在Julia

Question

当我尝试将多个DataFrames（来自DataFrames包的数据结构！）与相同的列但不同的行号连接起来时，我遇到了问题。这是我的代码：

using(DataFrames)
DF = DataFrame()
DF[:x1]   = 1:1000
DF[:x2]   = rand(1000)
DF[:time] = append!( [0] , cumsum( diff(DF[:x1]).<0 ) ) + 1



DF1 = DF[DF[:time] .==1,:]
DF2 = DF[DF[:time] .==round(maximum(DF[:time])),:]
DF3 = DF[DF[:time] .==round(maximum(DF[:time])/4),:]
DF4 = DF[DF[:time] .==round(maximum(DF[:time])/2),:]

DF1[:T] = "initial"
DF2[:T] = "final"
DF3[:T] = "1/4"
DF4[:T] = "1/2"

DF = [DF1;DF2;DF3;DF4]

最后一行给出了错误

MethodError: Cannot `convert` an object of type DataFrames.DataFrame to an object of type LastMain.LastMain.LastMain.DataFrames.AbstractDataFrame
This may have arisen from a call to the constructor LastMain.LastMain.LastMain.DataFrames.AbstractDataFrame(...),
since type constructors fall back to convert methods.

我不明白这条错误信息。你能帮我吗？谢谢！

Answer 1

我刚刚在Julia 0.5.0 x86_64-linux-gnu，DataFrames 0.8.5，hcat和vcat上遇到了这个问题。

清除工作区和重新加载DataFrames都没有解决问题，但重新启动REPL会立即修复它。