How to change row's values of a column matching pattern in Julia?

I have a dataframe where some rows of a given column (‘group’) have a certain value (‘normal’). I would like to change such a value to something else. What would be the syntax? In other words, I am looking for Julia’s equivalent to R’s
df$group[df32$group == "Normal"] <- "Healthy"
And what would be the syntax for renaming the whole column?
Thank you

There are two easy ways to do what you want.

df = DataFrame(group=["foo", "notfoo", "foo"], data = 1:3)

Using replace

replace!(, "foo" => "bar")
group data
String Int64
1 bar 1
2 notfoo 2
3 bar 3

Or by indexing as you do in your example

df[ .== "foo","group"] .= "bar"

Both of these will do the change inplace.

1 Like

Thank you. And if I wanted to change the whole column group to “unknown”, for instance?

In that case you can use the bang operator and broadcasting to assign a new value to the whole column

df[!,"group"] .= "unknown"

You can find some more details on the different ways of accessing the data in this blog post