Source Code for Module joy.misc

 1  #  This library is free software; you can redistribute it and/or 
 2  #  modify it and use it for any purpose you wish. 
 3  # 
 4  #  The library is distributed in the hope that it will be useful, 
 5  #  but WITHOUT ANY WARRANTY; without even the implied warranty of 
 6  #  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  
 7  # 
 8  # (c) Shai Revzen, U Penn, 2010 
 9  #   
10  """ 
11  misc.py defines several useful functions that don't rightly belong in any obvious location 
12   
13  Functions 
14  --------- 
15   
16  curry -- Curry a function, returning a callable with the value of the initial parameters pre-selected. One of the mainstays of functional programming. 
17   
18  printExc -- Print a formatted stack-trace to standard error 
19   
20  loadCSV -- Load a CSV file into a list of lists 
21   
22  inlineCSV -- Similar to loadCSV, but takes the CSV text from a multiline python string 
23  """ 
24   
25  import traceback 
26  import sys 
27   
28 -def curry(fn, *cargs, **ckwargs): 
29    """ 
30    Curry a function, returning a callable with the value of the 
31    initial parameters pre-selected. For any function f 
32      curry(f,*arg0)(*arg1,**kw) f(x,*(arg0+arg1),**kw) 
33    so, for example: 
34      f(x,y) = curry(f,x)(y) = curry(f,x,y)() 
35    """ 
36    def call_fn(*fargs, **fkwargs): 
37        d = ckwargs.copy() 
38        d.update(fkwargs) 
39        return fn(*(cargs + fargs), **d) 
40    return call_fn 
41   
42 -def printExc( exinfo=None ): 
43    """ 
44    Print a formatted stack-trace to standard error  
45    """ 
46    # Print the stack trace so far to stderr 
47    if exinfo is None: 
48      exinfo = sys.exc_info() 
49    msg = ["<< "*10+"\n"] 
50    msg.extend(traceback.format_exception(*exinfo)) 
51    msg.append(">> "*10+"\n") 
52    sys.stderr.writelines(msg) 
53   
54 -def loadCSV( fn ): 
55    """ 
56    Load a CSV file into a list of lists, converting empty cells into 
57    None, numbers as floats and quoted strings as strings. 
58    
59    In addition to standard CSV format, empty (white only) lines and 
60    lines starting with "#" are ignored 
61    """ 
62    if type(fn)==str: 
63      f = open(fn,'r') 
64    else: 
65      assert iter(fn),"Must be iterable returning lines" 
66      f = fn 
67    def convert(x): 
68      x = x.strip() 
69      if not x or x=='""': return None 
70      if x[0]=='"': return x[1:-1] 
71      return float(x) 
72    res = [  
73      [ convert(x) for x in l.split(",") ]  
74      for l in f if l.strip() and l[:1]!="#" 
75    ] 
76    if type(fn)==str: 
77      f.close() 
78    return res 
79   
80 -def inlineCSV( txt ): 
81    """ 
82    Similar to loadCSV, but takes the CSV text from a multiline  
83    python string, e.g. 
84     
85    >>> sheet = inlineCSV(''' 
86    ... # Non-CSV Unix shell style comments and empty lines are ignored 
87    ... ,         "sparrow",  "banana" 
88    ... "weight", 5,          1 
89    ... ''') 
90    """ 
91    return loadCSV(( l for l in txt.split("\n") )) 
92