Since you’re in control of varlist, you could simplify this at least once
by using symbols from the beginning. Next, you can use the symbol function
and a different overload of string instead of convert to make the
concat-convert operation a little less ugly:
julia> using DataFrames
julia> df = DataFrame(A = rand(5), B = rand(5), C = rand(5), D = rand(5))
5x4 DataFrames.DataFrame
| Row | A | B | C | D |
|-----|----------|----------|----------|----------|
| 1 | 0.550768 | 0.464531 | 0.141101 | 0.754492 |
| 2 | 0.629269 | 0.100223 | 0.981175 | 0.035041 |
| 3 | 0.26019 | 0.962588 | 0.948283 | 0.51513 |
| 4 | 0.755892 | 0.202503 | 0.727609 | 0.255172 |
| 5 | 0.28018 | 0.328776 | 0.684717 | 0.502154 |
julia> varlist = [:B,:C]
2-element Array{Symbol,1}:
:B
:C
julia> for i in eachindex(varlist)
rename!(df, varlist[i], symbol(string(varlist[i], i)))
end
julia> df
5x4 DataFrames.DataFrame
| Row | A | B1 | C2 | D |
|-----|----------|----------|----------|----------|
| 1 | 0.550768 | 0.464531 | 0.141101 | 0.754492 |
| 2 | 0.629269 | 0.100223 | 0.981175 | 0.035041 |
| 3 | 0.26019 | 0.962588 | 0.948283 | 0.51513 |
| 4 | 0.755892 | 0.202503 | 0.727609 | 0.255172 |
| 5 | 0.28018 | 0.328776 | 0.684717 | 0.502154 |
I usually think of symbols as "strings with some constraints", and using
one instead of the other then becomes quite trivial, conceptually.
// T
On Friday, May 8, 2015 at 8:27:18 PM UTC+2, Nils Gudat wrote:
I've been trying to rename a bunch of columns in a DataFrame and as a
> former pandas user am a bit thrown off by the way columns are accessed
> using symbols.
> Let's say I have a list of column names (strings) which I want to all give
> the same name with ascending integers at the end. After a few unsuccesful
> attempts, I came up with the following, but I feel like there has to be a
> less ugly way of doing this:
>
> df = DataFrame(A = rand(5), B = rand(5), C = rand(5), D = rand(5))
> varlist = ["B", "C"]
>
> for i = 1:length(varlist)
> rename!(df, convert(Symbol, varlist[i])), convert(Symbol,
> "column_"*string(i))
> end
>
