/// <summary>
/// 切片
/// </summary>
/// <param name="s"></param>
/// <returns></returns>
public IDataFrame this[SliceLabel s]
{
get
{
List <object> objs = new List <object>();
List <TIndex> indexs = null;
if (_rawIndex != null)
{
indexs = new List <TIndex>();
}
NDArray nDArray = null;
//转换获取的标签行索引
int start = 0;
int end = int.MaxValue;
if (!string.IsNullOrEmpty(s.StartLabel))
{
start = Index.GetPosition(s.StartLabel);
}
if (!string.IsNullOrEmpty(s.EndLabel))
{
end = Index.GetPosition(s.EndLabel);
}
//验证长度
var lengthVail = Values.size / Values.shape[1] - 1;
var length = end;
if (end > lengthVail)
{
length = lengthVail;
}
//验证开始和结束位置
VailStartAndEnd(start, length, lengthVail);
bool desc = s.Step < 0;
//修正start和length,降序
if (desc)
{
int temp = start;
start = length - 1;
length = temp;
}
for (int i = start; Calc(i, length, desc, true); i += s.Step)
{
//获取下标
int index = GetIndex(i, lengthVail);
if (_rawIndex != null)
{
indexs.Add(_rawIndex[index]);
}
var value = Values[index] as NDArray;
objs.AddRange(value.Data <object>());
}
nDArray = np.array(objs.ToArray(), Values.dtype);
int ndim = Columns.Size;
nDArray.reshape(objs.Count / ndim, ndim);
var result = new DataFrame <TIndex>(nDArray, indexs, _rawColumns, _dtype);
return(result);
}
}
public void Create_implicit()
{
SliceLabel sliceLabel = "row1:row2:3";
Assert.Equal("row1", sliceLabel.StartLabel);
Assert.Equal("row2", sliceLabel.EndLabel);
Assert.Equal(3, sliceLabel.Step);
}