nan

问题 I am using pandas read_sql_query to read data from a MySQL database table into a pandas dataframe. Some columns in this table have all NULL values. For those columns the pandas dataframe contains None in every row. For all other columns the dataframe contains NaN where there was a NULL value. Can anyone explain why None is returned for the all NULL columns? And how do I make sure I have all NaNs, hopefully without doing manual conversions? I should add that two of the columns causing this

问题 I have a data frame df like this df = pd.DataFrame([ {'Name': 'Chris', 'Item Purchased': 'Sponge', 'Cost': 22.50}, {'Name': 'Kevyn', 'Item Purchased': 'Kitty Litter', 'Cost': '.........'}, {'Name': 'Filip', 'Item Purchased': 'Spoon', 'Cost': '...'}], index=['Store 1', 'Store 1', 'Store 2']) I want to replace the missing values in 'Cost' columns to np.nan . So far I have tried: df['Cost']=df['Cost'].str.replace("\.\.+", np.nan) and df['Cost']=re.sub('\.\.+',np.nan,df['Cost']) but neither of

问题 I have a data frame df like this df = pd.DataFrame([ {'Name': 'Chris', 'Item Purchased': 'Sponge', 'Cost': 22.50}, {'Name': 'Kevyn', 'Item Purchased': 'Kitty Litter', 'Cost': '.........'}, {'Name': 'Filip', 'Item Purchased': 'Spoon', 'Cost': '...'}], index=['Store 1', 'Store 1', 'Store 2']) I want to replace the missing values in 'Cost' columns to np.nan . So far I have tried: df['Cost']=df['Cost'].str.replace("\.\.+", np.nan) and df['Cost']=re.sub('\.\.+',np.nan,df['Cost']) but neither of

问题 I have a data frame df like this df = pd.DataFrame([ {'Name': 'Chris', 'Item Purchased': 'Sponge', 'Cost': 22.50}, {'Name': 'Kevyn', 'Item Purchased': 'Kitty Litter', 'Cost': '.........'}, {'Name': 'Filip', 'Item Purchased': 'Spoon', 'Cost': '...'}], index=['Store 1', 'Store 1', 'Store 2']) I want to replace the missing values in 'Cost' columns to np.nan . So far I have tried: df['Cost']=df['Cost'].str.replace("\.\.+", np.nan) and df['Cost']=re.sub('\.\.+',np.nan,df['Cost']) but neither of

问题 I have a data frame df like this df = pd.DataFrame([ {'Name': 'Chris', 'Item Purchased': 'Sponge', 'Cost': 22.50}, {'Name': 'Kevyn', 'Item Purchased': 'Kitty Litter', 'Cost': '.........'}, {'Name': 'Filip', 'Item Purchased': 'Spoon', 'Cost': '...'}], index=['Store 1', 'Store 1', 'Store 2']) I want to replace the missing values in 'Cost' columns to np.nan . So far I have tried: df['Cost']=df['Cost'].str.replace("\.\.+", np.nan) and df['Cost']=re.sub('\.\.+',np.nan,df['Cost']) but neither of

问题 I have a dataframe which contains nan values at few places. I am trying to perform data cleaning in which I fill the nan values with mean of it's previous five instances. To do so, I have come up with the following. input_data_frame[var_list].fillna(input_data_frame[var_list].rolling(5).mean(), inplace=True) But, this is not working. It isn't filling the nan values. There is no change in the dataframe's null count before and after the above operation. Assuming I have a dataframe with just

问题 [1, 2, 3].indexOf(3) => 2 [1, 2, NaN].indexOf(NaN) => -1 [1, NaN, 3].indexOf(NaN) => -1 回答1: You can use Array.prototype.findIndex method to find out the index of NaN in an array let index = [1,3,4,'hello',NaN,3].findIndex(Number.isNaN) console.log(index) You can use Array.prototype.includes to check if NaN is present in an array or not. It won't give you the index though !! It will return a boolean value. If NaN is present true will be returned, otherwise false will be returned let

问题 [1, 2, 3].indexOf(3) => 2 [1, 2, NaN].indexOf(NaN) => -1 [1, NaN, 3].indexOf(NaN) => -1 回答1: You can use Array.prototype.findIndex method to find out the index of NaN in an array let index = [1,3,4,'hello',NaN,3].findIndex(Number.isNaN) console.log(index) You can use Array.prototype.includes to check if NaN is present in an array or not. It won't give you the index though !! It will return a boolean value. If NaN is present true will be returned, otherwise false will be returned let

来源： https://stackoverflow.com/questions/28182982/check-nan-values-java

来源： https://stackoverflow.com/questions/28182982/check-nan-values-java