Finding Highest value in groups

Base R functions can handle this easily. It is preferable to use dput() as a compact way of providing data on the list:
dta <- read.table(text="ID    Value
+ 1        0.69
+ 1        0.31
+ 2        0.01
+ 2        0.99
+ 3        1.00
+ 4        NA
+ 4        0
+ 4        1
+ 5        0.5
+ 5        0.5
+ ", header=TRUE)
dput(dta)
structure(list(ID = c(1L, 1L, 2L, 2L, 3L, 4L, 4L, 4L, 5L, 5L), 
    Value = c(0.69, 0.31, 0.01, 0.99, 1, NA, 0, 1, 0.5, 0.5)), .Names = c("ID", 
"Value"), class = "data.frame", row.names = c(NA, -10L))

Then you just need the aggregate() function:
aggregate(Value~ID, dta, max, na.rm=TRUE)
ID Value
1  1  0.69
2  2  0.99
3  3  1.00
4  4  1.00
5  5  0.50

See ?aggregate for the help page.

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352

-----Original Message-----
From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Tom Wright
Sent: Friday, April 22, 2016 9:13 AM
To: Saba Sehrish
Cc: R-help Mailing List
Subject: Re: [R] Finding Highest value in groups

Assuming your dataframe is in a variable x:
require(dplyr)
x %>% group_by(ID) %>% summarise(maxVal = max(Value,na.rm=TRUE))

Hi

I have two columns in data frame. First column is based on "ID" assigned to each group of my data (similar ID depicts one group). From second column, I want to identify highest value among each group and want to assign the same ID to that highest value.

Right now the data looks like:

ID    Value
1        0.69
1        0.31
2        0.01
2        0.99
3        1.00
4        NA
4        0
4        1
5        0.5
5        0.5

I want to use R program to get results as below:

ID       Value
1        0.69
2        0.99
3        1.00
4        1
5        0.5

Kindly guide me in this regard.

Thanks
Saba

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______________________________________________
R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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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.

Finding Highest value in groups

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