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--- tools:r [2023/09/30 20:58] – more text, link tidyverse will
+++ tools:r [2025/07/22 17:01] (current) – [na.action] vid79
@@ Line 1: / Line 1: @@
-=== GNU R ===
+====== GNU R ======
 The [[https://www.r-project.org/|GNU R programming language]] is often paired with [[https://posit.co/download/rstudio-desktop/|posit's RStudio Desktop IDE]] and a suit of libraries (language packages) known as [[:tools:tidyverse|tidyverse]] (includes ''dplyr'' and ''ggplot2'').
-You can also find a web interface to [[http://rhea.wpic.upmc.edu:8787/|Rstudio on rhea]] (also [[:admin:remoteaccess|Remote Access]]).
+You can also find a web interface to [[http://rhea.wpic.upmc.edu:8787/|Rstudio on rhea]] (also [[:admin:remoteaccess]]).
 [[:tools:tutorials|Tutorials]] contains additional resources.
+See [[:tools:r:issues]] for log of debugged problems.
+===== Notes =====
+==== na.action for residual ====
+When adding module residuals back to a dataframe, you need ''residuals()'' to return the same length as the input data.frame. use ''lm(na.action=na.exclude)''.
+For example,
+<code=R>
+d <-  data.frame(x=c(1:4,NA),y=1:5);
+m <- lm(x~y,d,na.action=na.exclude);
+nrow(d);              # 5
+length(m$residuals);  # 4
+length(residuals(m))  # 5
+</code>
+This avoids the error
+  Error in `$<-.data.frame`(`*tmp*`, ...
+    replacement has 237 rows, data has 348
+==== MASS::select vs dplyr::select  ====
+If you load MASS after dplyr, ''select'' will be ''MASS::select'' not ''dplyr::select'' and you're likely to encounter hard-to-debug errors about unused arguments
+> Error in select ...  : unused arguments
+**solutions** include
+  - load MASS first
+  - force select to be ''dplyr'''s version, or
+  - unload MASS if you don't need it
+<code>
+# load mass before dplyr to have 'select' be from dplyr
+library(MASS)
+library(dplyr)
+# force which select (if MASS was already loaded after dplyr and overwrite the function)
+select <- dplyr::select
+# or unload MASS
+detach("package:MASS", unload=TRUE)
+# check to see
+environment(select) # if "MASS", you're in for a bad time
+</code>
+===== Backlinks =====
 {{backlinks>.}}