julia dataframe增加row的方法

两种途径
（1）给定的是一个数组（一行）的话，直接用push!
（2）如果给定的是一个dataframe的话，直接用append!

在给定的一行（格式为数组）时，没有必要把它变成dataframe再使用append

一、给定ary， 直接push到df中

function test4()
    df = DataFrame(A = Int64[], B = Int64[],C = String[])
    
    for i in 1:1000000
        push!(df, [3,6,"朱"])
    end  
end

@time test4() 
#1.022286 seconds (9.00 M allocations: 259.091 MiB, 1.77% gc time)

二、给定ary， 首先生成df再append到df中

function test5()
    df = DataFrame(A = Int64[], B = Int64[],C = String[])
    for i in 1:1000000        
        sss = [3,6,"朱"]
        col = [:A,:B,:C]
        ary = sss.|>(item) -> [item]
        df1 = DataFrame(ary,col)
        append!(df,df1)        
    end
end

@time test5() 
# 13.809428 seconds (81.06 M allocations: 5.247 GiB, 4.48% gc time)

三、给定的df1， 直接append到df中

function test6()
    df = DataFrame(A = Int64[], B = Int64[],C = String[])
    
    sss = [3,6,"朱"]
    col = [:A,:B,:C]
    ary = sss.|>(item) -> [item]
    df1 = DataFrame(ary,col)
    
    for i in 1:1000000        
        append!(df,df1)        
    end
end

@time test6() 
#0.958618 seconds (15.06 M allocations: 774.894 MiB, 6.50% gc time)