This question already has an answer here:
Reversing the order of values in a single column of a Dataframe
(1 answer)
Closed 1 year ago.
I need to reverse a series for correct plotting.
So I wrote the code below:
dataFrame["close"] = dataFrame["close"][::-1]
But it doesn't differ. Why?
You are including the specific column. You should reverse the entire dataframe like this:
dataFrame.reindex(index=dataFrame.index[::-1])
or
dataFrame.iloc[::-1]
Related
This question already has answers here:
How do I transpose dataframe in pandas without index?
(3 answers)
Closed 11 months ago.
I am trying to analyze chines GDP according to its provinces. I want to make a line chart that shows changing GDP over time but I cannot group them.
i want to pivot the table but it is not working as I want.
but I want to make it like this
It looks like you want to switch x and y axes. Use transpose. You can call it with T.
transposed_df = df_data.T
print(transposed_df)
This question already has answers here:
pyspark: grouby and then get max value of each group
(2 answers)
Closed 1 year ago.
I have such a DF. I am working on tables in the form of rdd
I would like to get a table with the maximum order value for a given country and the customer number for this customer.
I have no idea how to construct the map function. Unless there is a better way?
With PySpark:
df.groupBy('customernumber', 'city').max('sum_of_orders')
With Pandas:
df.groupby(['customernumber', 'city'])['sum_of_orders'].max()
This question already has answers here:
The first three max value in a column in python
(1 answer)
Count and Sort with Pandas
(5 answers)
Closed 3 years ago.
I am doing an online course which has a problem like " Find the name of the state with maximum number of counties". The problem dataframe is the image below
Problem Dataframe
Now, I have given the dataframe two new index (hierarchical indexing) and after that the dataframe takes a new look like the image below
Modified Dataframe
I have used this code to get the modified dataframe:
def answer_five():
new_df = census_df[census_df['SUMLEV'] == 50]
new_df = new_df.set_index(['STNAME', 'CTYNAME'])
return new_df
answer_five()
What I want to do now is to find the name of the state with most number of counties i.e to find the index with maximum number of rows. How Can I do that?
I know that using something like groupby() method this can be done but I'm not familiar with this method yet and so don't want to use it. Can anyone help? I have searched for this but failed. Sorry if the problem is rudimentary. Thanks in advance.
This question already has answers here:
Pandas groupby: How to get a union of strings
(8 answers)
Closed 3 years ago.
new in pandas and I was able to create a dataframe from a csv file. I was also able to sort it out.
What I am struggling now is the following: I give an image as an example from a pandas data frame.
First column is the index,
Second column is a group number
Third column is what happened.
I want based on the second column to take out the third column on the same unique data frame.
I highlight few examples: For the number 9 return back the sequence
[60,61,70,51]
For the number 6 get back the sequence
[65,55,56]
For the number 8 get back the single element 8.
How groupby can be used to do this extraction?
Thanks a lot
Regards
Alex
Starting from the answers on this question we can extract following code to receive the desired result.
dataframe = pd.DataFrame({'index':[0,1,2,3,4], 'groupNumber':[9,9,9,9,9], 'value':[12,13,14,15,16]})
grouped = dataframe.groupby('groupNumber')['value'].apply(list)
This question already has answers here:
Find the list values not in pandas dataframe data
(3 answers)
Closed 5 years ago.
I have a data frame and I need to get the rows which are "no in" the given list
I know in order to get the rows from the list we can use isin.(list), so my question is whether there is a contrary "notin" function?
You can use the ~ in front of condition to negate it.
~df['Col1'].isin(list)
df['Col1'].isin(list) will return True/False, then just flip the boolean to get True where Col1 is not in the list.