Re: [R] Read code from character string
Gabor Grothendieck ggrothendi...@gmail.com [Sat, Jun 19, 2010 at 11:19:35AM CEST]: On Sat, Jun 19, 2010 at 4:56 AM, Johannes Huesing johan...@huesing.name wrote: A rule would be a data structure containing the ID of the rule, the rule in human readable language, an expression evaluating variables within the environment of the appropriate data frame (and resolving to a logical vector), possibly the data frame itself, and the query message (possibly as an sprintf expression). The data structure may be an S4 object or a list. In our current workflow, we manage the validation rules using a spreadsheet, and import them into a competitor's analysis software. I could pass function(df) with(df, (vsstresn 30 | vsstresn 130) vstestcd == HR) Another possibility would be to use an sql statement or fragment so if you passed this sql fragment: fragment - (vsstresn 30 or vsstresn 130) and vstestcd = 'HR' # then your program would run this code: df - data.frame(vsstresn = seq(10, 200, 10), vstestcd = rep(c(HR, RH), c(16, 4))) library(sqldf) sqldf(paste(select * from df where, fragment)) vsstresn vstestcd 1 10 HR 2 20 HR 3 140 HR 4 150 HR 5 160 HR Many thanks! (ok, next time I will post a data example myself.) Is this a corollary of fortune 106: If the answer is eval(parse()), you should reconsider the language? -- Johannes Hüsing There is something fascinating about science. One gets such wholesale returns of conjecture mailto:johan...@huesing.name from such a trifling investment of fact. http://derwisch.wikidot.com (Mark Twain, Life on the Mississippi) __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Read code from character string
Greg Snow greg.s...@imail.org [Sat, Jun 19, 2010 at 12:44:48AM CEST]: There are a lot of other reasons to install the fortunes package that just the one fortune, there is much wisdom, some wit, (and then there are mine) throughout the package. Sorry, but I am subscribing to r-help already. I could not possibly handle more wisdom and wit than this. There could be other ways to accomplish your goals, if you let us know more about what you are trying to do, we may be able to help you find a better way (that does not mean that you cannot still use eval and parse, but you may learn something, and/or avoid future pitfalls). Ok, I want to demonstrate for educational purposes how to construct a set of rules to validate a set of clinical data, and to make it issue and export appropriate query messages. A rule would be a data structure containing the ID of the rule, the rule in human readable language, an expression evaluating variables within the environment of the appropriate data frame (and resolving to a logical vector), possibly the data frame itself, and the query message (possibly as an sprintf expression). The data structure may be an S4 object or a list. In our current workflow, we manage the validation rules using a spreadsheet, and import them into a competitor's analysis software. I could pass function(df) with(df, (vsstresn 30 | vsstresn 130) vstestcd == HR) as an argument, but function(df) with(df, is sort of redundant, as I expect it to be in every expression, plus it doesn't add much clarity for the people writing and reading these conditions. [...] Personally I have never regretted trying not to underestimate my own future stupidity. -- Greg Snow (explaining why eval(parse(...)) is often suboptimal, answering a question triggered by the infamous fortune(106)) R-help (January 2007) Don't get me started about my current stupidity. -- Johannes Hüsing There is something fascinating about science. One gets such wholesale returns of conjecture mailto:johan...@huesing.name from such a trifling investment of fact. http://derwisch.wikidot.com (Mark Twain, Life on the Mississippi) __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Read code from character string
On Sat, Jun 19, 2010 at 4:56 AM, Johannes Huesing johan...@huesing.name wrote: A rule would be a data structure containing the ID of the rule, the rule in human readable language, an expression evaluating variables within the environment of the appropriate data frame (and resolving to a logical vector), possibly the data frame itself, and the query message (possibly as an sprintf expression). The data structure may be an S4 object or a list. In our current workflow, we manage the validation rules using a spreadsheet, and import them into a competitor's analysis software. I could pass function(df) with(df, (vsstresn 30 | vsstresn 130) vstestcd == HR) Another possibility would be to use an sql statement or fragment so if you passed this sql fragment: fragment - (vsstresn 30 or vsstresn 130) and vstestcd = 'HR' # then your program would run this code: df - data.frame(vsstresn = seq(10, 200, 10), vstestcd = rep(c(HR, RH), c(16, 4))) library(sqldf) sqldf(paste(select * from df where, fragment)) vsstresn vstestcd 1 10 HR 2 20 HR 3 140 HR 4 150 HR 5 160 HR __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Read code from character string
Peter Langfelder peter.langfel...@gmail.com [Thu, Jun 17, 2010 at 09:38:45PM CEST]: eval(parse(text=print(9**2))) cheers, I overlooked the text option. On Thu, Jun 17, 2010 at 12:32 PM, Johannes Huesing johan...@huesing.name wrote: Dear expRts, I have a character string, say a - print(9**2). How do I execute the contents of the string, parsed as R code? Do I have to open a connection and use cat(a), and parse it at the other end? -- Johannes Hüsing There is something fascinating about science. One gets such wholesale returns of conjecture mailto:johan...@huesing.name from such a trifling investment of fact. http://derwisch.wikidot.com (Mark Twain, Life on the Mississippi) __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Read code from character string
