R CONVERT CHARACTER TO NUMERIC CODE
R CONVERT CHARACTER TO NUMERIC SERIES

We love aggregators! Aggregators collect blogs that have similar coverage for the convenience of readers, and for blog authors they offer a way to reach new audiences. For the record, the use cases for this kind of recoding in R may be more strained than the SAS example given above. There's a warning in the documentation for factor() that the values are assigned in location-specific fashion, so the table should be used to establish how the codes were assigned. We can get them out with a call to as.numeric().Ĭat = c(rep('meow',30),rep('Hiss',30), rep('Purr', 40))Ĭatn1 = factor(cat, labels=(1:length(levels(factor(cat))))) Then we have numbers, but they're store as a factor.

R CONVERT CHARACTER TO NUMERIC CODE

There's probably a better way of doing this, but it's a little bit amusing to code it this way. Note that we find this using the factor() function again. To convert to numbers, we use the labels option to the factor() function, feeding it the sequences of numbers between 1 and however many different values there are. The table also shows the recoding values.

When we find a new value, we'll increase a counter by 1 the counter is our new numeric-valued variable. The set ds by x syntax makes new temporary variables first.x and last.x that are equal to 1 for the first and last observations of each new level of x, respectively, and 0 otherwise. It's hard to believe that we've never demonstrated this useful syntax before- perhaps we just can't find it today. To make the new variable, we'll just sort (section 1.5.6) the data on the categorical variable we want to convert, then use the set ds by x syntax to keep track of when a new value is encountered in the data.

But if you're not an IML coder, and you don't want to investigate a macro solution, it's simple enough to do with data steps. In SAS, Rick Wicklin offers an IML solution and links to a macro with the same function.

R CONVERT CHARACTER TO NUMERIC SERIES

One way to convert character variables to numeric values is to determine which values exist, then write a possibly long series of conditional tests to assign numbers to the values. For example, the matching macro we discussed in example 7.35 will only match on numeric variables. In some settings it may be necessary to recode a categorical variable with character values into a variable with numeric values.

R convert character to numeric