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import sys
from time import time
import numpy as np
import tables as tb
N = 200
NBUNCH = 100_000_000
NREADS = 100_000
filename = "read-table.h5"
class Particle(tb.IsDescription):
lati = tb.Int32Col()
longi = tb.Int32Col()
pressure = tb.Float32Col()
temperature = tb.Float32Col()
if len(sys.argv) > 1 and sys.argv[1] == "w":
# Open a file in "w"rite mode
print(f"Creating {filename} with {NBUNCH * N / 1_000_000} Mrows...")
t0 = time()
fileh = tb.open_file(filename, mode="w")
# Create a new table in newgroup group
table = fileh.create_table(
fileh.root,
"table",
Particle,
"A table",
tb.Filters(complevel=1, complib="blosc2"),
expectedrows=NBUNCH * N,
)
# A bunch of particles
particles = np.zeros(NBUNCH, dtype=table.dtype)
# Fill the table with N chunks of particles
for i in range(N):
table.append(particles)
table.flush()
print(f"Time to create: {time() - t0:.3f}s")
else:
fileh = tb.open_file(filename)
table = fileh.root.table
t0 = time()
idxs_to_read = np.random.randint(0, NBUNCH, NREADS)
print(f"Time to create indexes: {time() - t0:.3f}s")
print(f"Reading {NREADS / 1_000} Krows...")
t0 = time()
for i in idxs_to_read:
row = table[i]
print(f"Time to read: {time() - t0:.3f}s")
fileh.close()
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