Python+Arcpy操作Points（.shp）转换至Polyline（.shp），仔细研读Points To Line (Data Management)说明，参数说明如下：
Input_Features: The point features to be converted into lines.
Output_Feature_Class:The line feature class which will be created from the input points.
以下参数对生成闭合Polyline尤为重要（Optional）
Line_Field: Each feature in the output will be based on unique values in the Line Field.这里指出同一直线的各点应在某一Field下具有相同的数值，见图 1红框之内在Line1字段之下数值均为1，表示各点均在同一条Polyline。
图 1
Sort_Field: By default, points used to create each output line feature will be used in the order they are found. If a different order is desired, specify a Sort Field.
Close_Line: Specifies whether output line features should be closed. True or False.
举一个例子，从含有4points的.shp转换为1条闭合的Polyline（.shp）文件，转换输出如图 2，
图 2
原文：http://www.cnblogs.com/arxive/p/5087243.html