根据data.frame的行值创建一个新变量

Question

I am new to R and not very familiar with the language.

I have a simple data frame in R. I'd like to add a blank column and then write some simple formulas to populate the new column for each row, based on the data in the columns of the respective row. Here is an example of the data frame:

ID Age BP Chl DM 
1 57 120 5 Y
2 87 134 7.5 N
3 95 111 6 Y

I would then like to add a new column, which would be populated with a formula. For example, for a given ID: if Age 40-59 AND BP 100-120 AND Chl <4 AND DM "N" = "10".

What package and function in R could I use to do this? Many thanks.

Answer 1

Imagine you have three conditions:

1. Age > 50 & BP < 100
2. Age > 50 & BP >= 100
3. Age <=50

And you want to assing values v1 , v2 , v3 , respectively, and store them in a new variable.

dat$newvar = NA # creates a new variable filled with NAs
ind1 = dat$Age > 50 & dat$BP < 100
ind2 = dat$Age > 50 & dat$BP >= 100
ind3 = dat$Age <=50

dat$newvar[ind1] = v1
dat$newvar[ind2] = v2
dat$newvar[ind3] = v3

You can use the same approach with as many conditions you want, just make sure the conditions are mutually excluyent. Rows not matching any condition will remain NA .