Differences

This shows you the differences between two versions of the page.

--- python:index [2012/08/29 08:39] – tkbletsc
+++ python:index [2024/07/09 07:28] (current) – tkbletsc
@@ Line 1: / Line 1: @@
 ====== Python ======
-  * [[Colorization and tab completion for the python shell]]
+  * [[:Python virtual environment recipe|]]
-  * [[Defer to another program in the PATH, if available]]
+  * [[:python:colorization_and_tab_completion_for_the_python_shell|Colorization and tab completion for the python shell]]
-  * [[SOCKSv4 proxy]] - Simple proxy in pure python.
+  * [[:python:defer_to_another_program_in_the_path_if_available|Defer to another program in the PATH, if available]]
-  * [[virtualenv]] - A recipe to download and deploy Python 2.7 in your home directory without dependencies (except gcc)
+  * [[:python:socksv4_proxy|SOCKSv4 proxy]] - Simple proxy in pure python.
-  * [[optparse]]
+  * [[:python:virtualenv|]] - A recipe to download and deploy Python 2.7 in your home directory without dependencies (except gcc)
-  * [[IntVectorRange]]
+  * [[:python:optparse|]]
-  * [[Progress bar]]
+  * [[:python:intvectorrange|IntVectorRange]]
-  * [[Simple DynDNS updater]]
+  * [[:python:progress_bar|Progress bar]]
+  * [[:python:simple_dyndns_updater|Simple DynDNS updater]]
+<code python>
+# use this like a dictonary (d['thing']) OR an object (d.thing)
+class DictObject(dict):
+    def __getattribute__(self,k): return self[k]
+    def __setattribute__(self,k,v): self[k]=v
+from datetime import datetime
+def timestamp(): return datetime.now().strftime("%Y%m%d-%H%M%S")
+def avg(v): return sum(v)/len(v)
+def stdev(v): return math.sqrt(sum(x*x for x in v) / len(v) - (avg(v) ** 2))
+def pct_diff(a,b): return (a/b)-1
+def product(L): return reduce(lambda x,y: x*y, L, 1)
+def ping(host,timeout=1):
+    ret = subprocess.call(['ping','-c1','-W',str(timeout),host],stdout=open('/dev/null', 'w'))
+    return ret==0
-<code=python>
 from timeit import Timer
 t = Timer("test()", "from __main__ import test")
@@ Line 16: / Line 34: @@
 def shred_unicode(s):
-	return unicodedata.normalize('NFKD', s.decode("utf-8")).encode('ascii','ignore')
+    return unicodedata.normalize('NFKD', s.decode("utf-8")).encode('ascii','ignore')
+# divide a list into equal pieces.
+# chunk ranges from 0 to num_chunks-1
+def divide_list(lst,chunk,num_chunks):
+    i = int( float(chunk)/num_chunks*len(lst) )
+    j = int( float(chunk+1)/num_chunks*len(lst) )-1
+    return lst[i:j]
 import itertools
 def sliding_window(seq, n=2, pad_value=None, pad_left=0, pad_right=0):
-	"Returns a sliding window (of width n) over data from the iterable."
+    "Returns a sliding window (of width n) over data from the iterable."
-	"Can optionally pad the window left and right."
+    "Can optionally pad the window left and right."
