Sergio Hernández Cadena / gammalib

Commit 694e75fce0d2c9dcbe993ccf2c8e03cfa7022a52

Authored by Jürgen Knödlseder
1 parent b1125e94

Add matrix handling howto.

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examples/python/matrix_howto.py 0 → 100755
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  1 +#! /usr/bin/env python
  2 +# ==========================================================================
  3 +# Scope
  4 +#
  5 +# This script provides an example for matrix handling with GammaLib
  6 +#
  7 +# Usage
  8 +# ./matrix_howto.py
  9 +#
  10 +# -------------------------------------------------------------------------
  11 +#
  12 +# Copyright (C) 2013 Juergen Knoedlseder
  13 +#
  14 +# This program is free software: you can redistribute it and/or modify
  15 +# it under the terms of the GNU General Public License as published by
  16 +# the Free Software Foundation, either version 3 of the License, or
  17 +# (at your option) any later version.
  18 +#
  19 +# This program is distributed in the hope that it will be useful,
  20 +# but WITHOUT ANY WARRANTY; without even the implied warranty of
  21 +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  22 +# GNU General Public License for more details.
  23 +#
  24 +# You should have received a copy of the GNU General Public License
  25 +# along with this program. If not, see <http://www.gnu.org/licenses/>.
  26 +#
  27 +# ==========================================================================
  28 +import gammalib
  29 +
  30 +
  31 +# =========================== #
  32 +# Illustrates matrix handling #
  33 +# =========================== #
  34 +def handle_matrix():
  35 + """
  36 + Illustrates the handling of matrix. Although we use in this example the
  37 + GMatrix class, the same operations can be performed on a sparse matrix
  38 + GMatrixSparse or a symmetric matrix GMatrixSymmetric.
  39 + """
  40 + # Create matrix with 4 rows and 5 columns
  41 + matrix = gammalib.GMatrix(4,5)
  42 +
  43 + # Get matrix attributes
  44 + number_of_rows = matrix.rows() # Will be 4
  45 + number_of_columns = matrix.columns() # Will be 5
  46 + number_of_elements = matrix.size() # Will be 20=4*5
  47 + matrix_fill = matrix.fill() # Will be 0
  48 + matrix_minimum = matrix.min() # Will be 0
  49 + matrix_maximum = matrix.max() # Will be 0
  50 + matrix_sum = matrix.sum() # Will be 0
  51 +
  52 + # Dump some information
  53 + print("Attributes of an empty GMatrix:")
  54 + print(gammalib.parformat("Matrix rows")+str(number_of_rows))
  55 + print(gammalib.parformat("Matrix columns")+str(number_of_columns))
  56 + print(gammalib.parformat("Matrix elements")+str(number_of_elements))
  57 + print(gammalib.parformat("Matrix fill")+str(matrix_fill))
  58 + print(gammalib.parformat("Smallest matrix element")+str(matrix_minimum))
  59 + print(gammalib.parformat("Largest matrix element")+str(matrix_maximum))
  60 + print(gammalib.parformat("Sum of all element")+str(matrix_sum))
  61 +
  62 + # Set all matrix elements to 2.0
  63 + matrix.set(2.0)
  64 +
  65 + # Now set all matrix elements to specific values
  66 + for row in range(matrix.rows()):
  67 + for column in range(matrix.columns()):
  68 + matrix[row,column] = row + column*matrix.rows() + 1.5
  69 +
  70 + # Get matrix attributes
  71 + matrix_fill = matrix.fill() # Will be 1
  72 + matrix_minimum = matrix.min() # Will be 1.5
  73 + matrix_maximum = matrix.max() # Will be 20.5
  74 + matrix_sum = matrix.sum() # Will be 220.0
  75 +
  76 + # Dump some information
  77 + print("Attributes of a filled GMatrix:")
  78 + print(gammalib.parformat("Matrix fill")+str(matrix_fill))
  79 + print(gammalib.parformat("Smallest matrix element")+str(matrix_minimum))
  80 + print(gammalib.parformat("Largest matrix element")+str(matrix_maximum))
  81 + print(gammalib.parformat("Sum of all element")+str(matrix_sum))
  82 +
  83 + # Perform some matrix operations
  84 + other_matrix = matrix.copy() # Use copy() to create a deep copy
