Revision: 7746
http://matplotlib.svn.sourceforge.net/matplotlib/?rev=7746&view=rev
Author: sameerd
Date: 2009-09-11 20:58:27 +0000 (Fri, 11 Sep 2009)
Log Message:
-----------
Added a recs_join function to join a single column of multiple record arrays
Modified Paths:
--------------
trunk/matplotlib/lib/matplotlib/cbook.py
trunk/matplotlib/lib/matplotlib/mlab.py
Modified: trunk/matplotlib/lib/matplotlib/cbook.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/cbook.py 2009-09-11 20:48:10 UTC (rev
7745)
+++ trunk/matplotlib/lib/matplotlib/cbook.py 2009-09-11 20:58:27 UTC (rev
7746)
@@ -1626,7 +1626,48 @@
import matplotlib.mlab as mlab
return mlab.quad2cubic(q0x, q0y, q1x, q1y, q2x, q2y)
+def align_iterators(func, *iterables):
+ """
+ This generator takes a bunch of iterables that are ordered by func
+ It sends out ordered tuples (func(row), [rows from all iterators
matching func(row)])
+
+ It is used by mlab.recs_join to join record arrays
+ """
+ class myiter:
+ def __init__(self, it):
+ self.it = it
+ self.key = self.value = None
+ self.iternext()
+ def iternext(self):
+ try:
+ self.value = self.it.next()
+ self.key = func(self.value)
+ except StopIteration:
+ self.value = self.key = None
+
+ def __call__(self, key):
+ retval = None
+ if key == self.key:
+ retval = self.value
+ self.iternext()
+ elif self.key and key > self.key:
+ raise ValueError, "Iterator has been left behind"
+ return retval
+
+ # This can be made more efficient by not computing the minimum key for
each iteration
+ iters = [myiter(it) for it in iterables]
+ minvals = minkey = True
+ while 1:
+ minvals = (filter(None, [it.key for it in iters]))
+ if minvals:
+ minkey = min(minvals)
+ yield (minkey, [it(minkey) for it in iters])
+ else:
+ break
+
+
+
if __name__=='__main__':
assert( allequal([1,1,1]) )
assert(not allequal([1,1,0]) )
Modified: trunk/matplotlib/lib/matplotlib/mlab.py
===================================================================
--- trunk/matplotlib/lib/matplotlib/mlab.py 2009-09-11 20:48:10 UTC (rev
7745)
+++ trunk/matplotlib/lib/matplotlib/mlab.py 2009-09-11 20:58:27 UTC (rev
7746)
@@ -91,6 +91,9 @@
:meth:`rec_join`
join two record arrays on sequence of fields
+:meth:`recs_join`
+ a simple join of multiple recarrays using a single column as a key
+
:meth:`rec_groupby`
summarize data by groups (similar to SQL GROUP BY)
@@ -139,7 +142,7 @@
"""
from __future__ import division
-import csv, warnings, copy, os
+import csv, warnings, copy, os, operator
import numpy as np
ma = np.ma
@@ -1880,7 +1883,29 @@
return newrec
+def recs_join(key, name, recs,missing=0.):
+ """
+ *key* is the column name that acts as a key
+ *name* is the name that we want to join
+ *missing" is what the missing fields are replaced by
+ *recarrays* is a list of record arrays to join
+ returns a record array with columns [rowkey, name1, name2, ... namen]
+
+ >>> r = recs_join("date", "close", recs=[r0, r1], missing=0.)
+
+ """
+ results = []
+ def extract(r):
+ if r is None: return missing
+ else: return r[name]
+
+ for rowkey, row in cbook.align_iterators(operator.attrgetter(key),
*[iter(r) for r in recs]):
+ results.append([rowkey] + map(extract, row))
+ names = ",".join([key] + ["%s%d" % (name, d) for d in range(len(recs))])
+ return np.rec.fromrecords(results, names=names)
+
+
def csv2rec(fname, comments='#', skiprows=0, checkrows=0, delimiter=',',
converterd=None, names=None, missing='', missingd=None,
use_mrecords=False):
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