不能使用条件语句将 append 列值添加到列表中

Question

I have a dataframe

import pandas as pd
df = pd.DataFrame({'product':['shoe','shirt','pants','socks'],
                   'review_rating':[1.2,3.0,4.0,2.1],
                   'review_text':['good','bad','good','bad']})
good_reviews = []
print(df)

I want to be able to append my review_text values to the list using a conditional statement.

I tried this:

for column in df[['reviews.rating', 'reviews.text']]:
    if df[df['reviews.rating']] <= 2.0:
        good_reviews.append(df['reviews.text'])

After trying that I got an error:

KeyError: None of [Index(['reviews.rating', 'reviews.text'], dtype='object')] are in the [columns]

Answer 1

import pandas as pd
df = pd.DataFrame({'product':['shoe','shirt','pants','socks'],
                   'review_rating':[1.2,3.0,4.0,2.1],
                   'review_text':['good','bad','good','bad']})

good_reviews = df.loc[df["review_rating"] <= 2.0,'review_text']

print(good_review)

Answer 2

You get that error because the column names in your loop are not the same as those in df .

Now about your particular problem, you can create a boolean mask and use it to filter review_text .

boolean_mask = df['review_rating']<=2
ratings = df.loc[boolean_mask,'review_text']

and if you already have the good_reviews list, you can extend that list by:

good_reviews.extend(ratings.tolist())