File reading examples improvements

Signed-off-by: Christopher Arndt <chris@chrisarndt.de>

beispiele/data-errors.txt

@@ -0,0 +1,5 @@
+record 1: 100, 300, 50, 200
+record 2 300, 450, 50, 100
+record 3: 150, 200, 0, 150
+record 4: 350, 200, 5O, 250
+record 5: 50, 100, 200, 300

beispiele/data.txt

@@ -0,0 +1,5 @@
+record 1: 100, 300, 50, 200
+record 2: 300, 450, 50, 100
+record 3: 150, 200, 0, 150
+record 4: 350, 200, 50, 250
+record 5: 50, 100, 200, 300

beispiele/readfile3.py

@@ -8,7 +8,7 @@ with open(filename, "r") as fileobj:
     max_linelength = 0
     longest_line = -1
 
-    for i, line in enumerate(data):
+    for i, line in enumerate(fileobj):
         if len(line) > max_linelength:
             max_linelength = len(line)
             longest_line = i + 1

beispiele/readfile4.py

@@ -2,12 +2,15 @@
 
 import sys
 
-filename = sys.argv[1]
+if len(sys.argv) >= 2:
+    filename = sys.argv[1]
+else:
+    filename = "data.txt"
 
 data = {}
 
 with open(filename, "r") as fileobj:
-    for i, line in enumerate(data):
+    for i, line in enumerate(fileobj):
         line = line.strip()  # remove whitespace from start/end of line
 
         if line.startswith('#'):

beispiele/readfile5.py

@@ -0,0 +1,29 @@
+#!/usr/bin/env python
+
+import sys
+
+if len(sys.argv) >= 2:
+    filename = sys.argv[1]
+else:
+    filename = "data.txt"
+
+data = {}
+
+try:
+    with open(filename, "r") as fileobj:
+        for i, line in enumerate(fileobj):
+            line = line.strip()  # remove whitespace from start/end of line
+
+            if line.startswith('#'):
+                # ignore comment lines
+                continue
+
+            name, raw_data = line.split(":", 1)  # split line at first colon
+            items = raw_data.split(",")          # split raw data at commas
+
+            data[name.strip()] = items
+except OSError as exc:
+    print(f"Could not open file {filename}: {exc}")
+
+for key in data:
+    print(key, data[key])

beispiele/readfile6.py

@@ -0,0 +1,36 @@
+#!/usr/bin/env python
+
+import sys
+
+if len(sys.argv) >= 2:
+    filename = sys.argv[1]
+else:
+    filename = "data.txt"
+
+data = {}
+
+try:
+    with open(filename, "r") as fileobj:
+        for i, line in enumerate(fileobj):
+            line = line.strip()  # remove whitespace from start/end of line
+
+            if line.startswith('#'):
+                # ignore comment lines
+                continue
+
+            try:
+                name, raw_data = line.split(":", 1)  # split line at first colon
+            except ValueError as exc:
+                print(f"Warning: could not parse line {i+1}: {exc}")
+            else:
+                try:
+                    items = [int(item) for item in raw_data.split(",")]          # split raw data at commas
+                except (ValueError, TypeError) as exc:
+                    print(f"Warning: could not parse data on line {i+1}: {exc}")
+
+            data[name.strip()] = items
+except OSError as exc:
+    print(f"Could not open file {filename}: {exc}")
+
+for key in data:
+    print(key, data[key])