SettingWithCopyWarning on Guided Project Stock Market Predictions

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#1

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My Code: 

test = sp[sp["Date"]>datetime(2013,1,1)]

training_columns=["5 Day Price Avg", "30 Day Price Avg", "365 Day Price Avg"]

reg = linear_model.LinearRegression()
reg.fit(train[training_columns], train[["Close"]])
predictions = reg.predict(test[training_columns])

test["Predictions"] = predictions```

What I expected to happen:

I expect to add a new column to the test data frame with the predicted close values.


What actually happened:

predict.py:32: SettingWithCopyWarning:
A value is trying to be set on a copy of a slice from a DataFrame.
Try using .loc[row_indexer,col_indexer] = value instead

See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
test[“Predictions”] = predictions

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1 Like
#2

Yeah, this is something that still confuses me and I never got around to understand the problem clearly.

Does using copy help to get rid of the warning?

test = sp[sp["Date"]>datetime(2013,1,1)].copy()

If I recall correctly, you should still be able to run the code because it’s just a warning and not an error. Though, depending on the circumstances, ignoring that warning might or might not be a good idea.

This guide by Dataquest might be more helpful than me: