assertion error when setting ctable by index

[brentp]

here is the code to reproduce:

import bcolz
import numpy as np

dtype = np.dtype([("a", np.object),
                  ("b", np.uint8),
                  ("c", np.int32),
                  ("d", np.float32)
                  ])

a = bcolz.ctable(np.empty(2, dtype=dtype), mode="w")

val = ("asdf", 22, 3333, 33.33)
a.append(val) # ok
a[2] # ok

# error
a[0] = val

Here is the error message:

Traceback (most recent call last):
  File "t.py", line 19, in <module>
    a[0] = val
  File "/usr/local/src/gemini_install/data/anaconda/lib/python2.7/site-packages/bcolz/ctable.py", line 1155, in __setitem__
    self.cols[name][key] = value[name]
  File "bcolz/carray_ext.pyx", line 2153, in bcolz.carray_ext.carray.__setitem__ (bcolz/carray_ext.c:26591)
AssertionError

[esc]

I actually get this:

AssertionError                            Traceback (most recent call last)
<ipython-input-11-519b9005455c> in <module>()
----> 1 a[0] = val

/home/esc/gw/bcolz/bcolz/ctable.pyc in __setitem__(self, key, value)
   1153         # Then, modify the rows
   1154         for name in self.names:
-> 1155             self.cols[name][key] = value[name]
   1156         return
   1157 

/home/esc/gw/bcolz/bcolz/carray_ext.pyx in bcolz.carray_ext.carray.__setitem__ (bcolz/carray_ext.c:26488)()
   2152         print nwrow
   2153         print vlen
-> 2154         assert (nwrow == vlen)
   2155 
   2156     # This is a private function that is specific for `eval`

AssertionError: 

And in the above nwrow is 0 and vlen 1, whatever that might mean.

[esc]

Also, I tried using unpacking, but this fails:

In [21]: a[0][0], a[0][1], a[0][2], a[0][3] = val

In [22]: a
Out[22]: 
ctable((3,), [('a', 'O'), ('b', 'u1'), ('c', '<i4'), ('d', '<f4')])
  nbytes: 46; cbytes: 48.44 KB; ratio: 0.00
  cparams := cparams(clevel=5, shuffle=True, cname='blosclz')
[(None, 0, 0, 0.0) (None, 0, 0, 0.0) ('asdf', 22, 3333, 33.33000183105469)]

[esc]

There is an error with setting values by index when using a carray with a string type:

In [1]: import bcolz

In [2]: b1 = bcolz.carray([None, None, 'World'])

In [3]: b1[0]

In [4]: b1[2]
Out[4]: 'World'

In [5]: b1[0] = 'Hello'
---------------------------------------------------------------------------
AssertionError                            Traceback (most recent call last)
<ipython-input-5-14e904eeb7fe> in <module>()
----> 1 b1[0] = 'Hello'

/home/esc/gw/bcolz/bcolz/carray_ext.pyx in bcolz.carray_ext.carray.__setitem__ (bcolz/carray_ext.c:26450)()
   2150 
   2151         # Safety check
-> 2152         assert (nwrow == vlen)
   2153 
   2154     # This is a private function that is specific for `eval`

AssertionError: 

[esc]

Update, it is only a problem if you use the 'object' type.

You could use "S4" as dtype for the string column, in which case the assignment works (but the defaults values are bust)...

[esc]

Yeah, definitely object dtype issue:

In [2]: import bcolz

In [3]: b1 = bcolz.carray(['World'])

In [4]: b1
Out[4]: 
carray((1,), |S5)
  nbytes: 5; cbytes: 16.00 KB; ratio: 0.00
  cparams := cparams(clevel=5, shuffle=True, cname='blosclz')
['World']

In [5]: b1.append('Hello')

In [6]: b1
Out[6]: 
carray((2,), |S5)
  nbytes: 10; cbytes: 16.00 KB; ratio: 0.00
  cparams := cparams(clevel=5, shuffle=True, cname='blosclz')
['World' 'Hello']

In [7]: b1[0] = 'Hello'

In [8]: b1
Out[8]: 
carray((2,), |S5)
  nbytes: 10; cbytes: 16.00 KB; ratio: 0.00
  cparams := cparams(clevel=5, shuffle=True, cname='blosclz')
['Hello' 'Hello']

there is something similar going on at #182 also releated to problems with the object dtype.

[esc]

Can you submit a pull-request with a test-case that exposes the issue?