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]
```