How to pass column name with function readtable in julia? - dataframe

Question

using DataFrames
label = ["Data", "tempo", "RAh", "RAm", "RAs", "DEh", "DEm", "DEs"]
df = readtable("mars.dat", separator = ' ',header = false, names = label)
I get the next error
MethodError: no method matching DataFrames.ParseOptions(::Bool, ::Char, ::Array{Char,1}, ::Char, ::Array{String,1}, ::Array{String,1}, ::Array{String,1}, ::Bool, ::Array{String,1}, ::Array{Any,1}, ::Bool, ::Char, ::Bool, ::Int64, ::Array{Int64,1}, ::Bool, ::Symbol, ::Bool, ::Bool)
Closest candidates are:
DataFrames.ParseOptions(::Bool, ::Char, ::Array{Char,1}, ::Char, ::Array{S<:String,1}, ::Array{T<:String,1}, ::Array{T<:String,1}, ::Bool, ::Array{Symbol,1}, ::Array{T,1} where T, ::Bool, ::Char, ::Bool, ::Int64, ::AbstractArray{Int64,1}, ::Bool, ::Symbol, ::Bool, ::Bool) where {S<:String, T<:String} at /home/juser/.julia/v0.6/DataFrames/src/dataframe/io.jl:9
Stacktrace:
[1] #readtable#84(::Bool, ::Char, ::Array{Char,1}, ::Char, ::Array{String,1}, ::Array{String,1}, ::Array{String,1}, ::Bool, ::Int64, ::Array{String,1}, ::Array{Any,1}, ::Bool, ::Char, ::Bool, ::Int64, ::Array{Int64,1}, ::Bool, ::Symbol, ::Bool, ::Bool, ::DataFrames.#readtable, ::IOStream, ::Int64) at /home/juser/.julia/v0.6/DataFrames/src/dataframe/io.jl:843
[2] (::DataFrames.#kw##readtable)(::Array{Any,1}, ::DataFrames.#readtable, ::IOStream, ::Int64) at ./<missing>:0
[3] #readtable#85(::Bool, ::Char, ::Array{Char,1}, ::Char, ::Array{String,1}, ::Array{String,1}, ::Array{String,1}, ::Bool, ::Int64, ::Array{String,1}, ::Array{Any,1}, ::Bool, ::Char, ::Bool, ::Int64, ::Array{Int64,1}, ::Bool, ::Symbol, ::Bool, ::Bool, ::DataFrames.#readtable, ::String) at /home/juser/.julia/v0.6/DataFrames/src/dataframe/io.jl:945
[4] (::DataFrames.#kw##readtable)(::Array{Any,1}, ::DataFrames.#readtable, ::String) at ./<missing>:0

Answer 1

From the documentation for readtable, it seems it expects a vector of symbols, not a vector of strings:
names::Vector{Symbol} – Use the values in this array as the names for all columns instead of or in lieu of the names in the file's header.
You can convert your vector of strings to a vector of symbols (assuming your strings are valid names) with a list comprehension, e.g.
labelSymbols = [Symbol(i) for i in label];
and pass this to your names parameter.
Disclaimer: I have not tested to see if this works as I don't have access to the mars.dat file. I'm just reading the docs and pointing out the most likely problem.