R help - Oct 2011 - Comparing the components of a data frame without levels interfering

*Bottom Line: How can I compare the individual components of two data frames
with different row lengths without the levels interfering?*

Example: I have two data frames to those respectively named 'dfCity' and
'dfState' that have the following output:

dfCity
 
     Name       City 
1    Bill        Detroit 
2    Jody      Chicago
3    Frank    Memphis 
4    Ron       Houston 

dfState

     Name       State
1    Bill        Michigan
2    Frank    Tennessee  

I have an if statement that is trying to compare the individual's names and
combine the data from the two different data frames to produce some output: 
 
for(j in 1:length(row.names(dfState))){
			for(k in 1:length(row.names(dfCity))){
				if(dfCity[k,1] == dfState[j,1]){
					cityState <- paste(dfCity[k,2], ", ", dfState[j,2], sep=
"")
					print(dfCity[1, j], " is from ", cityState)
				}
			}
		}

However, when I run it I get the error /Error in Ops.factor(dfState[2, 1],
dfCity[4, 1]) : level sets of factors are different/ due to the levels in
the data frames. *How can I compare the individual components of the data
frame without the levels interfering? *

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Hi

> *Bottom Line: How can I compare the individual components of two data 
frames
> with different row lengths without the levels interfering?*
> 
> Example: I have two data frames to those respectively named
'dfCity' and
> 'dfState' that have the following output:
> 
> dfCity
> 
>      Name       City 
> 1    Bill        Detroit 
> 2    Jody      Chicago
> 3    Frank    Memphis 
> 4    Ron       Houston 
> 
> dfState
> 
>      Name       State
> 1    Bill        Michigan
> 2    Frank    Tennessee 
> 
> I have an if statement that is trying to compare the individual's names
and
> combine the data from the two different data frames to produce some 
output: 
> 
> for(j in 1:length(row.names(dfState))){
>          for(k in 1:length(row.names(dfCity))){
>             if(dfCity[k,1] == dfState[j,1]){
>                cityState <- paste(dfCity[k,2], ", ",
dfState[j,2], sep=
"") 
>                print(dfCity[1, j], " is from ", cityState)
>             }
>          }
>       }
What about first merge two data frames

mergedDF <- merge(dfCity, dfState, all=TRUE)

and after that you can do

cityState <- paste(mergedDF$City, ", ", mergedDF$State, sep=
"")

or anything you want.

Regards
Petr
> 
> However, when I run it I get the error /Error in Ops.factor(dfState[2, 
1],
> dfCity[4, 1]) : level sets of factors are different/ due to the levels 
in
> the data frames. *How can I compare the individual components of the 
data
> frame without the levels interfering? *
> 
> --
> View this message in context: 
http://r.789695.n4.nabble.com/Comparing-the-
> 
components-of-a-data-frame-without-levels-interfering-tp3900502p3900502.html
> Sent from the R help mailing list archive at Nabble.com.
> 
> ______________________________________________
> R-help at 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.

Factors include a comprehensive list of all possible values they can assume.
Your name columns have different numbers of names, so they are really very
different factors. The best solution for you is to convert those columns to
character.

You also ought to learn how to use the merge function before you write much code
like your example.
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swonder03 <ramey.steven@gmail.com> wrote:

*Bottom Line: How can I compare the individual components of two data frames
with different row lengths without the levels interfering?*

Example: I have two data frames to those respectively named 'dfCity' and
'dfState' that have the following output:

dfCity

Name City 
1 Bill Detroit 
2 Jody Chicago
3 Frank Memphis 
4 Ron Houston 

dfState

Name State
1 Bill Michigan
2 Frank Tennessee 

I have an if statement that is trying to compare the individual's names and
combine the data from the two different data frames to produce some output: 

for(j in 1:length(row.names(dfState))){
			for(k in 1:length(row.names(dfCity))){
				if(dfCity[k,1] == dfState[j,1]){
					cityState <- paste(dfCity[k,2], ", ", dfState[j,2], sep=
"")
					print(dfCity[1, j], " is from ", cityState)
				}
			}
		}

However, when I run it I get the error /Error in Ops.factor(dfState[2, 1],
dfCity[4, 1]) : level sets of factors are different/ due to the levels in
the data frames. *How can I compare the individual components of the data
frame without the levels interfering? *

--
View this message in context:
http://r.789695.n4.nabble.com/Comparing-the-components-of-a-data-frame-without-levels-interfering-tp3900502p3900502.html
Sent from the R help mailing list archive at Nabble.com.

_____________________________________________

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.


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