From 489678e3218e82409ab07509a2c41b90e09fb764 Mon Sep 17 00:00:00 2001
From: Cees Bassa <cbassa@gmail.com>
Date: Sat, 18 Jun 2022 18:01:38 +0200
Subject: [PATCH] Nicer plotting, proper use of datetime

---
 rfplot.py     | 25 ++++++++++++++++++++++---
 strf/rfio.py  | 20 +++++++++++---------
 strf/rfio.py~ | 37 -------------------------------------
 3 files changed, 33 insertions(+), 49 deletions(-)
 delete mode 100644 strf/rfio.py~

diff --git a/rfplot.py b/rfplot.py
index 2940c54..e7630e7 100644
--- a/rfplot.py
+++ b/rfplot.py
@@ -3,6 +3,8 @@ import numpy as np
 from strf.rfio import Spectrogram
 
 import matplotlib.pyplot as plt
+import matplotlib.dates as mdates
+
 
 if __name__ == "__main__":
     # Settings
@@ -17,8 +19,25 @@ if __name__ == "__main__":
     # Create plot
     vmin, vmax = np.percentile(s.z, (5, 99.95))
 
-    fig, ax = plt.subplots()
-    ax.imshow(s.z, origin="lower", aspect="auto", interpolation="None",
-              vmin=vmin, vmax=vmax)
+    # Time limits
+    tmin, tmax = mdates.date2num(s.t[0]), mdates.date2num(s.t[-1])
 
+    # Frequency limits
+    fcen = np.mean(s.freq)
+    fmin, fmax = (s.freq[0] - fcen) * 1e-6, (s.freq[-1] - fcen) * 1e-6
+    
+    fig, ax = plt.subplots(figsize=(10, 6))
+    ax.imshow(s.z, origin="lower", aspect="auto", interpolation="None",
+              vmin=vmin, vmax=vmax,
+              extent=[tmin, tmax, fmin, fmax])
+
+    ax.xaxis_date()
+    date_format = mdates.DateFormatter("%F\n%H:%M:%S")
+    ax.xaxis.set_major_formatter(date_format)
+    fig.autofmt_xdate(rotation=0, ha="center")
+
+    ax.set_xlabel("Time (UTC)")
+    ax.set_ylabel(f"Frequency (MHz) - {fcen * 1e-6:g} MHz")
+
+    
     plt.show()
diff --git a/strf/rfio.py b/strf/rfio.py
index c8be4cc..aff1aca 100644
--- a/strf/rfio.py
+++ b/strf/rfio.py
@@ -2,10 +2,10 @@
 import os
 import re
 
-from datetime import datetime
-
 import numpy as np
 
+from datetime import datetime, timedelta
+
 class Spectrogram:
     """Spectrogram class"""
 
@@ -13,32 +13,34 @@ class Spectrogram:
         """Define a spectrogram"""
 
         # Read first file to get number of channels
-        fname = os.path.join(path, "{:s}_{:06d}.bin".format(prefix, ifile))
+        fname = os.path.join(path, f"{prefix}_{ifile:06d}.bin")
         with open(fname, "rb") as fp:
             header = parse_header(fp.read(256))
 
         # Set frequencies
-        freq = np.linspace(-0.5*header["bw"], 0.5*header["bw"], header["nchan"], endpoint=False)+header["freq"]+0.5*header["bw"]/header["nchan"]
+        freq_cen, bw, nchan = header["freq"], header["bw"], header["nchan"]
+        freq_min, freq_max = -0.5 * bw, 0.5 * bw
+        freq = freq_cen + np.linspace(freq_min, freq_max, nchan, endpoint=False) + freq_max / nchan
         
         # Loop over subints and files
         zs = []
-        mjds = []
+        t = []
         isub = 0;
         while isub<nsub:
             # File name of file
-            fname = os.path.join(path, "{:s}_{:06d}.bin".format(prefix, ifile))
+            fname = os.path.join(path, f"{prefix}_{ifile:06d}.bin")
             with open(fname, "rb") as fp:
                 next_header = fp.read(256)
                 while next_header:
                     header = parse_header(next_header)
-#                    mjds.append(Time(header["utc_start"], format="datetime", scale="utc").mjd+0.5*header["length"]/86400.0)
-                    zs.append(np.fromfile(fp, dtype=np.float32, count=header["nchan"]))
+                    t.append(header["utc_start"] + timedelta(seconds=0.5 * header["length"]))
+                    zs.append(np.fromfile(fp, dtype=np.float32, count=nchan))
                     next_header = fp.read(256)
                     isub += 1
             ifile += 1
 
         self.z = np.transpose(np.vstack(zs))
-        self.mjd = np.array(mjds)
+        self.t = t
         self.freq = freq
         self.siteid = siteid
         self.nchan = self.z.shape[0]
diff --git a/strf/rfio.py~ b/strf/rfio.py~
deleted file mode 100644
index 992f28f..0000000
--- a/strf/rfio.py~
+++ /dev/null
@@ -1,37 +0,0 @@
-class Spectrogram:
-    """Spectrogram class"""
-
-    def __init__(self, path, prefix, ifile, nsub, siteid):
-        """Define a spectrogram"""
-
-        # Read first file to get number of channels
-        fname = os.path.join(path, "{:s}_{:06d}.bin".format(prefix, ifile))
-        with open(fname, "rb") as fp:
-            header = parse_header(fp.read(256))
-
-        # Set frequencies
-        freq = np.linspace(-0.5*header["bw"], 0.5*header["bw"], header["nchan"], endpoint=False)+header["freq"]+0.5*header["bw"]/header["nchan"]
-        
-        # Loop over subints and files
-        zs = []
-        mjds = []
-        isub = 0;
-        while isub<nsub:
-            # File name of file
-            fname = os.path.join(path, "{:s}_{:06d}.bin".format(prefix, ifile))
-            with open(fname, "rb") as fp:
-                next_header = fp.read(256)
-                while next_header:
-                    header = parse_header(next_header)
-                    mjds.append(Time(header["utc_start"], format="datetime", scale="utc").mjd+0.5*header["length"]/86400.0)
-                    zs.append(np.fromfile(fp, dtype=np.float32, count=header["nchan"]))
-                    next_header = fp.read(256)
-                    isub += 1
-            ifile += 1
-
-        self.z = np.transpose(np.vstack(zs))
-        self.mjd = np.array(mjds)
-        self.freq = freq
-        self.siteid = siteid
-        self.nchan = self.z.shape[0]
-        self.nsub = self.z.shape[1]