A Friday 29 January 2010 12:52:01 Francesc Alted escrigué:
> I'm attaching a small script showing you how to do what you are trying to
> do in an 'pytablish' manner. As you will see, it splits the original
> table in one file in two ('slow' and 'fast') in another file.
Ooops! I forgot the handy and efficient `Table.whereAppend()` method. With
it, your problem is reduced to something like:
# Fast particles...
fast = f2.createTable(f2.root, 'fast', table1.description)
table1.whereAppend(fast, "sqrt(x_g**2+y_g**2+z_g**2) > cut")
# Slow particles...
slow = f2.createTable(f2.root, 'slow', table1.description)
table1.whereAppend(slow, "sqrt(x_g**2+y_g**2+z_g**2) <= cut")
Attached is the new version of the script.
Cheers,
--
Francesc Alted
from tables import openFile, Float64Col
N = 1000*1000 # the number of particles
cut = 300000*.1
# The definition or your particle
particle = {
"x_g": Float64Col(shape=(), dflt=0.0, pos=4),
"y_g": Float64Col(shape=(), dflt=0.0, pos=5),
"z_g": Float64Col(shape=(), dflt=0.0, pos=6),
}
# Create initial file and table
f = openFile("/tmp/initial.h5", "w")
table1 = f.createTable(f.root, 'table1', particle)
# Populate the table with some arbitrary values for speed
row = table1.row
for x in xrange(N):
row["x_g"] = x
row["y_g"] = x*2
row["z_g"] = x/2
row.append()
table1.flush()
# Create a new file for the split
f2 = openFile("/tmp/final.h5", "w")
# Now, split the table in two with 'slow' and 'fast' particles each
# Fast particles...
fast = f2.createTable(f2.root, 'fast', table1.description)
table1.whereAppend(fast, "sqrt(x_g**2+y_g**2+z_g**2) > cut")
# Slow particles...
slow = f2.createTable(f2.root, 'slow', table1.description)
table1.whereAppend(slow, "sqrt(x_g**2+y_g**2+z_g**2) <= cut")
f.close()
f2.close()
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