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"""This program shows the different protections that PyTables offer to the user
in order to insure a correct data injection in tables.
Example to be used in the second tutorial in the User's Guide.
"""
import numpy as np
import tables as tb
# Describe a particle record
class Particle(tb.IsDescription):
name = tb.StringCol(itemsize=16) # 16-character string
lati = tb.Int32Col() # integer
longi = tb.Int32Col() # integer
pressure = tb.Float32Col(shape=(2, 3)) # array of floats
# (single-precision)
temperature = tb.Float64Col(shape=(2, 3)) # array of doubles
# (double-precision)
# Native NumPy dtype instances are also accepted
Event = np.dtype(
[
("name", "S16"),
("TDCcount", np.uint8),
("ADCcount", np.uint16),
("xcoord", np.float32),
("ycoord", np.float32),
]
)
# And dictionaries too (this defines the same structure as above)
# Event = {
# "name" : StringCol(itemsize=16),
# "TDCcount" : UInt8Col(),
# "ADCcount" : UInt16Col(),
# "xcoord" : Float32Col(),
# "ycoord" : Float32Col(),
# }
# Open a file in "w"rite mode
fileh = tb.open_file("tutorial2.h5", mode="w")
# Get the HDF5 root group
root = fileh.root
# Create the groups:
for groupname in ("Particles", "Events"):
group = fileh.create_group(root, groupname)
# Now, create and fill the tables in Particles group
gparticles = root.Particles
# Create 3 new tables
for tablename in ("TParticle1", "TParticle2", "TParticle3"):
# Create a table
table = fileh.create_table(
"/Particles", tablename, Particle, "Particles: " + tablename
)
# Get the record object associated with the table:
particle = table.row
# Fill the table with 257 particles
for i in range(257):
# First, assign the values to the Particle record
particle["name"] = "Particle: %6d" % (i)
particle["lati"] = i
particle["longi"] = 10 - i
# Detectable errors start here. Play with them!
particle["pressure"] = i * np.arange(2 * 4).reshape(2, 4) # Incorrect
# particle['pressure'] = i * arange(2 * 3).reshape(2, 3) # Correct
# End of errors
particle["temperature"] = i**2 # Broadcasting
# This injects the Record values
particle.append()
# Flush the table buffers
table.flush()
# Now, go for Events:
for tablename in ("TEvent1", "TEvent2", "TEvent3"):
# Create a table in Events group
table = fileh.create_table(
root.Events, tablename, Event, "Events: " + tablename
)
# Get the record object associated with the table:
event = table.row
# Fill the table with 257 events
for i in range(257):
# First, assign the values to the Event record
event["name"] = "Event: %6d" % (i)
event["TDCcount"] = i % (1 << 8) # Correct range
# Detectable errors start here. Play with them!
event["xcoor"] = float(i**2) # Wrong spelling
# event['xcoord'] = float(i**2) # Correct spelling
event["ADCcount"] = "sss" # Wrong type
# event['ADCcount'] = i * 2 # Correct type
# End of errors
event["ycoord"] = float(i) ** 4
# This injects the Record values
event.append()
# Flush the buffers
table.flush()
# Read the records from table "/Events/TEvent3" and select some
table = root.Events.TEvent3
events = [
particle["TDCcount"]
for particle in table
if particle["ADCcount"] < 20 and 4 <= particle["TDCcount"] < 15
]
print("Last record ==>", events[-1])
print("Selected values ==>", events)
print("Total selected records ==> ", len(events))
# Finally, close the file (this also will flush all the remaining buffers!)
fileh.close()
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