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In the example above, the pulse file is opened, then closed. However no data have been yet fetched from the pulse file.
get
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IMAS data are contained in IDSs which are containers described by the IMAS Data Dictionary. An IDS represents either a Diagnostics (like the 'bolometer' IDS), or a System (like the 'camera_ir'), or a concept like the 'equilibrium' IDS representing the plasma equilibrium.
An IDS can contain 0D (scalar) data or/and arrays with dimensions from 1 to 6.
An IDS exposes the get() operation which reads all IDS data from an opened data_entry (see above).
The code below reads an existing 'magnetics' IDS from a WEST pulse file:
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Number of flux loops = 17 Data of first flux loop = [ 0.00065229 0.00163073 0.00489218 ... -0.01761185 -0.01663342 -0.01500269] Homogeneous time basis = [ 1.83570397 1.86847198 1.90123999 ... 90.13289642 90.16566467 90.19843292] |
put
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In order to write all data contained in a IDS data to the pulse file created previously, we will first use the put() operation which writes all static (non time dependent) AND dynamic data contained present in a the IDS.
Let's add a 'magnetics' IDS to the pulse file previously created.
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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' previously created
data_entry.open()
#creates the 'magnetics' IDS and initializes it
magnetics_ids = imas.magnetics() #creates a 'magnetics' IDS
magnetics_ids.ids_properties.homogeneous_time=1 #setting the homogeneous time (mandatory)
magnetics_ids.ids_properties.comment='IDS created for testing the IMAS Data Access layer' #setting the ids_properties.comment attribute
magnetics_ids.time=np.array([0]) #the time(vector) basis must be not empty if homogeneous_time==1 otherwise an error will occur at runtime
#adding the WEST data of the 10 first flux loops
nb_flux_loops = 10
west_data_entry = imas.DBEntry(imasdef.MDSPLUS_BACKEND, 'west', 54178, 0, 'g2lfleur')
west_magnetics_ids = west_data_entry.get('magnetics', 0) #reading occurrence 0
magnetics_ids.flux_loop.resize(nb_flux_loops)
for i in range(nb_flux_loops):
magnetics_ids.flux_loop[i].flux.data = west_magnetics_ids.flux_loop[i].flux.data #copies data
west_data_entry.close() #closing the WEST pulse file
#writes the 'magnetics' IDS
data_entry.put(magnetics_ids, 0) #writes magnetics data to the data_entry associated to the pulse file. The second argument 0 is the so-called IDS occurrence.
#closes the pulse file associated to the 'data_entry' object
data_entry.close() |
put_slice
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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 frame 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_frames=10 #number of frames to be added
for i in range(nb_frames):
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 slice (frame) to the IDS |