLUS_BACKEND, 'data_access_tutorial', 15000, 1, user_name=getpass.getuser())
#opens the pulse file associated to the Data Entry object 'data_entry' previously created
data_entry.open()
#reads the 'magnetics' IDS using get()
camera_visible_ids= data_entry.get('camera_visible',0)
#prints some IDS attributes
print('homogeneous_time = ', camera_visible_ids.ids_properties.homogeneous_time)
for i in range(3):
print("Frame : ", i)
print(camera_visible_ids.channel[0].detector[0].frame[i].image_raw) #prints the content of this 2D array
print("-----")
#closes the pulse file associated to the 'data_entry' object
data_entry.close() |
Running the code above gives the following ouptut:
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homogeneous_time = 1
Frame : 0
[[0 1 2 3 4]
[1 2 3 4 5]
[2 3 4 5 6]]
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Frame : 1
[[1 2 3 4 5]
[2 3 4 5 6]
[3 4 5 6 7]]
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Frame : 2
[[2 3 4 5 6]
[3 4 5 6 7]
[4 5 6 7 8]]
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get_slice
Let's consider an IDS containing dynamic data as the 'camera_visible' IDS described above.
Calling get_slice() will slice (at a given time and for a given interpolation method) each dynamic data structure contained in the IDS, static data structures are ignored. Therefore, get_slice() returns just a