Python，如何用列表填充空数据框

Question

我正在尝试编写代码以将某些列表之间的公共元素保存在矩阵中。示例：

包含所有列表的数据框：

ID	elements of the ID
G1	P1,P2,P3,P4
G2	P3,P5
G3	P1,P3,P5
G4	P6

我从一个以 G1、G2、G3、G4 作为列名和行名的空矩阵开始，单元格用 nan 填充，我想要获得的结果如下：

X	G1	G2	G3	G4
G1	P1,P2,P3,P4	P3	P1	None
G2	P3	P3,P5	P3,P5	None
G3	P1,P5	P3,P5	P1,P3,P5	None
G4	None	None	None	P6

这是我的代码：

import sys
import pandas as pd

def intersection(lst1, lst2):
    return [value for value in lst1 if value in lst2]

data = pd.read_csv(sys.argv[1], sep="\t")
p_mat = pd.read_csv(sys.argv[2], sep="\t", index_col=0)
c_mat = pd.read_csv(sys.argv[3], sep="\t", index_col=0)

#I need this since the elements of the second column once imported are seen as a single string instead of being lists
for i in range(0,len(data)):
    data['MP term list'][i] = data['MP term list'][i].split(",")


for i in p_mat:
    for j in p_mat.columns:
        r = intersection(data[data['MGI id'] == i]['MP term list'].values.tolist()[0],data[data['MGI id'] == j]['MP term list'].values.tolist()[0])
        if len(r)!=0:
            p_mat.at[i,j] = r
        else:
            p_mat.at[i, j] = None
        del(r)

目前我只能正确填充第一个单元格，然后在我尝试存储在单元格中的第一个非空结果时出现此错误：

ValueError: Must have equal len keys and value when setting with an iterable

我该如何解决？感谢大家的帮助

Answer 1

尝试使用十字 merge，设置 intersection 和 pivot：

df["elements"] = df["elements of the ID"].str.split(",").map(set)

cross = df[["ID", "elements"]].merge(df[["ID", "elements"]], how="cross")
cross["intersection"] = (cross.apply(lambda row: row["elements_x"].intersection(row["elements_y"]), axis=1)
                              .map(",".join)
                              .replace("",None)
                        )

output = cross.pivot("ID_x", "ID_y", "intersection").rename_axis(None, axis=1).rename_axis(None)

>>> output
             G1     G2        G3    G4
G1  P2,P1,P3,P4     P3     P1,P3  None
G2           P3  P3,P5     P3,P5  None
G3        P1,P3  P3,P5  P1,P3,P5  None
G4         None   None      None    P6

输入 df:

df = pd.DataFrame({"ID": [f"G{i+1}" for i in range(4)],
                   "elements of the ID": ["P1,P2,P3,P4", "P3,P5", "P1,P3,P5", "P6"]})

Answer 2

import pandas as pd
ID = ["G1","G2","G3","G4"]
Elements = [["P1","P2","P3","P4"],
            ["P3","P5"],
            ["P1","P3","P5"],
            ["P6"]]

df = pd.DataFrame(zip(ID,Elements),columns = ["ID","Elements"])
df1 = pd.DataFrame(columns = ID)
df1["ID"] = ID
for i in ID:
    for j in ID:
        if i == j:
            df1.loc[df1.ID == i,j] = df.loc[df.ID == i,"Elements"]
        else:
            df1 = df1.astype("object")
            df1.loc[df1.ID == i,j] = df1.loc[df1.ID == i,j].apply(
                lambda x : list(set(list(df.loc[df.ID == i,"Elements"])[0]) & set(list(df.loc[df.ID == j,"Elements"])[0])))

输出：

df1
Out[38]: 
                 G1        G2            G3    G4  ID
0  [P1, P2, P3, P4]      [P3]      [P1, P3]    []  G1
1              [P3]  [P3, P5]      [P5, P3]    []  G2
2          [P1, P3]  [P5, P3]  [P1, P3, P5]    []  G3
3                []        []            []  [P6]  G4

Python，如何用列表填充空数据框

Python, how to fill an empty dataframe with lists

python

intersection

matrix

pandas

输入 df: