From 8ead922b4c6cba3b5bb68a8d0fbf38fe35d4cff9 Mon Sep 17 00:00:00 2001
From: James Turk <james.p.turk@gmail.com>
Date: Tue, 4 Nov 2008 17:20:10 +0000
Subject: [PATCH] added flatten & flattener

---
 examples/fec_cobol.py |  6 +++---
 saucebrush/filters.py | 33 +++++++++++++++++++++++++++++++++
 saucebrush/utils.py   | 22 ++++++++++++++++++++++
 3 files changed, 58 insertions(+), 3 deletions(-)

diff --git a/examples/fec_cobol.py b/examples/fec_cobol.py
index 8330909..1a2221a 100644
--- a/examples/fec_cobol.py
+++ b/examples/fec_cobol.py
@@ -45,21 +45,21 @@ def process_fec_year(year):
     source = FixedWidthFileSource(open('%s/foiacm.dta' % year), CM_FIELDS)
     #sqlite = SqliteOutput('fec%s.sqlite' % year, 'committee', [f[0] for f in CM_FIELDS if f[0] != 'filler'])
     emit_mysql = SqlDumpEmitter(open('fec%s.sql' % year,'a'), 'committee', [f[0] for f in CM_FIELDS if f[0] != 'filler'])
-    run_recipe(source, [emit_mysql])
+    run_recipe(source, emit_mysql)
 
     # candidate
     source = FixedWidthFileSource(open('%s/foiacn.dta' % year), CN_FIELDS)
     fieldremover = FieldRemover(('fillerA', 'fillerB'))
     #sqlite = SqliteOutput('fec%s.sqlite' % year, 'candidate', [f[0] for f in CN_FIELDS if f[0] != 'filler'])
     emit_mysql = SqlDumpEmitter(open('fec%s.sql' % year,'a'), 'candidate', [f[0] for f in CN_FIELDS if not f[0].startswith('filler')])
-    run_recipe(source, [fieldremover, emit_mysql])
+    run_recipe(source, fieldremover, emit_mysql)
 
     # contributions
     source = FixedWidthFileSource(open('%s/itcont.dta' % year), INDIV_FIELDS)
     decobolizer = FieldModifier(('amount', ), fix_cobol_number)
     #sqlite = SqliteOutput('fec%s.sqlite' % year, 'contribution', [f[0] for f in INDIV_FIELDS if f[0] != 'filler'])
     emit_mysql = SqlDumpEmitter(open('fec%s.sql' % year,'a'), 'contribution', [f[0] for f in INDIV_FIELDS if f[0] != 'filler'])
-    run_recipe(source, [decobolizer, emit_mysql])
+    run_recipe(source, decobolizer, emit_mysql)
 
 if __name__=='__main__':
     process_fec_year(2008)
diff --git a/saucebrush/filters.py b/saucebrush/filters.py
index f56e14a..80fd61c 100644
--- a/saucebrush/filters.py
+++ b/saucebrush/filters.py
@@ -8,6 +8,7 @@
 """
 
 from exceptions import NotImplementedError
+from saucebrush import utils
 
 ######################
 ## Abstract Filters ##
@@ -156,6 +157,9 @@ class FieldAdder(Filter):
 
         from itertools import count
         FieldAdder('id', count)
+        
+        would yield a new column named id that uses the itertools count iterable
+        to create sequentially numbered ids.
     """
 
     def __init__(self, field_name, field_value):
@@ -214,6 +218,35 @@ class Splitter(Filter):
         return record
 
 
+class Flattener(Filter):
+    """ Collapse a set of similar dictionaries into a list.
+    
+        Takes a dictionary of keys and flattens the key names:
+        
+        addresses = [{'addresses': [{'address': {'state':'NC', 'street':'146 shirley drive'}},
+                            {'address': {'state':'NY', 'street':'3000 Winton Rd'}}]}]
+        flattener = Flattener(['addresses'])
+    """
+        
+    
+    def __init__(self):
+        super(Flattener, self).__init__()
+    
+    '''def process_field(self, item):
+        # create a list of dictionaries with concatenated keys
+        retlist = []
+        for subitem in item:
+            newitem = {}
+            for key1,subdict in subitem.iteritems():
+                for key2,value in subdict.iteritems():
+                    newitem[key1+'_'+key2] = value
+            retlist.append(newitem)
+        return retlist
+    '''
+    
+    def process_record(self, record):
+        return utils.flatten(record)
+    
 
 ###########################
 ## Commonly Used Filters ##
diff --git a/saucebrush/utils.py b/saucebrush/utils.py
index c8140ac..42974f7 100644
--- a/saucebrush/utils.py
+++ b/saucebrush/utils.py
@@ -32,6 +32,28 @@ def string_dig(element, joiner=''):
         return joiner.join([string_dig(child) for child in element.findAll(True)])
 
 
+def flatten(item, prefix=''):
+    """
+        Flatten nested dictionary into one with its keys concatenated together.
+        
+        >>> flatten({'a':1, 'b':{'c':2}, 'd':[{'e':{'r':7}}, {'e':5}],
+                    'f':{'g':{'h':6}}})
+        {'a': 1, 'b_c': 2, 'd': [{'e_r': 7}, {'e': 5}], 'f_g_h': 6}
+    """
+    if isinstance(item, dict):
+        # don't prepend a leading _
+        if prefix != '':
+            prefix += '_'
+        retval = {}
+        for key, value in item.iteritems():
+            retval.update(flatten(value, prefix + key))
+        return retval
+    elif isinstance(item, (tuple, list)):
+        return {prefix: [flatten(i) for i in item]}
+    else:
+        return {prefix: item}
+
+
 def dotted_key_lookup(dict_, dotted_key, default=KeyError, separator='.'):
     """
         Do a lookup within dict_ by the various elements of dotted_key.