Pandas common knowledge required for data analysis and mining in PythonObjectivePandas is based on two types of data: series and Dataframe.A series is a one-dimensional data type in which each element has a label. The series is similar to an array of elements tagged in numpy. Where the label can be either a number or a string.A dataframe is a two-dimensional table structure. Pandas's Dataframe can store man
. Data structure:Series: A one-dimensional array, similar to a one-dimensional array in NumPy. The two are similar to the Python basic data Structure list, the difference is that the elements in the list can be different data types, and the array and series only allow the same data types to be stored, so that more efficient use of memory, improve the efficiency of operations. Time-series: A Series that is indexed in time. DataFrame: A two-dimensional
Getting started with Python for data analysis--pandas
Based on the NumPy established
from pandas importSeries,DataFrame,import pandas as pd
One or two kinds of data structure 1. Series
A python-like dictionary with indexes and values
Create a series#不指定索引,默认创建0-NIn [54]: obj = Series([1,2,3,4,5])In [55]: objOut[55]:0 11 22 33 44 5dtype: int64#指定索引In [56]: obj1 = Series([1,2,3,4,5],index=[‘a‘,‘
first, the initial knowledge of pandas
Pandas is a very useful library based on NumPy, which has two unique basic data Structures series (one-dimensional) and dataframe (two-dimensional) that make data operations simpler. Although pandas has two data structures, it is still a library of Python, so some data types in Python are still available here, and you can also use the class to define the data type yourself.
In the field of financial data analysi
Motive
We spend a lot of time migrating data from common interchange formats (such as CSV) to efficient computing formats like arrays, databases, or binary storage. Worse, many people do not migrate data to efficient formats because they do not know how (or cannot) manage specific migration methods for their tools.
The data format you choose is important, and it can strongly affect program performance (the empirical rules indicate a 10 times-fold gap), and those who easily use and understand yo
#-*-Coding:utf-8-*-# The Nineth chapter of Python for data analysis# Data aggregation and grouping operationsImport Pandas as PDImport NumPy as NPImport time# Group operation Process, Split-apply-combine# Split App MergeStart = Time.time ()Np.random.seed (10)# 1, GroupBy technology# 1.1, citationsDF = PD. DataFrame ({' Key1 ': [' A ', ' B ', ' A ', ' B ', ' a '],' Key2 ': [' one ', ' one ', ' one ', ' one ', ' one ',' Data1 ': Np.random.randint (1, 10
#!/usr/bin/env python #-*-coding:utf-8-*-# @Time: 4/14/18 11:17 AM # @Author: Aries # @Site: # @File:
main.py # @Software: Pycharm ' reference: https://www.cnblogs.com/misswangxing/p/7903595.html pandas Getting Started: 1 basic knowledge Pandas:
Meaning: The Python data Analysis Library is a numpy based tool.
Abbreviation: Panel data,data Analysis Features: 1 introduction of the standard data model, provide processing data Method 2 provides a good supporting data structure for time series anal
If you do any data analysis in the Python language, you might use pandas, a wonderful analysis library written by Wes McKinney. By giving Python data frames to analyze functionality, pandas has effectively placed Python in the same position as some of the more sophisticated analysis tools such as R or SAS.Add QQ group 813622576 or Vx:tanzhouyiwan free to receive Python learning materialsUnfortunately, in the early days, pandas was notorious for "slow". Indeed, the pandas code cannot achieve the
Pandas: data Analysis Library built on NumPyPANDAS data structure: Series, DataFrameSeries: class one-dimensional array objects with data labels (also considered as dictionaries)Values, indexMissing data detection: Pd.isnull (), Pd.notnull (), instance method for series objectsThe series object itself and its index have a Name property, which is closely related to pandas other key functionsDataFrame: Tabular data structures, columns and rows are indexedGet d
Spark SQL and DataFrame
1. Why use Spark SQL
Originally, we used hive to convert the hive SQL to map Reduce and then commit to the cluster to execute, greatly simplifying the complexity of the program that wrote MapReduce, because this model of mapreduce execution efficiency is slow, so spark Sql came into being, It is to convert the Sparksql into an rdd and then commit to the cluster execution, which is very efficient to execute.
Spark SQL a bit:
Spark SQL 1.3refer to the official documentation: Spark SQL and DataFrame GuideOverview Introduction Reference: Approachable, inclusive--spark SQL 1.3.0 overview DataFrame提供了A channel that connects all the main data sources and automatically translates into a parallel processing format through which spark can delight all players on the big data ecosystem, whether it's a data scientist using R, a business a
,how=‘left‘) #df_right=pd.merge(df,df1,how=‘right‘)df_outer=pd.merge(df,df1,how=‘outer‘) #并集2. Set the index columndf_inner.set_index(‘id‘)3. Sort by the value of a specific column:df_inner.sort_values(by=[‘age‘])4. Sort by index column:df_inner.sort_index()5. If the value >3000,group column of the Prince column shows high, the low is displayed:df_inner[‘group‘] = np.where(df_inner[‘price‘] > 3000,‘high‘,‘low‘)6, the composite multiple conditions of the data grouping tagdf_inner.loc[(df_
write in front: by yesterday's record we know, pandas.read_csv (" file name ") method to read the file, the variable type returned is dataframe structure . Also pandas one of the most core types in . That in pandas there is no other type Ah, of course there are, we put dataframe type is understood to be data consisting of rows and columns, then dataframe
inspired by the Scikit-learn project and summed up the drawbacks of MLlib in dealing with complex machine learning issues, designed to provide users with a higher-level API library based on DataFrame to make it easier to build complex Machine learning workflow applications.
A Pipeline is structurally composed of one or more pipelinestage, each pipelinestage a task, such as data set processing conversions, model training, parameter setting, or data pr
) = 0,
2X ^ TXw-2X ^ Ty = 0
X ^ TXw = X ^ Ty
If X ^ TX is full, it is reversible. Therefore, the left side of both sides is multiplied by (X ^ TX) ^-1 at the same time.
Therefore:
W = (X ^ TX) ^-1) X ^ Ty, that is, the preceding result.
The following is our Python code:
#-*-Coding: UTF-8-*-"Created on Tue Oct 10 23:10:00 2017 Version: python3.5.1 @ author: Stone" "import pandas as pdfrom numpy. linalg import invfrom numpy import dot # regular equation method # fitting linear model: Sepal. length
Pandas Select Data Iloc and LOC are not used the same way, Iloc is based on the index, LOC is based on the value of the row>>>importpandasaspd>>>importos>>>os.chdir ("d:\\") >>>d=pd.read_csv ("Gwas_water.qassoc",delimiter= "\s+") >> >d.loc[1:3]CHRSNPBPNMISS BETASER2 tp11. 447440.18000.17830.02369 1.0090.318521.449 440.27850.24730.029311.1260.26653 1.452440.1800 0.17830.023691.0090.3185>>>d.loc[0:3]chrsnp BP
function value def cost (Theta, x, y): Theta = NP. matrix (theta) x = NP. matrix (x) y = NP. matrix (y) Part1 = NP. multiply (-y, NP. log (sigmoid (x * Theta. t) Part2 = NP. multiply (1-y), NP. log (1-sigmoid (x * Theta. t) return NP. sum (part1-part2)/Len (x) # Add one column before the original matrix 1st to all 1data. insert (0, 'ones', 1) Cols = data. shape [1] x = data. iloc [:, 0: Cols-1] Y = data. iloc
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