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Each flux structure contains a FLT_1D data array named 'data', a INT_1D array named ' ' validity_timed', a INT_0D scalar named 'validity', a FLT_1D data array named 'time'.
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Let's add a 'magnetics' IDS to the pulse file previously created in section 1.1.1.
The first part of the code below is opening a data_entry then a magnetics IDS is created and written to the data_entry using the put() operation:
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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 if 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 magnetics_ids.ids_properties.homogeneous_time==0: magnetics_ids.flux_loop[i].flux.time = west_magnetics_ids.flux_loop[i].flux.time #copies the time basis in case WEST IDS arrays don't accept a common time basis if west_magnetics_ids.ids_properties.homogeneous_time==1: magnetics_ids.time = west_magnetics_ids.time #copies the 'root' time basis in case WEST IDS arrays accept a common time basis west_data_entry.close() |
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#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
An IDS containg dynamic data structures can be built progressively using data time slices.
A dynamic data structure:
- is either an array with type INT_nD or FLT_nD where n=1 to 6, which accepts a time coordinate
- or a so-called dynamic array of structures AOS[i] where i runs along a time index
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 description, 'frame(itime)' is a dynamic data structure representing a set of frames.
Each element of 'frame' is a structure containing:
- 'image_raw', a INT_2D array
- 'radiance', a FLT_2D array
- 'time', a time basis (used only in case the IDS has no common time basis)
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 is appended to the array of structures 'frame'.
The example below shows how to add time slices to the 'camera_visible' IDS, for channel 0 and detector 0:
- The number of time slices to be appended is given by the variable 'nb_frames'.
- Each time slice is represented by the data structure: camera_visible_ids.channel[0].detector[0].frame[0]
- Only the data of the INT_2D 'image_raw" and the data of global time basis 'time' (since the 'camera_visible' has homogeneous_time = 1) are populated in the time slice to be appended
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| The first time slice needs to be appended using a call to put(), not put_slice(). Only subsequent time slices are appended using put_slice(). |
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Time slices should be always appended using increasing time value. |
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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 |
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