mutate

how do I add multiple columns together to create a new variable without having to write out each existing variable in the mutate function. For example if I have 10 questions on a survey and I want to create a composite score based on a sum of these 10 questions, is there a way to do this without having to write out: var1 + var2 + var3 .... + var10?

Hi David, how do I change a value format? For example, in the course assignment we divide by 30 and get a long decimal value. How would I format it so that it only shows two decimal places or even, out of curiosity, as a percentage?

Question regarding overwriting a variable with itself. I'm always nervous about doing this, in case I mess up. On the other hand, I can see where creating new variables and keeping the old ones can easily get out of hand and/or require using the drop pipe a lot. If I want to overwrite a variable onto itself is there an easy way to undo the mutate if I make a mistake?

When the values are changed, like rounding values, how come it doesn't show in the dataset tab? Or, have I forgotten something? For example, the output still shows the rounded values when I select the variable. But other than clean_names, the changes don't appear in the dataset. Thanks!

I typically keep both a numeric and a character variable. Here's a quick explanation of why.

Can you help me better understand the round function? I don't understand the digits part? Does it only apply to decimals? What if you want to round to the nearest whole number what would you put? Or to round to the nearest 10?

Hi, I have a column that I would like to split into three. The data in the existing column looks like the following, and I would like it to feed into three new columns: id, bio, and username.

{"id":"1234567","bio":"John Smith, first-year undergraduate in Physics","username":"JSAstronaut"}

All rows follow this exact format (although the bio part may be longer), so I feel there must be a simple way to do, and I was just wondering if anyone has suggestions. Or is this going to be covered at a later point in the courses? So far I have tried the separate function in tidyr, but it hasn't quite turned out to be the way I hoped.

I'd appreciate any pointers. Thank you!

Hi What if I wanted to create a new variable for a subset of groups with one type and then another set of groups with another For example, if I wanted to only create a new variable for "Females" with country = United States, but then select only "Males" with country = Canada. I tried to do the following as a best guess nhanes %>% mutate(completed_survey = "Yes") select(contains("female"))