On Feb 1, 2010, at 11:36 AM, David Winsemius wrote:
On Feb 1, 2010, at 11:11 AM, Jerry Floren wrote:
HI,
I am using Windows XP and R version 2.9.2. I have a data frame
written by R
similar to the following:
Lab_ID Analysis_Soil Results -4MAD -2.5MAD
+2.5MAD +4MAD
55003 Calcium-2008-116 900 961 1121.5
1656.5 1817
55003 Calcium-2008-117 3321 2175 2380.5
3065.5 3271
55003 Calcium-2008-118 3342 3155 4019
6899 7763
55003 Calcium-2008-119 1664 1005.6
1147.92 1622.32
1764.64
55003 Calcium-2008-120 2570 1880
2072 2712
2904
Previously, I took this table and finished my analysis in Excel using
Excel's "=if" function.
I'll bet that was painful.
However, I am sure it can be done in R. What I want
to do is set up a new data.frame with a new column for Accuracy Flags
(a_flag) as shown below.
Lab_ID Analysis_Soil Results -4MAD -2.5MAD
+2.5MAD +4MAD a_flag
55003 Calcium-2008-116 900 961 1121.5
1656.5 1817 **L
55003 Calcium-2008-117 3321 2175 2380.5
3065.5 3271 **H
55003 Calcium-2008-118 3342 3155 4019
6899 7763 *L
55003 Calcium-2008-119 1664 1005.6
1147.92 1622.32
1764.64 *H
55003 Calcium-2008-120 2570 1880
2072 2712
2904
df.soil$a_flag <- apply(df.soil, 1, function(.x)
switch(findInterval(.x$Result, c(-Inf,-4,-2.5,2.5,4,Inf)) ,
"**L", "*L", " ", "*H",
"**H") )
Sorry I didn't note the irregularity of the limits. Try instead:
df.soil$a_flag <- apply(df.soil, 1, function(.x)
switch(findInterval(.x[3], as.numeric( c(-Inf,.x[4:7],Inf)) ),
"**L", "*L", " ", "*H",
"**H") )
I wasn't sure why the passage of the function made it necessary to add
the as.numeric, but I am guessing that .x became a character vector in
order to hold the first two columns. That would not be be needed, it
you only passed the last 5 columns as df.soil[3:7] as an argument to
apply.
For each row I need to compare the "Results" submitted by the labs
to the
four "MAD" columns. If the Results are less than -4.0 MAD units
from the
median, labs are flagged "**L" (very low). For results greater than
+4.0 MAD
units, labs are flagged "**H" (very high). Likewise for -2.5 MAD
and +2.5
MAD (*L and *H respectively). As shown in the last row, labs are
not flagged
for results within -2.5 MAD to +2.5 MAD units.
Can anyone get me started on how to look at each row and compare the
"Results" variable with each of the four "__MAD" variables and then
writing
the appriate flag for Results exceeding -2.5 MAD to +2.5 MAD units
from the
median?
Thanks,
Jerry Floren
Minnesota Department of Agriculture
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______________________________________________
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David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
David Winsemius, MD
Heritage Laboratories
West Hartford, CT
______________________________________________
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.
