From a6dd93fdac084eed879b9803b50552ff6ec09da1 Mon Sep 17 00:00:00 2001
From: Jürgen Knödlseder <jurgen.knodlseder@irap.omp.eu>
Date: Tue, 19 Nov 2013 15:50:50 +0100
Subject: [PATCH] Add PHA spectrum display script.

---
 examples/show_pha.py | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+), 0 deletions(-)
 create mode 100755 examples/show_pha.py

diff --git a/examples/show_pha.py b/examples/show_pha.py
new file mode 100755
index 0000000..a8b358e
--- /dev/null
+++ b/examples/show_pha.py
@@ -0,0 +1,110 @@
+#! /usr/bin/env python
+# ==========================================================================
+# This script displays a spectrum in PHA format.
+#
+# Required 3rd party modules:
+# - matplotlib
+# - numpy
+#
+# Copyright (C) 2013 Juergen Knoedlseder
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# ==========================================================================
+import sys
+import math
+from gammalib import *
+
+
+# ================= #
+# Show PHA spectrum #
+# ================= #
+def show_pha(pha):
+    """
+    """
+    # Create figure
+    plt.figure(1)
+    plt.title("PHA spectrum (" + pha.filename() + ")")
+
+    # Generate energy vector
+    energy   = []
+    channels = False
+    if pha.ebounds().size() > 0:
+        for i in range(pha.ebounds().size()):
+            energy.append(pha.ebounds().elogmean(i).TeV())
+    else:
+        for i in range(pha.size()):
+            energy.append(float(i+1))
+            channels = True
+
+    # Generate data and error vector
+    counts = [0.0 for i in range(pha.size())]
+    for i in range(pha.size()):
+        counts[i] = pha[i]
+    error = [math.sqrt(c) for c in counts]
+    
+    # Plot data
+    if channels:
+        plt.semilogy(energy, counts, 'ro')
+    else:
+        plt.loglog(energy, counts, 'ro')
+    plt.errorbar(energy, counts, error, fmt=None, ecolor='r')
+
+    # Set axes
+    if channels:
+        plt.xlabel("Channels")
+    else:
+        plt.xlabel("Energy (TeV)")
+    plt.ylabel("Counts")
+
+    # Show plot
+    plt.show()
+    
+    # Return
+    #return
+    
+    
+# ======================== #
+# Main routine entry point #
+# ======================== #
+if __name__ == '__main__':
+    """
+    Display spectrum in PHA format.
+    """
+    # Print usage information
+    usage = "Usage: show_pha filename" \
+            " [-n bins] [-c column] [-t title] [-p plot]"
+    if len(sys.argv) < 2:
+        print(usage)
+        sys.exit()
+
+    # Extract parameters
+    filename = sys.argv[1]
+
+    # Load PHA spectrum
+    pha = GPha(filename)
+    #print(pha)
+
+    # Try importing matplotlib
+    try:
+        import matplotlib.pyplot as plt
+        has_matplotlib = True
+    except ImportError:
+        print("Matplotlib is not (correctly) installed on your system.")
+        has_matplotlib = False
+
+    # Show PHA spectrum
+    if has_matplotlib:
+        show_pha(pha)
+    
\ No newline at end of file
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