You should also look at fortune(106) and think about possible other solutions to your overall objective. -- Gregory (Greg) L. Snow Ph.D. Statistical Data Center Intermountain Healthcare greg.s...@imail.org 801.408.8111 -Original Message- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r- project.org] On Behalf Of Johannes Huesing Sent: Friday, June 18, 2010 12:17 AM To: Peter Langfelder Cc: r-h...@stat.math.ethz.ch Subject: Re: [R] Read code from character string Peter Langfelder peter.langfel...@gmail.com [Thu, Jun 17, 2010 at 09:38:45PM CEST]: eval(parse(text=print(9**2))) cheers, I overlooked the text option. On Thu, Jun 17, 2010 at 12:32 PM, Johannes Huesing johan...@huesing.name wrote: Dear expRts, I have a character string, say a - print(9**2). How do I execute the contents of the string, parsed as R code? Do I have to open a connection and use cat(a), and parse it at the other end? -- Johannes Hüsing There is something fascinating about science. One gets such wholesale returns of conjecture mailto:johan...@huesing.name from such a trifling investment of fact. http://derwisch.wikidot.com (Mark Twain, Life on the Mississippi) __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting- guide.html and provide commented, minimal, self-contained, reproducible code. __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Read code from character string
Greg Snow greg.s...@imail.org [Fri, Jun 18, 2010 at 04:57:03PM CEST]: You should also look at fortune(106) and think about possible other solutions to your overall objective. I am not installing fortune solely for this purpose but I understand that anything which smells like macro expansion is frowned upon in R circles. Yet there are situations where i want to treat code as data and data as code. As far as I gather this works only with closures in R, not with general S-expressions, so sometimes I have to resort to character strings. -- Johannes Hüsing There is something fascinating about science. One gets such wholesale returns of conjecture mailto:johan...@huesing.name from such a trifling investment of fact. http://derwisch.wikidot.com (Mark Twain, Life on the Mississippi) __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Read code from character string
There are a lot of other reasons to install the fortunes package that just the
one fortune, there is much wisdom, some wit, (and then there are mine)
throughout the package.
There could be other ways to accomplish your goals, if you let us know more
about what you are trying to do, we may be able to help you find a better way
(that does not mean that you cannot still use eval and parse, but you may learn
something, and/or avoid future pitfalls).
fortune(106)
If the answer is parse() you should usually rethink the question.
-- Thomas Lumley
R-help (February 2005)
fortune('106')
Personally I have never regretted trying not to underestimate my own future
stupidity.
-- Greg Snow (explaining why eval(parse(...)) is often suboptimal, answering
a question triggered by the infamous fortune(106))
R-help (January 2007)
--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.s...@imail.org
801.408.8111
-Original Message-
From: Johannes Huesing [mailto:johan...@huesing.name]
Sent: Friday, June 18, 2010 2:57 PM
To: Greg Snow
Cc: Peter Langfelder; r-h...@stat.math.ethz.ch
Subject: Re: [R] Read code from character string
Greg Snow greg.s...@imail.org [Fri, Jun 18, 2010 at 04:57:03PM CEST]:
You should also look at fortune(106) and think about possible other
solutions to your overall objective.
I am not installing fortune solely for this purpose but I understand
that anything which smells like macro expansion is frowned upon in R
circles.
Yet there are situations where i want to treat code as data and
data as code. As far as I gather this works only with closures in R,
not with general S-expressions, so sometimes I have to resort to
character strings.
--
Johannes Hüsing There is something fascinating about
science.
One gets such wholesale returns of
conjecture
mailto:johan...@huesing.name from such a trifling investment of fact.
http://derwisch.wikidot.com (Mark Twain, Life on the
Mississippi)
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
[R] Read code from character string
Dear expRts, I have a character string, say a - print(9**2). How do I execute the contents of the string, parsed as R code? Do I have to open a connection and use cat(a), and parse it at the other end? Cheers Johannes -- Johannes Hüsing There is something fascinating about science. One gets such wholesale returns of conjecture mailto:johan...@huesing.name from such a trifling investment of fact. http://derwisch.wikidot.com (Mark Twain, Life on the Mississippi) __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Re: [R] Read code from character string
eval(parse(text=print(9**2))) On Thu, Jun 17, 2010 at 12:32 PM, Johannes Huesing johan...@huesing.name wrote: Dear expRts, I have a character string, say a - print(9**2). How do I execute the contents of the string, parsed as R code? Do I have to open a connection and use cat(a), and parse it at the other end? __ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
