Guided Project: Storytelling Data Visualization - SettingWithCopyWarning

Hello,

I am at the 4th instruction of the assignment. Where I have to remove all rows with a dash as an index value. I used the code below, which actually works.

https://app.dataquest.io/m/529/guided-project%3A-storytelling-data-visualization-on-exchange-rates/2/data-cleaning

My Code:

euro_to_dollar.drop(euro_to_dollar[euro_to_dollar["US_dollar"] == "-"].index, inplace = True) 
print(euro_to_dollar["US_dollar"].value_counts())

What I expected to happen:

I expected all index values with a dash to be removed from the dataframe. Although it worked, I am getting a SettingWithCopyWarning. So my question is whether it is wise to continue or should I adjust the code to avoid and if yes. How?

What actually happened:

/dataquest/system/env/python3/lib/python3.4/site-packages/ipykernel/__main__.py:3: SettingWithCopyWarning: 
A value is trying to be set on a copy of a slice from a DataFrame

See the caveats in the documentation: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-view-versus-copy
  app.launch_new_instance()

Show the code where you have assign or created euro_to_dollar variable dataframe.