"Error while parsing the string" when using RPy2 and dplyr

Question

I'm using R to do some data manipulation. This is a part of a larger project that is mostly in Python, so I'm not using R directly but RPy2 instead. Things work fine until I get to the dplyr part.

This works:

from rpy2.robjects import r

Rcode = '''library(RODBC)
library(dplyr)
# ...
# a bunch of R code that fetches data from SQL Server
# ...'''.format(db_name = 'foo')
print r(Rcode)

That gives me the data I want.

But when I try to do some data manipulation with dplyr, like this:

from rpy2.robjects import r

Rcode = '''library(RODBC)
library(dplyr)
# ...
# a bunch of R code that fetches data from SQL Server
# ...
myData <- myData
    %>% group_by(someDataField)'''.format(db_name = 'foo')
print r(Rcode)

I get an error:

Traceback (most recent call last):
  File "myScript.py", line 53, in <module>
    print r(Rcode)
  File "C:\Python27\lib\site-packages\rpy2\robjects\__init__.py", line 268, in __call__
    p = rinterface.parse(string)
ValueError: Error while parsing the string.

I've tried escaping the % signs, escaping the > sign, and putting them within quotation marks, but nothing worked.

What am I missing?

I've seen the other questions about the same error (like here and here) but they didn't help.

I'm using Python 2.7.10 and RPy2 2.5.6.

Yes - sorry, just fixed it (this is a simplification of the actual code and I mistyped here). — Parzival
– Parzival, Commented Jul 6, 2015 at 19:23
did you try to do something like : myData <- group_by(MyData,someDataField), just to see if the error is really in the %>% function ? — Andrelrms
– Andrelrms, Commented Jul 6, 2015 at 19:31
That did it. Thanks! You should probably make it an answer so I can accept it. — Parzival
– Parzival, Commented Jul 6, 2015 at 19:35

Andrelrms · Accepted Answer · 2015-07-06 19:36:26Z

1

myData <- group_by(MyData,someDataField)

answered Jul 6, 2015 at 19:36

Andrelrms

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1 Comment

Comm4nd0 Over a year ago

this explains nothing

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