将Dataframe转换为dict列表太慢[重复]

Question

from pandas import DataFrame
import time

data = []
for i in range(3000):
    data.append(['SH601318', 'abcdef', 0.0001215, 0.000215, 0.125, 0.243])
df = DataFrame(data)
df.columns = ['symbol', 'name', 'total_ratio', 'outstanding_ratio', 'avg_total_ratio', 'avg_outstanding_ratio']

t = time.time()
result = [{
    'symbol': df.at[i, 'symbol'],
    'name': df.at[i, 'name'],
    'total_ratio': df.at[i, 'total_ratio'],
    'outstanding_ratio': df.at[i, 'outstanding_ratio'],
    'avg_total_ratio': df.at[i, 'avg_total_ratio'],
    'avg_outstanding_ratio': df.at[i, 'avg_outstanding_ratio'],
} for i in range(len(df))]
print '%.2f seconds' % (time.time() - t)
# 0.25 seconds

t = time.time()
result = [df.iloc[i].to_dict() for i in range(len(df))]
print '%.2f seconds' % (time.time() - t)
# 0.58 seconds

我尝试了 2 种方法将 DataFrame 转换为 dict 列表。但两者都很慢，250 毫秒和 580 毫秒！这远远超过我从数据库查询的时间。不知道为什么要花这么多时间，毕竟操作内存比磁盘快。我预计这个时间是 10 毫秒。有什么办法可以实现吗？

Answer 1

我认为你需要to_dict 和参数orient='records'：

print (df.to_dict(orient='records'))