Question

我有一个函数myfunc，它在两个pandas DataFrame列上进行计算。输出是一个Numpy数组。

def myfunc(df, args):
    import numpy
    return numpy.array([df.iloc[:,args[0]].sum,df.iloc[:,args[1]].sum])

在rolling_df_apply中调用此函数：

def rolling_df_apply(df, myfunc, window, *args):
    import pandas
    result = pandas.concat(pandas.DataFrame(myfunc(df.iloc[i:window+i],args), index=[df.index[i+window-1]]) for i in xrange(0,len(df)-window+1))
    return result

通过

运行

import numpy
import pandas
df=pandas.DataFrame(numpy.random.randint(5,size=(5,2)))
window=3
args = [0,1]
result = rolling_df_apply(df, myfunc, window, *args)

在pandas.concat（）中给出ValueError：传递值的形状是（1,2），索引暗示（1,1）。为了让这个运行必须改变什么？哪个指数意味着形状1,1？但是要连接的所有数据帧的形状应该是1,2。

Answer 1

在myfunc .sum中，.sum()应为myfunc myfunc。

由于pandas.DataFrame(myfunc(df.iloc[i:window+i],args), index=[df.index[i+window-1]])返回长度为2的数组，

pd.DataFrame([0,1], index=[0])

与

基本相同

ValueError: Shape of passed values is (1, 2), indices imply (1, 1)

提出

[0,1]

错误是说值In [191]: pd.DataFrame({'a':0,'b':1}, index=[0]) Out[191]: a b 0 0 1意味着1行和2列，而索引意味着1行和1列。

解决这个问题的方法是传递一个dict而不是一个列表：

import pandas as pd
import numpy as np

def myfunc(df, args):
    return {'a':df.iloc[:,args[0]].sum(), 'b':df.iloc[:,args[1]].sum()}

def rolling_df_apply(df, myfunc, window, *args):

    frames = [pd.DataFrame(myfunc(df.iloc[i:window+i],args), 
                           index=[df.index[i+window-1]]) 
              for i in xrange(0,len(df)-window+1)]
    result = pd.concat(frames)
    return result

np.random.seed(2015)
df = pd.DataFrame(np.random.randint(5,size=(5,2)))
window=3
args = [0,1]

result = rolling_df_apply(df, myfunc, window, *args)   
print(result)

因此，要以最小的更改来修复代码，

产量

myfunc

然而，通过调用rolling_df_apply来替换pd.rolling_sum和result = pd.rolling_sum(df, window=3).dropna(axis=0)会更有效：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        const string FILENAME = @"c:\temp\test.txt";
        static void Main(string[] args)
        {
            field f = new field()
            {
                fields = new List<Person>() {
                    new Person() {
                        cid = "abc",
                        field_type = "def",
                        label = "ghi",
                        required = "true",
                        field_options = new List<sizee>() {
                            new sizee() {
                                size = "AAA",
                                options = new List<option>() {
                                    new option() {
                                        checke = "123",
                                        label = "456",
                                    },
                                   new option() {
                                        checke = "789",
                                        label = "012",
                                    }
                                }
                            },
                           new sizee() {
                                size = "BBB",
                                options = new List<option>() {
                                    new option() {
                                        checke = "321",
                                        label = "654",
                                    },
                                   new option() {
                                        checke = "987",
                                        label = "210",
                                    }
                                }
                            }
                        }
                    },
                   new Person() {
                        cid = "xyz",
                        field_type = "def",
                        label = "ghi",
                        required = "true",
                        field_options = new List<sizee>() {
                            new sizee() {
                                size = "AAA",
                                options = new List<option>() {
                                    new option() {
                                        checke = "123",
                                        label = "456",
                                    },
                                   new option() {
                                        checke = "789",
                                        label = "012",
                                    }
                                }
                            },
                           new sizee() {
                                size = "BBB",
                                options = new List<option>() {
                                    new option() {
                                        checke = "321",
                                        label = "654",
                                    },
                                   new option() {
                                        checke = "987",
                                        label = "210",
                                    }
                                }
                            }
                        }
                    }
                }
            };

            DataContractJsonSerializer ser = new DataContractJsonSerializer(typeof(field));
            FileStream stream = File.OpenWrite(FILENAME);
            ser.WriteObject(stream, f);

            stream.Flush();
            stream.Close();
            stream.Dispose();

        }
    }



    [DataContract]
    public class field
    {
        [DataMember]
        public List<Person> fields { get; set; }
    }

    [DataContract]
    public class Person
    {
        [DataMember]
        public string label { get; set; }
        [DataMember]
        public string field_type { get; set; }
        [DataMember]
        public string required { get; set; }
        [DataMember]
        public string cid { get; set; }
        [DataMember]
        public List<sizee> field_options { get; set; }
    }

    [DataContract]
    public class sizee
    {
        [DataMember]
        public string size { get; set; }
        [DataMember]
        public List<option> options { get; set; }
    }

    [DataContract]
    public class option
    {
        [DataMember]
        public string checke { get; set; }
        [DataMember]
        public string label { get; set; }
    }
}

产生相同的结果。

在Dataframe上滚动窗口，多列输入和输出

1 个答案: