Merge pull request #648 from realpython/polars-groupby

Polars group by

Author: brendaweles

polars-groupby/README.md

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+This download contains materials for the Real Python tutorial [How to Group Data Using Polars .group_by()](https://realpython.com/aggregating-and-grouping-data-in-polars-groupby/).
+
+You should create a new folder named aggregations on your computer and place each of these files inside it. You may also consider creating a [Python virtual environment](https://realpython.com/python-virtual-environments-a-primer/) within this folder.
+
+Your download bundle contains the following files:
+
+course.parquet           - This file contains all data from both `math.parquet` and `portuguese.parquet`.
+math.parquet             - This file contains data relating to a mathematics class.
+portuguese.parquet       - This file contains data relating to a Portuguese language class.
+student.txt              - This file defines every field in the three files above.
+math_classes.parquet     - This file contains data used in the time series analysis examples.
+
+tutorial_code.ipynb      - This file contains the code used in the tutorial.
+solutions.ipynb          - This file contains the solutions to the exercises.

polars-groupby/course.parquet

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+# Attributes for both student-mat.csv (Math course) and student-por.csv (Portuguese language course) datasets:
+0 subject - subject (binary: "M" - Math or "P" - Portuguese language)
+1 school - student's school (binary: "GP" - Gabriel Pereira or "MS" - Mousinho da Silveira)
+2 sex - student's sex (binary: "F" - female or "M" - male)
+3 age - student's age (numeric: from 15 to 22)
+4 address - student's home address type (binary: "U" - urban or "R" - rural)
+5 famsize - family size (binary: "LE3" - less or equal to 3 or "GT3" - greater than 3)
+6 Pstatus - parent's cohabitation status (binary: "T" - living together or "A" - apart)
+7 Medu - mother's education (numeric: 0 - none,  1 - primary education (4th grade), 2 – 5th to 9th grade, 3 – secondary education or 4 – higher education)
+8 Fedu - father's education (numeric: 0 - none,  1 - primary education (4th grade), 2 – 5th to 9th grade, 3 – secondary education or 4 – higher education)
+9 Mjob - mother's job (nominal: "teacher", "health" care related, civil "services" (e.g. administrative or police), "at_home" or "other")
+10 Fjob - father's job (nominal: "teacher", "health" care related, civil "services" (e.g. administrative or police), "at_home" or "other")
+11 reason - reason to choose this school (nominal: close to "home", school "reputation", "course" preference or "other")
+12 guardian - student's guardian (nominal: "mother", "father" or "other")
+13 traveltime - home to school travel time (numeric: 1 - <15 min., 2 - 15 to 30 min., 3 - 30 min. to 1 hour, or 4 - >1 hour)
+14 studytime - weekly study time (numeric: 1 - <2 hours, 2 - 2 to 5 hours, 3 - 5 to 10 hours, or 4 - >10 hours)
+15 failures - number of past class failures (numeric: n if 1<=n<3, else 4)
+16 schoolsup - extra educational support (binary: yes or no)
+17 famsup - family educational support (binary: yes or no)
+18 paid - extra paid classes within the course subject (Math or Portuguese) (binary: yes or no)
+19 activities - extra-curricular activities (binary: yes or no)
+20 nursery - attended nursery school (binary: yes or no)
+21 higher - wants to take higher education (binary: yes or no)
+22 internet - Internet access at home (binary: yes or no)
+23 romantic - with a romantic relationship (binary: yes or no)
+24 famrel - quality of family relationships (numeric: from 1 - very bad to 5 - excellent)
+25 freetime - free time after school (numeric: from 1 - very low to 5 - very high)
+26 goout - going out with friends (numeric: from 1 - very low to 5 - very high)
+27 Dalc - workday alcohol consumption (numeric: from 1 - very low to 5 - very high)
+28 Walc - weekend alcohol consumption (numeric: from 1 - very low to 5 - very high)
+29 health - current health status (numeric: from 1 - very bad to 5 - very good)
+30 absences - number of school absences (numeric: from 0 to 93)
+
+# these grades are related with the course subject, Math or Portuguese:
+31 G1 - first period grade (numeric: from 0 to 20)
+31 G2 - second period grade (numeric: from 0 to 20)
+32 G3 - final grade (numeric: from 0 to 20, output target)
+
+Additional note: there are several (382) students that belong to both datasets . 
+These students can be identified by searching for identical attributes
+that characterize each student, as shown in the annexed R file.