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--- misc:code_snippets:python [2016/09/29 16:30] – extended colored output example, print_error included sascha
+++ misc:code_snippets:python [2017/04/11 15:13] (current) – Fix sascha
@@ Line 21: / Line 21: @@
             raise e
         sys.exit(1)
+</code>
+==== Liste zeilenweise ausgeben ====
+<code python>
+print(*myList, sep='\n')
+</code>
+==== Erstes Listenelement oder None erhalten ====
+<code python>
+next(iter(your_list or []), None)
 </code>
@@ Line 48: / Line 62: @@
 else:
     print('The for loop is over.')
+</code>
+==== Temporäres Verzeichnis als Context Manager verwenden ====
+<code python>
+import tempfile
+with tempfile.TemporaryDirectory() as tmp_dir:
+    pass  # do stuff
+</code>
+==== Mittels Pipe übergebene Daten lesen ====
+<code python>
+import sys
+# ensure the script only reads piped data and doesn't wait for user input
+if not sys.stdin.isatty():
+    lst = [l.strip() for l in sys.stdin.readlines() if not l.startswith('#')]
+    print(lst)
+</code>
+==== Dateien aus einem Verzeichnis erhalten oder aus Datei lesen ====
+<code python>
+import os
+from os.path import expanduser, isdir, isfile, abspath, join as pjoin
+def get_files(path=/some/path):
+    files = []
+    path = expanduser(path)
+    if isdir(path):
+        files = [pjoin(abspath(path), f) for f in os.listdir(path) if
+                 (isfile(pjoin(path, f)) and f.lower().endswith('.ext'))]
+    elif isfile(path):
+        with open(path, 'r') as lst:
+            files = [l.strip() for l in lst.readlines() if not l.startswith('#') and l.split()]
+    return files
+</code>
+==== Anführungszeichen um einen String entfernen ====
+<code python>
+def unquote(string):
+    """Remove matching pair of single or double quotes around string"""
+    if (string[0] == string[-1]) and string.startswith(("'", '"')):
+        return string[1:-1]
+    return string
+</code>
+Ohne Überprüfen von passenden Angührungszeichen:
+<code python>
+return re.sub(r'^["\']|["\']$', '', string)
 </code>
@@ Line 200: / Line 274: @@
 progress_simple(total)
 progress(total, 40, '#', '-')
+</code>
+==== Verzeichnis temporär wechseln (Exception-safe) ====
+<code python cd_exception_safe.py>
+from contextlib import contextmanager
+import os
+@contextmanager
+def cd(newdir):
+    prevdir = os.getcwd()
+    os.chdir(os.path.expanduser(newdir))
+    try:
+        yield
+    finally:
+        os.chdir(prevdir)
+# cd using context manager and decorator
+# directory is reverted even after an exception is thrown
+os.chdir('/home')
+with cd('/tmp'):
+    # ...
+    raise Exception("There's no place like home.")
+# Directory is now back to '/home'.
+</code>
+==== Liste mit Inhalt einer anderen Liste filtern ====
+<code python>
+# filter a list by checking if substring of another list is contained in entries of the list to be filtered
+# here flags is some list which contain entries from the list regex --> filter matching regex from list flags
+flags = ['"s/regex/looking/g"', 'options', '"s/another/regex/"', '--more flags']
+regex = [unquote(flag) for flag in flags if unquote(flag).startswith('s/')]
+flags = [flag for flag in flags if not any(flag for reg in regex if reg in flag)]
 </code>