I am attempting to remove all non-numeric characters from my dataframe (ie characters like ]$^M# etc.) with a single line of code. The data frame is a Google Play Store apps dataset.
df = pd.read_csv("googleplaystore.csv")
df['Rating'].fillna(value = '0.0', inplace = True)
#sample data#
Rating Reviews Size Installs Type Price \
0 4.1 159 19M 10,000+ Free 0
1 3.9 967 14M 500,000+ Free 0
2 4.7 87510 8.7M 5,000,000+ Free 0
3 4.5 215644 25M 50,000,000+ Free 0
4 4.3 967 2.8M 100,000+ Free 0
... ... ... ... ... ... ...
10836 4.5 38 53M 5,000+ Free 0
10837 5 4 3.6M 100+ Free 0
10838 0.0 3 9.5M 1,000+ Free 0
10839 4.5 114 Varies with device 1,000+ Free 0
10840 4.5 398307 19M 10,000,000+ Free 0
Content Rating Genres Last Updated \
0 Everyone Art & Design January 7, 2018
1 Everyone Art & Design;Pretend Play January 15, 2018
2 Everyone Art & Design August 1, 2018
3 Teen Art & Design June 8, 2018
4 Everyone Art & Design;Creativity June 20, 2018
... ... ... ...
10836 Everyone Education July 25, 2017
10837 Everyone Education July 6, 2018
10838 Everyone Medical January 20, 2017
10839 Mature 17+ Books & Reference January 19, 2015
10840 Everyone Lifestyle July 25, 2018
clean_data = df.replace('[^\d.]', '', regex = True).astype(float)
Essentially I am trying to remove the 'M' from the Size column after the digits as well as the '+' sign in the Installs column.
But I'm returned with this error message;
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
<ipython-input-325-887d47a9889e> in <module>
----> 1 data_ = df.replace('[^\d.]', '', regex = True).astype(float)
~\anaconda3\lib\site-packages\pandas\core\generic.py in astype(self, dtype, copy, errors)
5696 else:
5697 # else, only a single dtype is given
-> 5698 new_data = self._data.astype(dtype=dtype, copy=copy, errors=errors)
5699 return self._constructor(new_data).__finalize__(self)
5700
~\anaconda3\lib\site-packages\pandas\core\internals\managers.py in astype(self, dtype, copy, errors)
580
581 def astype(self, dtype, copy: bool = False, errors: str = "raise"):
--> 582 return self.apply("astype", dtype=dtype, copy=copy, errors=errors)
583
584 def convert(self, **kwargs):
~\anaconda3\lib\site-packages\pandas\core\internals\managers.py in apply(self, f, filter, **kwargs)
440 applied = b.apply(f, **kwargs)
441 else:
--> 442 applied = getattr(b, f)(**kwargs)
443 result_blocks = _extend_blocks(applied, result_blocks)
444
~\anaconda3\lib\site-packages\pandas\core\internals\blocks.py in astype(self, dtype, copy, errors)
623 vals1d = values.ravel()
624 try:
--> 625 values = astype_nansafe(vals1d, dtype, copy=True)
626 except (ValueError, TypeError):
627 # e.g. astype_nansafe can fail on object-dtype of strings
~\anaconda3\lib\site-packages\pandas\core\dtypes\cast.py in astype_nansafe(arr, dtype, copy, skipna)
895 if copy or is_object_dtype(arr) or is_object_dtype(dtype):
896 # Explicit copy, or required since NumPy can't view from / to object.
--> 897 return arr.astype(dtype, copy=True)
898
899 return arr.view(dtype)
ValueError: could not convert string to float:
Kindly assist in debugging if possible. I would really like to keep it to one line of code for the entire data frame. Thank you in advance.
I think problem is need specify columns for replace and replace empty value to NaN
or 0
if not numeric like second last Size
value:
cols = ['Size','Installs']
df[cols] = df[cols].replace('[^\d.]', '', regex = True).replace('',np.nan).astype(float)
print (df)
Rating Reviews Size Installs Type Price
0 4.1 159 19.0 10000.0 Free 0
1 3.9 967 14.0 500000.0 Free 0
2 4.7 87510 8.7 5000000.0 Free 0
3 4.5 215644 25.0 50000000.0 Free 0
4 4.3 967 2.8 100000.0 Free 0
10836 4.5 38 53.0 5000.0 Free 0
10837 5.0 4 3.6 100.0 Free 0
10838 0.0 3 9.5 1000.0 Free 0
10839 4.5 114 NaN 1000.0 Free 0
10840 4.5 398307 19.0 10000000.0 Free 0
The problem is that you are replacing all non-numeric characters in your dataframe with "".
This means that a non-numeric string ends up as "" - a zero-length string. That can't be interpreted as a float, so you get the error.
If you run the replace over just your rating column
df["Rating"].replace('[^\d.]', '', regex = True).astype(float)
then it works, because removing non-numeric characters from that column results in a column filled only with characters that can be converted into numbers.
However, running it over the whole dataframe doesn't work because so many of your values are purely non-numeric. The genre column, for example, will end up as just a column of empty strings, throwing the error.
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