How to use R's sprintf to create fixed width strings with fill whitespace at the END?

Question

I have vector of strings and want to create a fixed with string out of that. Shorter strings should be filled up with white spaces. E.g.:

c("fjdlksa01dada","rau","sjklf")
sprintf("%8s")
# returns
[1] "fjdlksa01dada" "     rau"      "   sjklf"

But how can I get the additional whitespace at the END of the string?

Note that I heard of write.fwf from the gdata package which is really nice but doesn't help much in this case, because I need to write a very specific non-standard format for an outdated old program.

score 25 · Accepted Answer · answered Feb 13 '12 at 14:16

25

Add a minus in front of the 8 to get a left-aligned padded string

answered Feb 13 '12 at 14:16

Bernd Elkemann

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True, but not what the OP asked for. – Dirk Eddelbuettel Feb 13 '12 at 14:18
3

It is not? He writes "But how can I get the additional whitespace at the END of the string?" or do i have something confused? – Bernd Elkemann Feb 13 '12 at 14:29
1

@DirkEddelbuettel The OP did ask for the whitespace at the end, so I think this fits that – James Feb 13 '12 at 14:29
1

This IS exactly what I want. Thanks for helping out a C newbie. I can only +acc one answer, but +1`d both. Thanks for the help and additional info. – Matt Bannert Feb 13 '12 at 14:30
1

You are correct--I misread from his example. He got left-padding, and I thought he wanted left-padding. My bad, sorry. It was a poorly worded question. – Dirk Eddelbuettel Feb 13 '12 at 14:31
@DirkEddelbuettel _"He got left-padding, and I thought he wanted left-padding."_ Riiiighhhttt.... ;-) – KomodoDave Jan 21 '14 at 00:51

Dirk Eddelbuettel · Answer 2 · 2012-02-13T14:33:57.320

12

That is almost more of a standard "C" rather than R question as it pertains to printf format strings. You can even test this on a command-prompt:

edd@max:~$ printf "[% 8s]\n" foo
[     foo]
edd@max:~$ printf "[%-8s]\n" foo
[foo     ]
edd@max:~$

and in R it works the same for padding left:

R> vec <- c("fjdlksa01dada","rau","sjklf")
R> sprintf("% 8s", vec)
[1] "fjdlksa01dada" "     rau"      "   sjklf"     
R>

and right

R> sprintf("%-8s", vec)
[1] "fjdlksa01dada" "rau     "      "sjklf   "     
R>

Edit: Updated once I understood better what @ran2 actually asked for.

edited Feb 13 '12 at 14:33

answered Feb 13 '12 at 14:15

Dirk Eddelbuettel

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Is there a direct way to add trailing `0`s instead of whitespaces using `sprintf()`? I am currently wrapping the outcome in `gsub(" ", "0", ...)`, which feels a bit cumbersome. – fdetsch Jan 20 '21 at 14:07

score 1 · Answer 3 · answered Aug 30 '16 at 20:35

1

The stringr package provides str_pad:

library(stringr)
x <- c("fjdlksa01dada","rau","sjklf")
str_pad(x, width=8, side="right")

which yields:

[1] "fjdlksa01dada" "rau     "      "sjklf   "

answered Aug 30 '16 at 20:35

Ryan C. Thompson

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How to use R's sprintf to create fixed width strings with fill whitespace at the END?

3 Answers3

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