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"""Small example showing the use of nested types in PyTables.
The program creates an output file, 'nested-tut.h5'. You can view it
with ptdump or any HDF5 generic utility.
:Author: F. Alted
:Date: 2005/06/10
"""
import numpy as np
import tables as tb
# '-**-**-**-**- The sample nested class description -**-**-**-**-**-'
class Info(tb.IsDescription):
"""A sub-structure of Test"""
_v_pos = 2 # The position in the whole structure
name = tb.StringCol(10)
value = tb.Float64Col(pos=0)
colors = tb.Enum(["red", "green", "blue"])
class NestedDescr(tb.IsDescription):
"""A description that has several nested columns."""
color = tb.EnumCol(colors, "red", base="uint32")
info1 = Info()
class IInfo2(tb.IsDescription):
_v_pos = 1
name = tb.StringCol(10)
value = tb.Float64Col(pos=0)
class IInfo3(tb.IsDescription):
x = tb.Float64Col(dflt=1)
y = tb.UInt8Col(dflt=1)
print()
print("-**-**-**-**-**-**- file creation -**-**-**-**-**-**-**-")
filename = "nested-tut.h5"
print("Creating file:", filename)
fileh = tb.open_file(filename, "w")
print()
print("-**-**-**-**-**- nested table creation -**-**-**-**-**-")
table = fileh.create_table(fileh.root, "table", NestedDescr)
# Fill the table with some rows
row = table.row
for i in range(10):
row["color"] = colors[["red", "green", "blue"][i % 3]]
row["info1/name"] = "name1-%s" % i
row["info2/name"] = "name2-%s" % i
row["info2/info3/y"] = i
# All the rest will be filled with defaults
row.append()
table.flush() # flush the row buffer to disk
print(repr(table.nrows))
nra = table[::4]
print(repr(nra))
# Append some additional rows
table.append(nra)
print(repr(table.nrows))
# Create a new table
table2 = fileh.create_table(fileh.root, "table2", nra)
print(repr(table2[:]))
# Read also the info2/name values with color == colors.red
names = [x["info2/name"] for x in table if x["color"] == colors.red]
print()
print("**** info2/name elements satisfying color == 'red':", repr(names))
print()
print("-**-**-**-**-**-**- table data reading & selection -**-**-**-**-**-")
# Read the data
print()
print("**** table data contents:\n", table[:])
print()
print("**** table.info2 data contents:\n", repr(table.cols.info2[1:5]))
print()
print(
"**** table.info2.info3 data contents:\n",
repr(table.cols.info2.info3[1:5]),
)
print("**** _f_col() ****")
print(repr(table.cols._f_col("info2")))
print(repr(table.cols._f_col("info2/info3/y")))
print()
print("-**-**-**-**-**-**- table metadata -**-**-**-**-**-")
# Read description metadata
print()
print("**** table description (short):\n", repr(table.description))
print()
print("**** more from manual, period ***")
print(repr(table.description.info1))
print(repr(table.description.info2.info3))
print(repr(table.description._v_nested_names))
print(repr(table.description.info1._v_nested_names))
print()
print("**** now some for nested records, take that ****")
print(repr(table.description._v_nested_descr))
print(
repr(np.rec.array(None, shape=0, dtype=table.description._v_nested_descr))
)
print(
repr(
np.rec.array(
None, shape=0, dtype=table.description.info2._v_nested_descr
)
)
)
print()
print("**** and some iteration over descriptions, too ****")
for coldescr in table.description._f_walk():
print("column-->", coldescr)
print()
print("**** info2 sub-structure description:\n", table.description.info2)
print()
print("**** table representation (long form):\n", repr(table))
# Remember to always close the file
fileh.close()
|
