I am trying to calculate time-based aggregations in Pandas based on date values stored in a separate tables. The top of the first table table_a looks like this: Here is the code to create the table: The second table, table_b, looks like this: and the code to create it is: I want to be able to get the sum of
Tag: dataframe
Add a sequential counter column on groups to a pandas dataframe
I feel like there is a better way than this: To achieve this: Is there a way to do it that avoids the callback? Answer use cumcount(), see docs here If you want orderings starting at 1
How can I subclass a Pandas DataFrame?
Subclassing Pandas classes seems a common need, but I could not find references on the subject. (It seems that Pandas developers are still working on it: Easier subclassing #60.) There are some SO questions on the subject, but I am hoping that someone here can provide a more systematic account on the current …
What does axis in pandas mean?
Here is my code to generate a dataframe: then I got the dataframe: When I type the commmand : I got : According to the reference of pandas, axis=1 stands for columns and I expect the result of the command to be So here is my question: what does axis in pandas mean? Answer It specifies the axis along which
Add x and y labels to a pandas plot
Suppose I have the following code that plots something very simple using pandas: How do I easily set x and y-labels while preserving my ability to use specific colormaps? I noticed that the plot() wrapper for pandas DataFrames doesn’t take any parameters specific for that. Answer In Pandas version 1.10 …
Convert floats to ints in Pandas?
I’ve been working with data imported from a CSV. Pandas changed some columns to float, so now the numbers in these columns get displayed as floating points! However, I need them to be displayed as integers or without comma. Is there a way to convert them to integers or not display the comma? Answer To m…
Pandas dataframe get first row of each group
I have a pandas DataFrame like following: I want to group this by [“id”,”value”] and get the first row of each group: Expected outcome: I tried following, which only gives the first row of the DataFrame. Any help regarding this is appreciated. Answer If you need id as column: To get n …
Difference between map, applymap and apply methods in Pandas
Can you tell me when to use these vectorization methods with basic examples? I see that map is a Series method whereas the rest are DataFrame methods. I got confused about apply and applymap methods though. Why do we have two methods for applying a function to a DataFrame? Again, simple examples which illustr…
How to add pandas data to an existing csv file?
I want to know if it is possible to use the pandas to_csv() function to add a dataframe to an existing csv file. The csv file has the same structure as the loaded data. Answer You can specify a python write mode in the pandas to_csv function. For append it is ‘a’. In your case: The default mode is…
How can I map True/False to 1/0 in a Pandas DataFrame?
I have a column in python pandas DataFrame that has boolean True/False values, but for further calculations I need 1/0 representation. Is there a quick pandas/numpy way to do that? Answer A succinct way to convert a single column of boolean values to a column of integers 1 or 0: