merge data frames pandas

join and specify Keys (row index) \ r \ n ', concat ([df1,df2],keys=[' A ', ' B ']) # Here are the duplicate data print ' go back \ r \ n ', concat ([df1,df2],ignore_index=true). Drop_duplicates ()The output is:Internal connection by Axis City rank City rank0 Chicago 1 Chicago San Francisco 2 Boston New York City 3 Los Angeles 5 outer Joins and assign keys (row index) City Ranka 0 Chicago 1 1 San F

1 concat The Concat function is a method underneath the pandas that allows for a simple fusion of data based on different axes. Pd.concat (Objs, axis=0, join= ' outer ', Join_axes=none, Ignore_index=false, Keys=none, Levels=none, Names=None, Verify_integrity=false)1 2 1 2 1 2 Parameter descriptionObjs:series,dataframe or a sequence of panel compositions lsitAxis: Axis that needs to

have the following advantages: Faster (once set) Self-explanation (by checking the code, you will know what it has done) Easy to generate reports or emails More flexible, because you can define custom Aggregate functions Read in the data First, let's build the required environment. If you want to continue with me, you can download this Excel file. Import pandas as pd Import numpy as np Vers

Http://www.cnblogs.com/batteryhp/p/5006274.htmlPandas is the preferred library for subsequent content in this book. The pandas can meet the following requirements: Data structure with automatic or explicit data alignment by axis. This prevents many common errors caused by data misalignment and

(' ABCD ')) print DF #定义一个函数 def _sum (x): print (Type (x)) C1/>return x.sum () #apply函数可以接受一个函数作为参数 print df.apply (_sum) s = PD. Series (np.random.randint (10,20,size =)) print s #统计序列中每个元素出现的次数 print s.value_counts () #返回出现次数最多的元素 print S.mode () Some of the 12.DataFrame operations (10) Import NumPy as NP import pandas as PD DF = PD. DataFrame (Np.random.randn (10,4), columns = List (' ABCD ')) print df #合并函数 DFL = Pd.concat ([Df.iloc[:3],df.

At the time of data processing, especially in the big data contest, often encounter a problem is that multiple forms of merging problems, such as a form has user_id and age two fields, another form has user_id and sex two fields, to merge these two tables into only user_id, Age, sex three fields of the table what to do, the ordinary stitching is not possible, bec

attach data rows. We'll use the Dataframe in the previous section to practice concatenation and additional operations on data rowsfunction concat () is a concatenation dataframe, such as a dataframe consisting of 3 rows of data can be concatenated with other data rows in order to reconstruct the original dataframe:Pri

Using Python for data analysis (12) pandas basics: data merging and pythonpandas Pandas provides three main methods to merge data: Pandas. merg