When i=1, both println(typeof("$i")) and println(typeof(:($("$i")))) give String, and both println("$i") and println(:($("$i"))) give 1. However, the following code
using DataFrames
df = DataFrame()
i = 1
df.:($("$i")) = [0.0]
println(df)
works, but the following code
using DataFrames
df = DataFrame()
i = 1
df."$i" = [0.0]
println(df)
does not work. What is wrong with the latter code?
I would not recommend you to rely on the either syntax. These are corner cases of Julia parser.
The fact that:
df.:($("$i")) = [0.0]
works is most likely not a conscious design decision on Julia parser side. Note that:
df.:($("$i"))
fails.
As it is explained in https://dataframes.juliadata.org/stable/man/getting_started/:
Note that in the forms
df."col"and:var"col"variable interpolation into a string using$does not work.
If you want to use interpolation either directly call setproperty! and getproperty or use getindex/setindex!, in this case:
df[!, "$i"] = [0.0]