library(dslabs)suppressMessages(library(dplyr))library(stringr) #necessary packagesdata(murders) #get data from dslabshead(murders) #gives the first 6 row from data set
state abb region population total
1 Alabama AL South 4779736 135
2 Alaska AK West 710231 19
3 Arizona AZ West 6392017 232
4 Arkansas AR South 2915918 93
5 California CA West 37253956 1257
6 Colorado CO West 5029196 65
is.numeric(murders$population)#if we use assert_is_numeric(murders$state) the output would be"murders$state is not class 'numeric'; it has class chr. (You should install required packages for use assert_is_ functions.)
[1] TRUE
revenue_trimmed =str_remove(murders$abb, "A") #if we would like to remove a chr from a string we can use str_remove func.revenue_trimmed
head(murders %>%mutate(new_column = revenue_trimmed)) #add a new column to a data frame
state abb region population total new_column
1 Alabama AL South 4779736 135 L
2 Alaska AK West 710231 19 K
3 Arizona AZ West 6392017 232 Z
4 Arkansas AR South 2915918 93 R
5 California CA West 37253956 1257 C
6 Colorado CO West 5029196 65 CO
summary(murders$population) #calculate min, 1st Qu, median, mean, 3rd Qu and max values for the variable.
Min. 1st Qu. Median Mean 3rd Qu. Max.
563626 1696962 4339367 6075769 6636084 37253956