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Article contents:[[tags:egg]] [[toc:]] == dataframe Tabular data structure implementation for data analysis. == Documentation The {{dataframe}} library provides an interface for representing numerical data in tables with rows and columns. It is inspired by the various dataframe implementations found in R, Python and Racket. The {{dataframe}} library also provides functions for loading and saving data from data frames as well as routines for descriptive statistics and linear regression. === Columns Each dataframe consists of a collection of columns, which in turn is an object consisting of a unique key, data collection, and an associative list of properties. The following operations are defined on columns. <procedure>(column? obj)</procedure> Returns true if the given object is a column. <procedure>(get-column-properties column)</procedure> Returns an associative list with column properties. <procedure>(get-column-key column)</procedure> Returns the key of the column. <procedure>(get-column-collection column)</procedure> Returns the data collection of the column. <procedure>(column-deserialize column port)</procedure> Loads the data collection of a column from the given port. <procedure>(column-serialize column port)</procedure> Stores the data collection of a column to the given port in an s-expression format. === Creating data frames <procedure>(make-data-frame [column-key-compare: compare-symbol])</procedure> Creates a new dataframe, with optional argument a procedure that specifies how to compare column keys. Default is comparison on symbols. Returns the new dataframe. <procedure>(df-insert-column df key collection properties)</procedure> Inserts a new column with the given key, data collection, and properties. Returns a new dataframe with the inserted column. <procedure>(df-insert-derived df parent-key key proc properties)</procedure> Inserts a derived column, that is a column whose data elements are obtained by mapping a procedure onto the elements of an existing (parent) column. Returns a new dataframe with the inserted column. <procedure>(df-insert-columns df lseq)</procedure> Inserts the columns contained in the given lseq of column objects. <procedure>(df-from-rows column-keys source [column-key-compare: compare-symbol])</procedure> Creates a data frame with the given column keys and populates it with data from the row generator SOURCE. === Accessing data frames <procedure>(show df)</procedure> Displays a subset of the rows and columns contained in the dataframe. <procedure>(row-count df)</procedure> Returns the number of rows in the dataframe. <procedure>(df-column df key)</procedure> Returns the column indicated by the given key. <procedure>(df-columns df)</procedure> Returns a lazy sequence containing the columns of the dataframe. <procedure>(df-filter-columns df proc)</procedure> Returns a filtered lseq of the columns of the dataframe according to the given filter predicate procedure. <procedure>(df-select-columns df keys)</procedure> Returns an lseq of the columns of the dataframe that have the keys enumerated in the given list of keys. <procedure>(df-keys df)</procedure> Returns the keys of all columns in the dataframe. <procedure>(df-items df)</procedure> Returns an lseq of the key-column pairs contained in the dataframe. <procedure>(apply-collections proc df key ...)</procedure> Applies the given procedure to the data collections of the named columns of the dataframe and returns the result as a list. <procedure>(apply-columns proc df key ...)</procedure> Applies the given procedure to the named columns of the dataframe and returns the result as a list. <procedure>(map-collections proc df key ...)</procedure> Applies the given procedure to the data collections of the named columns of the dataframe and returns the result as a dataframe. <procedure>(map-columns proc df key ...)</procedure> Applies the given procedure to the named columns of the dataframe and returns the result as a dataframe. <procedure>(reduce-collections proc df seed key ...)</procedure> Fold over the data collections of the named columns. === Iterators <procedure>(df-for-each-column df proc)</procedure> Applies proc to each column. <procedure>(df-for-each-collection df proc)</procedure> Applies proc to the data collection of each column. <procedure>(df-gen-rows df)</procedure> Returns a generator procedure that returns the dataframe rows in succession. <procedure>(df-gen-columns df)</procedure> Returns a generator procedure the returns the dataframe columns in succession. === Descriptive statistics <procedure>(describe df port)</procedure> Displays a table with the min/max/mean/sdev of each column in the dataframe. <procedure>(cmin df)</procedure> Computes the minimum value of each column. <procedure>(cmax df)</procedure> Computes the maximum value of each column. <procedure>(mean df)</procedure> Computes the mean value of each column. <procedure>(median df)</procedure> Computes the median value of each column. <procedure>(mode df)</procedure> Computes the mode value of each column. <procedure>(range df)</procedure> Computes the difference between maximum and minimum value of each column. <procedure>(percentile df)</procedure> Computes the percentile values of each column. <procedure>(variance df)</procedure> Computes the variance of each column. <procedure>(standard-deviation df)</procedure> Computes the standard deviation of each column. <procedure>(coefficient-of-variation df)</procedure> Computes the coefficient of variation of each column. === Regression and correlation <procedure>(linear-regression df x y)</procedure> Linear regression between columns x and y. <procedure>(correlation-coefficient df x y)</procedure> Correlation coefficient between columns x and y. === I/O <procedure>(df-serialize df port)</procedure> Stores the dataframe in an s-expression format to the given port. <procedure>(df-deserialize df port)</procedure> Loads the data collections of the dataframe columns from the given port. == Examples <enscript highlight="scheme"> (import scheme yasos dataframe dataframe-statistics) (define df (make-data-frame)) (define df1 (df-insert-column df 'base (list-tabulate 100 (lambda (x) (- x 10))) '())) ;; exponential series (define df2 (df-insert-derived df1 'base 'exp (lambda (x) (* 2.0 (exp (* 0.1 x)))) '() )) (show df2 #f) (describe df2 #f) (linear-regression df2 'base 'exp) </enscript> == About this egg === Author [[/users/ivan-raikov|Ivan Raikov]] === Repository [[https://github.com/iraikov/chicken-dataframe|https://github.com/iraikov/chicken-dataframe]] === Version history ; 0.1 : Initial release === License Copyright 2019 Ivan Raikov. This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. A full copy of the GPL license can be found at <http://www.gnu.org/licenses/>. Description of your changes:

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