# Matching/checking for occurence when values are double?

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## Matching/checking for occurence when values are double?

 I need to pick from a dataset those rows that have a double value set to 100. However since the values in this column are like the following: [1] 121.11750  89.36188 115.44320  99.44964  92.74571 107.90180 [7] 138.89310 125.14510  81.61953  95.07307  88.57700  94.85971 [13]  88.96280 114.11430 100.53410 120.41910 114.42690 … Then can I match against 100 or 100.0? Or do I need to match against 100.00000 or something else? E.g. does 100.0 %in% kidmomiq\$mom_iq produce a truthful match result with this kind of data (I’m getting 0 occurrences, which might be correct, but I’m not sure)? ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: Matching/checking for occurence when values are double?

 Hello, See FAQ 7.31. It's irrelevant if you write 100 or 100.0, the values are the same.   The difference would be between 100 (double) and 100L (integer). To check for equality between floating-point numbers you can use, for   instance, the following function. equal <- function(x, y, eps = .Machine\$double.eps^0.5) abs(x - y) < eps equal(100, 100 + 2e-15) [1] TRUE Hope this helps, Rui Barradas Citando Matti Viljamaa <[hidden email]>: > I need to pick from a dataset those rows that have a double value set to 100. > However since the values in this column are like the following: > > [1] 121.11750  89.36188 115.44320  99.44964  92.74571 107.90180 > [7] 138.89310 125.14510  81.61953  95.07307  88.57700  94.85971 > [13]  88.96280 114.11430 100.53410 120.41910 114.42690 > … > > Then can I match against 100 or 100.0? Or do I need to match against   > 100.00000 or something else? > > E.g. does > > 100.0 %in% kidmomiq\$mom_iq > > produce a truthful match result with this kind of data (I’m getting   > 0 occurrences, which might be correct, but I’m not sure)? > ______________________________________________ > [hidden email] mailing list -- To UNSUBSCRIBE and more, see > 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. ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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## Re: Matching/checking for occurence when values are double?

 In reply to this post by mavavilj Matching 100 to 100.0 or 100.00 or whatever N number of decimales will always return a TRUE. The expression your using is correct. A more complete expression would be kidmomiq[100 == kidmomiq\$mom_iq, ]. On Fri, Sep 9, 2016 at 2:01 PM, Matti Viljamaa <[hidden email]> wrote: I need to pick from a dataset those rows that have a double value set to > 100. > However since the values in this column are like the following: > > [1] 121.11750  89.36188 115.44320  99.44964  92.74571 107.90180 > [7] 138.89310 125.14510  81.61953  95.07307  88.57700  94.85971 > [13]  88.96280 114.11430 100.53410 120.41910 114.42690 > … > > Then can I match against 100 or 100.0? Or do I need to match against > 100.00000 or something else? > > E.g. does > > 100.0 %in% kidmomiq\$mom_iq > > produce a truthful match result with this kind of data (I’m getting 0 > occurrences, which might be correct, but I’m not sure)? > ______________________________________________ > [hidden email] mailing list -- To UNSUBSCRIBE and more, see > 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.         [[alternative HTML version deleted]] ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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