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[英]Comparing values of a single column of pandas dataframe in python (transforming perl to python code)
[英]Comparing dataframe column with single value in pandas python
我使用輸入的SQL查詢在python上構建了數據框架。 之后,我為列命名,並確保用NaN值隔離列是很好的:
cursor.execute(raw_input("Enter your SQL query: "))
records = cursor.fetchall()
import pandas as pd
dframesql = pd.DataFrame(records)
dframesql.columns = [i[0] for i in cursor.description]
當我想將數據行的數量與數據幀中的總行數進行比較時,就會出現問題:
dframelines = len(dframesql)
dframedesc = pd.DataFrame(dframesql.count())
當我嘗試將dframedesc與dframelines比較時,出現錯誤
nancol = []
for line in dframedesc:
if dframedesc < dframelines:
nancol.append(line)
ValueError: The truth value of a DataFrame is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
提前致謝 !
如果要使用forloop進行操作,請遍歷df的索引:
nancol = []
for index in dframedesc.index:
if dframedesc.loc[index,'a_column'] < dframelines:
nancol.append(dframedesc.loc[index,:])
但是為什么不只是:
dframedesc[dframedesc['col_to_compare'] < dframelines]
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