I am trying to color points of a pandas dataframe depending on TWO conditions. Example: I have tried so many different ways now and everything I found online was only depending on one condition. My example code always raises the Error: Here’s the code. Tried several variations without success. Btw: I un…
Tag: numpy
Attribute error while using opencv for face recognition
I am teaching myself how to use openCV by writing a simple face recognition program I found on youtube. I have installed opencv version 2 as well as numpy 1.8.0. I am using python 2.7. I copyed this code exactly how it was done in the video and article links below, yet I keep getting errors. AttributeError: &…
Why does fftfreq produce negative values?
From the documentation for fftfreq: Why are there negative values in the output array? I am trying to produce a plot of amplitude vs frequency. I can get the amplitude by running the abs() function over the elements of fourier, but how do I convert freq into a series of frequencies that I can use as an x-axis…
Dealing with masked coordinate arrays in pcolormesh
I’m working on visualizing some climate model output. The computation is done on a projected latitude/longitude grid. Since the model is simulating sea ice, all land grid cells are masked. The standard tools for plotting geographical information in Python are Basemap and Cartopy, both of which use matpl…
python how to pad numpy array with zeros
I want to know how I can pad a 2D numpy array with zeros using python 2.6.6 with numpy version 1.5.0. But these are my limitations. Therefore I cannot use np.pad. For example, I want to pad a with zeros such that its shape matches b. The reason why I want to do this is so I can do: such
How can a string representation of a NumPy array be converted to a NumPy array?
The function numpy.array_repr can be used to create a string representation of a NumPy array. How can a string representation of a NumPy array be converted to a NumPy array? Let’s say the string representation is as follows: How could this be converted to a NumPy array? Answer eval is the easiest, proba…
How to use sklearn fit_transform with pandas and return dataframe instead of numpy array?
I want to apply scaling (using StandardScaler() from sklearn.preprocessing) to a pandas dataframe. The following code returns a numpy array, so I lose all the column names and indeces. This is not what I want. A “solution” I found online is: It appears to work, but leads to a deprecationwarning: /…
Type hinting / annotation (PEP 484) for numpy.ndarray
Has anyone implemented type hinting for the specific numpy.ndarray class? Right now, I’m using typing.Any, but it would be nice to have something more specific. For instance if the NumPy people added a type alias for their array_like object class. Better yet, implement support at the dtype level, so tha…
‘numpy.ndarray’ object has no attribute ‘find’ while trying to generate boxplot?
I am trying to generate a box plot. Here is my code, data below: The data is float which is verified by the print command as its output is <type ‘float’>. On running the code, I am getting the following error (full stacktrace below) AttributeError: ‘numpy.ndarray’ object has no a…
Concat DataFrame Reindexing only valid with uniquely valued Index objects
I am trying to concat the following dataframes: df1 and: df2 With But I get the follwing output: I have removed additional columns and removed duplicates and NA where there could be a conflict – but I simply do not know what’s wrong. Answer pd.concat requires that the indices be unique. To remove …