Questions tagged [data.table]
The data.table tag has no usage guidance.
14
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17 views
Are there decisive leaders in programming with tabular data?
What are the most effective bread-and-butter in-memory open source tabular data frameworks today? I have been working with tabular data for years with an in-house solution that integrates with Excel ...
1
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0answers
180 views
Calculating % by Dividing Filtered Matrix Columns in MS Power BI
Given: A monthly percentage (%) metric has to be calculated from dividing a column ('Numerator') from one table by a column ('Denominator') from another table, both filtered by month, as given in an ...
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1answer
65 views
how to see in pandas the element of a csv table with many columns (>30) which the names of its columns is more than 10 character?
how to see in pandas the element of a csv table with many columns (>25) which the names of its columns is more than 10 character?
I have 5000 rows and 32 columns and the label of some columns are more ...
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0answers
42 views
Study resources for data manipulation interview questions
A colleague of mine is studying for tech roles, and they're asked to solve a consistent type of problem during the phone screenings: practicing manipulating data (sets, hash tables/dictionaries, ...
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4answers
24k views
How to Write Multiple Data Frames in an Excel Sheet
I have multiple data frames with same column names. I want to write them together to an excel sheet stacked vertically on top of each other. And between each, there will be a text occupying a row. ...
3
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2answers
603 views
Mean across every several rows in pandas
I have a table of features and labels where each row has a time stamp. Labels are categorical. They go in a batch where one label repeats several times. Batches with the same label do not have a ...
0
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1answer
40 views
Software for automated database processing
I faced a problem which I'd like to solve w/o any programming. And looking for a software to do this.
I have a dataset, for example: (brand-id, brand-name, product-class-name;)
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1
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2answers
861 views
Theoretical Question: Data.table vs Data.frame with Big Data
I know that I can read in a very large csv file much faster with fread using the data.table ...
3
votes
1answer
172 views
Look for previous date in dataframe that has certain column category in R
I have the following data frame:
...
2
votes
1answer
25 views
How to make smaller categories with factor character variables
I have this data set with consist of ISO3166 Alpha-2 codes for countries.
Example: DE, AD, AE etc
They are coded as factor variables in R and there are about 173 observations.
Now because there are ...
3
votes
4answers
2k views
rows to columns in data.table R (or Python)
This is something I can't achieve with the reshape2 library for R. I have the following data:
...
-1
votes
1answer
1k views
R: Calculations based on frequencies / grouped / aggregate data
I am trying to do simple calculations in R when no raw data but grouped data with frequencies is available only. This is the case when I have a large amount of records in a database, say a large SQL ...
21
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4answers
16k views
Is pandas now faster than data.table?
https://github.com/Rdatatable/data.table/wiki/Benchmarks-%3A-Grouping
The data.table benchmarks hasn't been updated since 2014. I heard somewhere that Pandas is ...
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0answers
34 views
Table function output and order of arguments
I have a silly question. Below is the output of a logistic regression analysis I did. I notice that when I switch the order of the arguments I put in the table function in R that it also switch the ...
