我想找出我的数据的每一列中NaN的数量。
当前回答
希望这能有所帮助,
import pandas as pd
import numpy as np
df = pd.DataFrame({'a':[1,2,np.nan], 'b':[np.nan,1,np.nan],'c':[np.nan,2,np.nan], 'd':[np.nan,np.nan,np.nan]})
df.isnull().sum()/len(df) * 100
Thres = 40
(df.isnull().sum()/len(df) * 100 ) < Thres
其他回答
import numpy as np
import pandas as pd
raw_data = {'first_name': ['Jason', np.nan, 'Tina', 'Jake', 'Amy'],
'last_name': ['Miller', np.nan, np.nan, 'Milner', 'Cooze'],
'age': [22, np.nan, 23, 24, 25],
'sex': ['m', np.nan, 'f', 'm', 'f'],
'Test1_Score': [4, np.nan, 0, 0, 0],
'Test2_Score': [25, np.nan, np.nan, 0, 0]}
results = pd.DataFrame(raw_data, columns = ['first_name', 'last_name', 'age', 'sex', 'Test1_Score', 'Test2_Score'])
results
'''
first_name last_name age sex Test1_Score Test2_Score
0 Jason Miller 22.0 m 4.0 25.0
1 NaN NaN NaN NaN NaN NaN
2 Tina NaN 23.0 f 0.0 NaN
3 Jake Milner 24.0 m 0.0 0.0
4 Amy Cooze 25.0 f 0.0 0.0
'''
您可以使用以下函数,它将在Dataframe中提供输出
零值 缺失值 占总额的% 总零缺失值 总零缺失值% 数据类型
只需复制和粘贴下面的函数,并通过传递你的熊猫数据帧来调用它
def missing_zero_values_table(df):
zero_val = (df == 0.00).astype(int).sum(axis=0)
mis_val = df.isnull().sum()
mis_val_percent = 100 * df.isnull().sum() / len(df)
mz_table = pd.concat([zero_val, mis_val, mis_val_percent], axis=1)
mz_table = mz_table.rename(
columns = {0 : 'Zero Values', 1 : 'Missing Values', 2 : '% of Total Values'})
mz_table['Total Zero Missing Values'] = mz_table['Zero Values'] + mz_table['Missing Values']
mz_table['% Total Zero Missing Values'] = 100 * mz_table['Total Zero Missing Values'] / len(df)
mz_table['Data Type'] = df.dtypes
mz_table = mz_table[
mz_table.iloc[:,1] != 0].sort_values(
'% of Total Values', ascending=False).round(1)
print ("Your selected dataframe has " + str(df.shape[1]) + " columns and " + str(df.shape[0]) + " Rows.\n"
"There are " + str(mz_table.shape[0]) +
" columns that have missing values.")
# mz_table.to_excel('D:/sampledata/missing_and_zero_values.xlsx', freeze_panes=(1,0), index = False)
return mz_table
missing_zero_values_table(results)
输出
Your selected dataframe has 6 columns and 5 Rows.
There are 6 columns that have missing values.
Zero Values Missing Values % of Total Values Total Zero Missing Values % Total Zero Missing Values Data Type
last_name 0 2 40.0 2 40.0 object
Test2_Score 2 2 40.0 4 80.0 float64
first_name 0 1 20.0 1 20.0 object
age 0 1 20.0 1 20.0 float64
sex 0 1 20.0 1 20.0 object
Test1_Score 3 1 20.0 4 80.0 float64
如果你想保持简单,那么你可以使用下面的函数来获取%中缺失的值
def missing(dff):
print (round((dff.isnull().sum() * 100/ len(dff)),2).sort_values(ascending=False))
missing(results)
'''
Test2_Score 40.0
last_name 40.0
Test1_Score 20.0
sex 20.0
age 20.0
first_name 20.0
dtype: float64
'''
另一种完整的方法是使用np。带有.isna()的count_non0:
np.count_nonzero(df.isna())
%timeit np.count_nonzero(df.isna())
512 ms ± 24.7 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
使用1000005行× 16列的数据框架与顶部答案进行比较:
%timeit df.isna().sum()
492 ms ± 55.2 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
%timeit df.isnull().sum(axis = 0)
478 ms ± 34.9 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
%timeit count_nan = len(df) - df.count()
484 ms ± 47.4 ms per loop (mean ± std. dev. of 7 runs, 1 loop each)
数据:
raw_data = {'first_name': ['Jason', np.nan, 'Tina', 'Jake', 'Amy'],
'last_name': ['Miller', np.nan, np.nan, 'Milner', 'Cooze'],
'age': [22, np.nan, 23, 24, 25],
'sex': ['m', np.nan, 'f', 'm', 'f'],
'Test1_Score': [4, np.nan, 0, 0, 0],
'Test2_Score': [25, np.nan, np.nan, 0, 0]}
results = pd.DataFrame(raw_data, columns = ['first_name', 'last_name', 'age', 'sex', 'Test1_Score', 'Test2_Score'])
# big dataframe for %timeit
big_df = pd.DataFrame(np.random.randint(0, 100, size=(1000000, 10)), columns=list('ABCDEFGHIJ'))
df = pd.concat([big_df,results]) # 1000005 rows × 16 columns
我使用这个循环来计算每一列的缺失值:
# check missing values
import numpy as np, pandas as pd
for col in df:
print(col +': '+ np.str(df[col].isna().sum()))
如果你正在使用Jupyter笔记本,如何....
%%timeit
df.isnull().any().any()
or
%timeit
df.isnull().values.sum()
或者,数据中是否存在nan,如果有,在哪里?
df.isnull().any()
df.isnull().sum()
//type: <class 'pandas.core.series.Series'>
or
df.column_name.isnull().sum()
//type: <type 'numpy.int64'>
推荐文章
- Visual Studio Code:如何调试Python脚本的参数
- 使用元组/列表等等。从输入vs直接引用类型如list/tuple/etc
- 结合conda环境。Yml和PIP requirements.txt
- 将命名元组转换为字典
- 如何使x轴和y轴的刻度相等呢?
- Numpy在这里函数多个条件
- 在Python中,使用argparse只允许正整数
- 如何排序mongodb与pymongo
- 不可变与可变类型
- 列表是线程安全的吗?
- 操作系统。makdirs在我的路径上不理解“~”
- 如何在Django模板中获得我的网站的域名?
- 在django Forms中定义css类
- 如何在Python中scp ?
- Numpy Max vs amax vs maximum