如何将 R 的 .rdata 文件加载到 Python 中？

Question

I am trying to convert one part of R code in to Python. In this process I am facing some problems.

I have a R code as shown below. Here I am saving my R output in .rdata format.

nms <- names(mtcars)
save(nms,file="mtcars_nms.rdata")

Now I have to load the mtcars_nms.rdata into Python. I imported rpy2 module. Then I tried to load the file into python workspace. But could not able to see the actual output.

I used the following python code to import the .rdata .

import pandas as pd
from rpy2.robjects import r,pandas2ri
pandas2ri.activate()

robj = r.load('mtcars_nms.rdata')
robj

My python output is

R object with classes: ('character',) mapped to:
<StrVector - Python:0x000001A5B9E5A288 / R:0x000001A5B9E91678>
['mtcars_nms']

Now my objective is to extract the information from mtcars_nms.

In R, we can do this by using

load("mtcars_nms.rdata");
get('mtcars_nms')

Now I wanted to do the same thing in Python.

Answer 1

There is a new python package pyreadr that makes very easy import RData and Rds files into python:

import pyreadr

result = pyreadr.read_r('mtcars_nms.rdata')

mtcars = result['mtcars_nms']

It does not depend on having R or other external dependencies installed. It is a wrapper around the C library librdata , therefore it is very fast.

You can install it very easily with pip:

pip install pyreadr

The repo is here: https://github.com/ofajardo/pyreadr

Disclaimer: I am the developer.

Answer 2

Rather than using the .rdata format, I would recommend to use feather , which allows to efficiently share data between R and Python.

In R, you would run something like this:

library(feather)
write_feather(nms, "mtcars_nms.feather")

In Python, to load the data into a pandas dataframe, you can then simply run:

import pandas as pd
nms = pd.read_feather("mtcars_nms.feather")

Answer 3

The R function load will return an R vector of names for the objects that were loaded (into GlobalEnv).

You'll have to do in rpy2 pretty much what you are doing in R:

R:

get('mtcars_nms')

Python/rpy2

robjects.globalenv['mtcars_nms']