The loc and iloc methods enable you to retrieve subsets based on row and column labels or by integer index of the rows and columns.Īnd Pandas has a bracket notation that enables you to use logical conditions to retrieve specific rows of data.īut both of those tools can be a little cumbersome syntactically. query() and what does it do? Query is a tool for querying dataframes and retrieving subsetsĪt a very high level, the Pandas query method is a tool for generating subsets from a Pandas DataFrame.įor better or worse, there are actually several ways to generate subsets with Pandas. It is a comprehensive toolkit for working with data and performing data manipulation on DataFrames.Īmong the many tools for performing data manipulation on DataFrames is the Pandas query method. Pandas has tools for performing all of these tasks. Here, I’m talking about things like subsetting, grouping, and aggregating. Moreover, once your data are in the DataFrame structure and the data are “clean,” you’ll still need to use some “data manipulation” techniques to analyze your data. If your data are a little “dirty,” you might need to use some tools to clean the data up: modifying missing values, changing string names, renaming variables, adding variables, etc. Once you have your data inside of a dataframe, you’ll very commonly need to perform data manipulation. Pandas methods perform operations on DataFrames There are several ways to create a DataFrame, including importing data from an external file (like a CSV file) and creating DataFrames manually from raw data using the pandas.DataFrame() function.įor more information about DataFrames, check out our tutorial on Pandas DataFrames. A Pandas DataFrame is very similar to an Excel spreadsheet, in that a DataFrame has rows, columns, and cells. If you’ve worked with Microsoft Excel, you should be familiar with this structure. To get a little more specific, Pandas is a toolkit for creating and working with a data structure called a DataFrame.Ī DataFrame is a structure that we use to store data.ĭataFrames have a row-and-column structure, like this: It is a critical toolkit for doing data science in Python. Specifically, Pandas is a toolkit for performing data manipulation in Python. Pandas is a package for the Python programming language. Very quickly, let’s review what Pandas is. Everything will make more sense that way. If you need something specific (like help with syntax, examples, etc), you can click on one of the following links and it will take you to the appropriate section.īut if you’re new to Pandas, or new to data manipulation in Python, I recommend that you read the whole tutorial. The tutorial will explain the syntax and also show you step-by-step examples of how to use the Pandas query method. Gist so people can make forks and update if they want.This tutorial will show you how to use the Pandas query method to subset your data. There are other things you could do to this file to make it even more portableīut this should give you the idea. name ) save_report ( sales_report, args. parse_args () # We need to pass the full file name instead of the file object sales_report = create_pivot ( args. FileType ( 'w' ), help = "output file in Excel" ) args = parser. add_argument ( 'outfile', type = argparse. FileType ( 'r' ), help = "report source file in Excel" ) parser. add_argument ( 'infile', type = argparse. ArgumentParser ( description = 'Script to generate sales report' ) parser. save () if _name_ = "_main_" : parser = argparse. ExcelWriter ( outfile ) for manager in report. pivot_table ( df, index = index_list, values = value_list, aggfunc =, fill_value = 0 ) return table def save_report ( report, outfile ): """ Take a report and save it to a single Excel file """ writer = pd. """ import argparse import pandas as pd import numpy as np def create_pivot ( infile, index_list =, value_list = ): """ Read in the Excel file, create a pivot table and return it as a DataFrame """ df = pd. The output is saved in multiple tabs in a new Excel file. """ Sample report generation script from This program takes an input Excel file, reads it and turns it into a pivot table.
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