  85 + sum_matrix = matrix + other_matrix # Add two matrices
  86 + zero_matrix = matrix - other_matrix # Subtract two matrices
  87 + other_matrix += matrix # Add-on matrix
  88 + other_matrix -= matrix # Subtract off matrix
  89 + other_matrix *= 2.0 # Multiply elements by 2
  90 + other_matrix /= 2.0 # Divide elements by 2
  91 + neg_matrix = -matrix # Negate matrix
  92 + abs_matrix = gammalib.abs(neg_matrix) # Absolute value of elements
  93 +
  94 + # And now some more tricky operations
  95 + transposed = gammalib.transpose(matrix) # First transpose matrix
  96 + mult_matrix = matrix * transposed # Now we can multiply it
  97 + other_matrix *= transposed # Multiply on matrix
  98 + #inverted = gammalib.invert(matrix) # NOT YET IMPLEMENTED
  99 + vector = gammalib.GVector(5) # Allocate vector
  100 + multiplied = matrix * vector # Vector multiplication
  101 +
  102 + # Compare matrices
  103 + if matrix == abs_matrix:
  104 + print("Yes, got it!")
  105 + if matrix != transposed:
  106 + print("Got it again!")
  107 +
  108 + # Copy columns one-by-one from one matrix into another
  109 + destination = gammalib.GMatrix(4,5)
  110 + for column in range(matrix.columns()):
  111 + vector = matrix.column(column) # Extract column
  112 + destination.column(column, vector) # Set column
  113 +
  114 + # Add columns one-by-one from one matrix into another
  115 + destination = matrix.copy()
  116 + for column in range(matrix.columns()):
  117 + vector = matrix.column(column) # Extract column
  118 + destination.add_to_column(column, vector) # Add column
  119 +
  120 + # Copy rows one-by-one from one matrix into another
  121 + destination = gammalib.GMatrix(4,5)
  122 + for row in range(matrix.rows()):
  123 + vector = matrix.row(row) # Extract row
  124 + destination.row(row, vector) # Set row
  125 +
  126 + # Add rows one-by-one from one matrix into another
  127 + destination = matrix.copy()
  128 + for row in range(matrix.rows()):
  129 + vector = matrix.row(row) # Extract row
  130 + destination.add_to_row(row, vector) # Add row
  131 +
  132 + # Return
  133 + return
  134 +
  135 +
  136 +# ======================== #
  137 +# Illustrates matrix usage #
  138 +# ======================== #
  139 +def matrix_usage():
  140 + """
  141 + Illustrates the usage of the different matrix storage classes.
  142 + """
  143 + # Create matrices with 4 rows and 4 columns
  144 + matrix_generic = gammalib.GMatrix(4,4)
  145 + matrix_sparse = gammalib.GMatrixSparse(4,4)
  146 + matrix_symmetric = gammalib.GMatrixSymmetric(4,4)
  147 +
  148 + # Now set all matrix elements to specific values
  149 + for row in range(matrix_generic.rows()):
  150 + for column in range(matrix_generic.columns()):
  151 + matrix_generic[row,column] = row * column
  152 + matrix_sparse[row,column] = row * column
  153 + matrix_symmetric[row,column] = row * column
  154 +
  155 + # Convert from one storage class to another
  156 + matrix = gammalib.GMatrix(matrix_sparse)
  157 + matrix = gammalib.GMatrix(matrix_symmetric)
  158 + matrix = gammalib.GMatrixSparse(matrix_generic)
  159 + matrix = gammalib.GMatrixSparse(matrix_symmetric)
  160 + matrix = gammalib.GMatrixSymmetric(matrix_generic)
  161 + matrix = gammalib.GMatrixSymmetric(matrix_sparse)
  162 +
  163 + # Return
  164 + return
  165 +
  166 +
  167 +# ======================== #
  168 +# Main routine entry point #
  169 +# ======================== #
  170 +if __name__ == '__main__':
  171 + """
  172 + Example script for matrix handling.
  173 + """
  174 + # Dump header
  175 + print("")
  176 + print("*******************************")
  177 + print("* Example for matrix handling *")
  178 + print("*******************************")
  179 +
  180 + # Illustrate matrix handling
  181 + handle_matrix()
  182 +
  183 + # Illustrate usage of different matrix classes
  184 + matrix_usage()
  185 +
0 186 \ No newline at end of file
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