-	it = itertools.chain(
+    it = itertools.chain(
-		itertools.repeat(pad_value,pad_left),
+        itertools.repeat(pad_value,pad_left),
-		seq,
+        seq,
-		itertools.repeat(pad_value,pad_right),
+        itertools.repeat(pad_value,pad_right),
-	)
+    )
-	#it = iter(seq)
+    #it = iter(seq)
-	result = tuple(itertools.islice(it, n))
+    result = tuple(itertools.islice(it, n))
-	if len(result) == n:
+    if len(result) == n:
-		yield result
+        yield result
-	for elem in it:
+    for elem in it:
-		result = result[1:] + (elem,)
+        result = result[1:] + (elem,)
-		yield result
+        yield result
 def open_dash(filename,mode='r',bufsize=-1):
-	if filename == '-':
+    if filename == '-':
-		if 'w' in mode  or  'a' in mode: return sys.stdout
+        if 'w' in mode  or  'a' in mode: return sys.stdout
-		elif 'r' in mode:                return sys.stdin
+        elif 'r' in mode:                return sys.stdin
-		else:                            raise Exception("Bad mode")
+        else:                            raise Exception("Bad mode")
-	else:
+    else:
-		return open(filename,mode,bufsize)
+        return open(filename,mode,bufsize)
 # allows you to put color codes in backticks and have them turned into escape codes
@@ Line 51: / Line 76: @@
 heuristics = {}
 def heuristic(func):
-	name = func.__name__.replace('gadget_is_','').replace('gadget_','').replace('_','-')
+    name = func.__name__.replace('gadget_is_','').replace('gadget_','').replace('_','-')
-	heuristics[name]=func
+    heuristics[name]=func
-	return func
+    return func
-def uniq(seq, idfun=None):
+# unlike set(), this is order preserving
-    # order preserving
+def uniq(seq, idfunc=None):
-    if idfun is None: idfun = lambda x: x
+    seen = set()
-    seen = {}
-    result = []
     for item in seq:
-        marker = idfun(item)
+        marker = idfunc(item) if idfunc else item
         if marker not in seen:
-			seen[marker] = 1
+            seen.add(marker)
-			result.append(item)
+            yield item
-    return result
-def product(L): return reduce(lambda x,y: x*y, L, 1)
 </code>
+Drop into python shell:
+<code python>
+import code
+code.interact(local=locals())
+</code>
+<code python>
+class ConsoleThrobber(object):
+    def __init__(self,chars='/\\'):
+        self.chars=chars
+        self.i=0
+    def __call__(self):
+        sys.stdout.write("\r" + self.chars[self.i])
+        sys.stdout.flush()
+        self.i = (self.i + 1) % len(self.chars)
+def workload():
+    throb = ConsoleThrobber("\\|/-")
+    while True:
+        # ... do stuff ...
+        throb()
+def recognize_type(v):
+    if re.match(r'\d+$',v):
+        return int(v)
+    if re.match(r'\d+\.\d*$',v):
+        return float(v)
+    return v
+</code>
+Parse tab-delimited tables, especially pasted from excel:
+<code python>
+def recognize_type(v):
+    try: return float(v)
+    except ValueError: pass
+    try: return int(v)
+    except ValueError: pass
+    return v
+def parse_table(table_tsv, xform=recognize_type):
+    table_rows = table_tsv.strip().split("\n")
+    table = {}
+    col_headers = table_rows[0].split("\t")[1:]
+    row_headers = [x.split("\t")[0] for x in table_rows[1:]]
+    for row_header,row in zip(row_headers,table_rows[1:]):
+        values = row.split("\t")[1:]
+        table[row_header] = { 'name' : row_header }
+        for (col_header,value) in zip(col_headers,values):
+            if xform: value = xform(value)
+            table[row_header][col_header] = value
+    return (row_headers,col_headers,table)
+engines_tsv = """name    cost    mass    thrust    TWR    Isp_atm    Isp_vac
+LV-1R Liquid Fuel Engine    650    0.03    4    13.6    220    290
+O-10 MonoPropellant Engine    800    0.09    20    22.7    220    290
+Rockomax 24-77    480    0.09    20    22.7    250    300
+Rockomax Mark 55 Radial Mount Liquid Engine    850    0.9    120    13.6    290    320
+LV-1 Liquid Fuel Engine    350    0.03    4    13.6    220    290
+Rockomax 48-7S    300    0.1    30    30.6    300    350
+LV-T30 Liquid Fuel Engine    850    1.25    215    17.5    320    370
+LV-T45 Liquid Fuel Engine    950    1.5    200    13.6    320    370
+LV-909 Liquid Fuel Engine    750    0.5    50    10.2    300    390
+R.A.P.I.E.R. Engine    3600    1.75    175    10.2    320    360
+Toroidal Aerospike Rocket    3850    1.5    175    11.9    388    390
+Rockomax "Poodle" Liquid Engine    1600    2    220    11.2    270    390
+Rockomax "Mainsail" Liquid Engine    5650    6    1500    25.5    320    360
+Rockomax "Skipper" Liquid Engine    2850    3    650    22.1    320    370
+LV-N Atomic Rocket Motor    8700    2.25    60    2.7    220    800
+LFB KR-1x2    16400    10    2000    20.4    320    360
+Kerbodyne KR-2L Advanced Engine    20850    6.5    2500    39.2    320    380
+S3 KS-25x4 Engine Cluster    32400    9.75    3200    33.5    320    360
+"""
+(engine_names,fields,engines) = parse_table(engines_tsv, recognize_type)
+</code>