[R] Subset

[Boris Steipe]

myDF <- data.frame(a = c("<0.1", NA, 0.3, 5, "Nil"),
                   b = c("<0.1", 1, 0.3, 5, "Nil"),
                   stringsAsFactors = FALSE)

# you can subset the b-column in several ways

myDF[ , 2]
myDF[ , "b"]
myDF$b

# using the column, you make a logical vector
! is.na(as.numeric(myDF$b))


# This can be used to select the rows you want

myDF[! is.na(as.numeric(myDF$b)), ]



B.


> On Sep 25, 2017, at 7:30 AM, Shane Carey <careyshan at gmail.com> wrote:
> 
> Hi,
> 
> Lets say this was a dataframe where I had two columns
> 
> a <- c("<0.1", NA, 0.3, 5, "Nil")
> b <- c("<0.1", 1, 0.3, 5, "Nil")
> 
> And I just want to remove the rows from the dataframe where there were NAs in the b column, what is the syntax for doing that?
> 
> Thanks in advance
> 
> On Fri, Sep 22, 2017 at 5:04 PM, Shane Carey <careyshan at gmail.com> wrote:
> Super,
> 
> Thanks
> 
> On Fri, Sep 22, 2017 at 4:57 PM, Boris Steipe <boris.steipe at utoronto.ca> wrote:
> > a <- c("<0.1", NA, 0.3, 5, "Nil")
> > a
> [1] "<0.1" NA     "0.3"  "5"    "Nil"
> 
> > b <- as.numeric(a)
> Warning message:
> NAs introduced by coercion
> > b
> [1]  NA  NA 0.3 5.0  NA
> 
> > b[! is.na(b)]
> [1] 0.3 5.0
> 
> 
> B.
> 
> 
> > On Sep 22, 2017, at 11:48 AM, Shane Carey <careyshan at gmail.com> wrote:
> >
> > Hi,
> >
> > How do I extract just numbers from the following list:
> >
> > a=c("<0.1",NA,0.3,5,Nil)
> >
> > so I want to obtain: 0.3 and 5 from the above list
> >
> > Thanks
> >
> >
> > --
> > Le gach dea ghui,
> > *Shane Carey*
> > *GIS and Data Solutions Consultant*
> >
> >       [[alternative HTML version deleted]]
> >
> > ______________________________________________
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> > 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.
> 
> 
> 
> 
> -- 
> Le gach dea ghui,
> Shane Carey
> GIS and Data Solutions Consultant
> 
> 
> 
> -- 
> Le gach dea ghui,
> Shane Carey
> GIS and Data Solutions Consultant