從字典列表建立 Pandas DataFrame

Luqman Khan 2022年5月16日
從字典列表建立 Pandas DataFrame

字典是一個緊湊而靈活的 Python 容器,用於儲存單獨的鍵值對映。字典用大括號 ({}) 編寫,其中包括用逗號 (,): 分隔每個鍵與其值的關鍵字對。

下面顯示了三個字典,其中包含一個骰子游戲的示例。

讓我們以骰子游戲為例。在這種情況下,兩名玩家滾動他們的六個骰子並與相應的玩家儲存骰子。

import pandas as pd
from numpy.random import randint
# create datset from multiple dictionaries
dataset_list=[{'Harry':1,'Josh':3,'dices':'first dice'},
              {'Harry':5,'Josh':1,'dices':'second dice'},
              {'Harry':6,'Josh':2,'dices':'third dice'},
              {'Harry':2,'Josh':3,'dices':'fourth dice'},
              {'Harry':6,'Josh':6,'dices':'fifth dice'},
              {'Harry':4,'Josh':3,'dices':'sixth dice'}]

df=pd.DataFrame(dataset_list)
print(df)
print()
harry=[]
josh=[]
for i in range(6):
    harry.append(randint(1,7))
    josh.append(randint(1,7))

我們從包含字典的專案列表中建立了一個資料集,因為我們知道 DataFrame 採用鍵值對。這就是為什麼這適用於字典。

輸出:

   Harry  Josh        dices
0      1     3   first dice
1      5     1  second dice
2      6     2   third dice
3      2     3  fourth dice
4      6     6   fifth dice
5      4     3   sixth dice

我們在上一個例子中手動設定骰子;現在,我們將使用 numpy 庫中定義的 randint 方法。我們在下一行建立了兩個名為 harryjosh 的空白列表。接下來,我們建立了一個 for 迴圈,該範圍定義為 0-6,使用 append() 方法將兩個已定義列表中的隨機數作為元素附加,如下所示。

import pandas as pd
from numpy.random import randint
print()
harry=[]
josh=[]
for i in range(6):
    harry.append(randint(1,7))
    josh.append(randint(1,7))
# create datset from multiple dictionaries
dataset_list=[{'Harry':harry[0],'Josh':josh[0],'dices':'first dice'},
              {'Harry':harry[1],'Josh':josh[1],'dices':'second dice'},
              {'Harry':harry[2],'Josh':josh[2],'dices':'third dice'},
              {'Harry':harry[3],'Josh':josh[3],'dices':'fourth dice'},
              {'Harry':harry[4],'Josh':josh[4],'dices':'fifth dice'},
              {'Harry':harry[5],'Josh':josh[5],'dices':'sixth dice'}]

df=pd.DataFrame(dataset_list)
print(df)

請記住,randint() 的範圍從給定的 1 到 n-1,或者預設情況下從零到 n-1,這就是我們定義從 1-7 的範圍的原因。

輸出

   Harry  Josh        dices
0      4     1   first dice
1      4     2  second dice
2      3     4   third dice
3      1     1  fourth dice
4      4     5   fifth dice
5      4     4   sixth dice

現在我們在 for 迴圈的幫助下減少了程式碼行,並將整個字典附加到一個列表中,進一步在名為 index 的列表中附加索引與玩家回合相對應並設定為 DataFrame 中的索引。

import pandas as pd
from numpy.random import randint
dataset_list=[]
index=[]
for i in range(1,7):
    dataset_list.append({'Harry':randint(1,7),'Josh':randint(1,7)})
    index.append('dice '+str(i))
print('\nAfter reducing the code\n')
df=pd.DataFrame(dataset_list,index=index)

print(df)

輸出:

        Harry  Josh
dice 1      2     4
dice 2      2     3
dice 3      6     5
dice 4      5     2
dice 5      4     2
dice 6      1     1

所有示例:

import pandas as pd
from numpy.random import randint
# create datset from multiple dictionaries
dataset_list=[{'Harry':1,'Josh':3,'dices':'first dice'},
              {'Harry':5,'Josh':1,'dices':'second dice'},
              {'Harry':6,'Josh':2,'dices':'third dice'},
              {'Harry':2,'Josh':3,'dices':'fourth dice'},
              {'Harry':6,'Josh':6,'dices':'fifth dice'},
              {'Harry':4,'Josh':3,'dices':'sixth dice'}]

df=pd.DataFrame(dataset_list)
print(df)
print()
harry=[]
josh=[]
for i in range(6):
    harry.append(randint(1,7))
    josh.append(randint(1,7))

# create datset from multiple dictionaries
dataset_list=[{'Harry':harry[0],'Josh':josh[0],'dices':'first dice'},
              {'Harry':harry[1],'Josh':josh[1],'dices':'second dice'},
              {'Harry':harry[2],'Josh':josh[2],'dices':'third dice'},
              {'Harry':harry[3],'Josh':josh[3],'dices':'fourth dice'},
              {'Harry':harry[4],'Josh':josh[4],'dices':'fifth dice'},
              {'Harry':harry[5],'Josh':josh[5],'dices':'sixth dice'}]

df=pd.DataFrame(dataset_list)
print(df)

dataset_list=[]
index=[]
for i in range(1,7):
    dataset_list.append({'Harry':randint(1,7),'Josh':randint(1,7)})
    index.append('dice '+str(i))
print('\nAfter reducing the code\n')
df=pd.DataFrame(dataset_list,index=index)

print(df)

輸出:

   Harry  Josh        dices
0      1     3   first dice
1      5     1  second dice
2      6     2   third dice
3      2     3  fourth dice
4      6     6   fifth dice
5      4     3   sixth dice

   Harry  Josh        dices
0      4     1   first dice
1      4     2  second dice
2      3     4   third dice
3      1     1  fourth dice
4      4     5   fifth dice
5      4     4   sixth dice

After reducing the code

        Harry  Josh
dice 1      2     4
dice 2      2     3
dice 3      6     5
dice 4      5     2
dice 5      4     2
dice 6      1     1