I'm unable to make the following code work, though I don't see this error working strictly in R.

```
from rpy2.robjects.packages import importr
from rpy2 import robjects
import numpy as np

forecast = importr('forecast')
ts = robjects.r['ts']

y = np.random.randn(50)
X = np.random.randn(50)

y = ts(robjects.FloatVector(y), start=robjects.IntVector((2004, 1)), frequency=12)
X = ts(robjects.FloatVector(X), start=robjects.IntVector((2004, 1)), frequency=12)

forecast.Arima(y, xreg=X, order=robjects.IntVector((1, 0, 0)))

```

It's especially confusing considering the following code works fine

```
forecast.auto_arima(y, xreg=X)

```

I see the following traceback no matter what I give for X, using numpy interface or not. Any ideas?

```
---------------------------------------------------------------------------
RRuntimeError                             Traceback (most recent call last)
<ipython-input-20-b781220efb93> in <module>()
     13 X = ts(robjects.FloatVector(X), start=robjects.IntVector((2004, 1)),  frequency=12)
     14 
---> 15 forecast.Arima(y, xreg=X, order=robjects.IntVector((1, 0, 0)))

/home/skipper/.local/lib/python2.7/site-packages/rpy2/robjects/functions.pyc in     __call__(self, *args, **kwargs)
    84                 v = kwargs.pop(k)
    85                 kwargs[r_k] = v
---> 86         return super(SignatureTranslatedFunction, self).__call__(*args, **kwargs)

/home/skipper/.local/lib/python2.7/site-packages/rpy2/robjects/functions.pyc in __call__(self, *args, **kwargs)
    33         for k, v in kwargs.iteritems():
    34             new_kwargs[k] = conversion.py2ri(v)
---> 35         res = super(Function, self).__call__(*new_args, **new_kwargs)
    36         res = conversion.ri2py(res)
    37         return res

RRuntimeError: Error in `colnames<-`(`*tmp*`, value = if (ncol(xreg) == 1) nmxreg else    paste(nmxreg,  : 
length of 'dimnames' [2] not equal to array extent

```

**Edit**:

The problem is that the following lines of code do not evaluate to a column name, which seems to be the expectation on the R side.

```
sub = robjects.r['substitute']
deparse = robjects.r['deparse']
deparse(sub(X))

```

I don't know well enough what the expectations of this code should be in R, but I can't find an RPy2 object that passes this check by returning something of `length == 1`. This really looks like a bug to me.

```
R> length(deparse(substitute((rep(.2, 1000)))))
[1] 1

```

But in Rpy2

```
[~/]
[94]: robjects.r.length(robjects.r.deparse(robjects.r.substitute(robjects.r('rep(.2,     1000)'))))
[94]: 
<IntVector - Python:0x7ce1560 / R:0x80adc28>
[      78]

```