我想估计模型
fit <- nlme::lme(y ~ T + t, random = ~ 1 | sub, correlation = corAR1( form = ~ 1 | sub))
在rpy2中。我正在毫无问题地运行以下内容：
formula = robjects.Formula('y0 ~ T + t + c0')
random = robjects.Formula('~1|sub')
m1 = nlme.lme(formula,random=random, data=endogexog)
其中endogexog是我的对应数据。
然而，当我想通过correlation参数指定subject中错误的ar1结构时，我会得到一个错误。
correlation_formula = robjects.Formula("~ 1|sub")
m2 = nlme.lme(formula,random=random, correlation=nlme.corAR1(form=correlation_formula), data=endogexog)
WARNING:rpy2.rinterface_lib.callbacks:R[write to console]: Error in formula.default(object) : invalid formula
---------------------------------------------------------------------------
RRuntimeError Traceback (most recent call last)
<ipython-input-26-3653905f35ef> in <module>
3 # The general idea is right, see https://stackoverflow.com/questions/17333351/correlation-structure-corar1-not-defined-in-rpy2-generalised-least-squares-m
4 # how to pass it correctly with correlation argument specified?
----> 5 m2 = nlme.lme(formula,random=random, correlation=nlme.corAR1(form=correlation_formula), data=endogexog)
3 frames
/usr/local/lib/python3.7/dist-packages/rpy2/rinterface.py in __call__(self, *args, **kwargs)
678 )
679 if error_occured[0]:
--> 680 raise embedded.RRuntimeError(_rinterface._geterrmessage())
681 return res
682
RRuntimeError: Error in formula.default(object) : invalid formula
知道为什么会这样吗？
尝试使用stats.asOneSidedFormula
from rpy2.robjects.packages import importr
stats = importr('stats')
# correlation_formula = robjects.Formula("~ 1|sub")
correlation_formula = stats.asOneSidedFormula("~ 1|sub")