[R] Error: Cannot use `+.gg()` with a single argument.

[Rui Barradas]

Hello,

Richard's answer solves the problem, I'm writing about details in the 
OP's post.

Ana, your code example is missing some library() calls:

library(ggplot2)
library(ggrepel)
library(ggthemes)
library(dplyr)

# and where to find the data set
data(murders, package = "dslabs")


As for the dplyr pipe, you end it with .$rate to pull only that column's 
value, the following avoids that construct and is, I believe, more 
idiomatic:

#define the slope of the line
r <- murders %>%
   summarize(rate = sum(total)/sum(population)*10^6) %>%
   pull(rate)


Hope this helps,

Rui Barradas


Às 04:27 de 08/05/20, Richard M. Heiberger escreveu:
> It is just like the message suggested. You have a + at the end of each line
> and
> the beginning of the next.  The one at the end is required.  The ones at
> the beginning are
> causing the error message.
> 
> Please put spaces around your assignment arrows.
> Difficult to read:  r<-murders
> Easy to read:    r <- murders
> 
> On Thu, May 7, 2020 at 10:46 PM Ana Marija <sokovic.anamarija using gmail.com>
> wrote:
> 
>> Hello,
>>
>> I got this error:
>> Error: Cannot use `+.gg()` with a single argument. Did you
>> accidentally put + on a new line?
>>
>> After running this:
>> data(murders)
>> library(ggplot2)
>> library(dplyr)
>> library(ggplot2)
>> ggplot(data=murders)
>>
>> #define the slope of the line
>> r<-murders %>% summarize(rate=sum(total)/sum(population)*10^6) %>%.$rate
>> #mamke the plot
>> murders %>% ggplot(aes(population/10^6,total,label=abb))+
>>    +geom_abline(intercept = log10(r),lty=2,color="darkgrey")+
>>    +geom_point(aes(col=region), size=3)+
>>    +geom_text_repel()+
>>    +scale_x_log10()+
>>    +scale_y_log10()+
>>    +xlab("Populations in millions (log scale)")+
>>    +ylab("Total number of murders (log scale)")+
>>    +ggtitle("US Gun Murders in US 2010")+
>>    +scale_color_discrete(name="Region")+
>>    +theme_economist()
>>
>> Is this an issue with my dplyr? Or how I can fix this code in order to
>> work?
>>
>> Thanks
>> Ana
>>
>> ______________________________________________
>> R-help using 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.
>>
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>