minor improvement to formatting variable names in clustering

Author: trevorcampbell

source/clustering.Rmd

@@ -289,7 +289,7 @@ Then we would compute the coordinates, $\mu_x$ and $\mu_y$, of the cluster cente
 $$\mu_x = \frac{1}{4}(x_1+x_2+x_3+x_4) \quad \mu_y = \frac{1}{4}(y_1+y_2+y_3+y_4).$$
 
 In the first cluster from the example, there are `r nrow(clus1)` data points. These are shown with their cluster center 
-(`r paste("flipper_length_standardized =", round(mean(clus1$flipper_length_standardized),2))` and `r paste("bill_length_standardized =", round(mean(clus1$bill_length_standardized),2))`) highlighted 
+(standardized flipper length `r round(mean(clus1$flipper_length_standardized),2)`, standardized bill length `r round(mean(clus1$bill_length_standardized),2)`) highlighted 
 in Figure \@ref(fig:10-toy-example-clus1-center).
 
 (ref:10-toy-example-clus1-center) Cluster 1 from the `penguin_data` data set example. Observations are in blue, with the cluster center highlighted in red.