R passing data frame to another program using system()

Question

I have a data frame that I pass to another program using system(). In the current setup, I first write the contents of the dataframe to a text file, then have the system() command look for the created text file.

df1 <- runif(20)
write(df1, file="file1.txt")
system("myprogram file1.txt")

I have 2 questions:

1) Is there a way to pass a dataframe directly without writing the text file?

2) If not, is there are way to pass the data in memory as a text formatted entity without writing the file to disk?

Thanks for any suggestions.

How long is a typical data frame? One option would be to pass the data as parameters to the command, but I think what you've already done is probably cleaner. — Jesse Anderson
– Jesse Anderson, Commented Aug 15, 2012 at 15:49

Dirk is no longer here · Accepted Answer · 2012-08-15 15:55:17Z

8

You can write to anything R calls connections, and that includes network sockets.

So process A can write to the network, and process B can read it without any file-on-disk involved, see help(connections) which even has a working example in the "Examples" section.

Your general topic here is serialization, and R does that for you. You can also pass data that way to other programs using tools that encode metadata about your data structure -- as for example Google's Protocol Buffers (supported in R by the RProtoBuf package).

answered Aug 15, 2012 at 15:55

Dirk is no longer here

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user3735877 · Accepted Answer · 2022-10-21 21:17:41Z

0

I spent quite a while and couldn't understand the accepted answer. But I figured out a workaround.

df1 <- runif(20)
system("myprogram /dev/stdin", input = write.table(df1))

However, according to documentation, the input argument will actually be redirected to a temp file, which I suppose will involve some i/o.

answered Oct 21, 2022 at 21:17

user3735877

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