17. Python - Pandas - Renaming/Combining

 Changing names:

// Columns:

data_frame.rename(columns = {'OLDNAME' : 'NEWNAME'})

// can add multiple renames by adding a comma


// Index:

data_frame.rename(index = {0: 'first index' , 1: '2nd index'})

// set_index() is more convenient.


// Axis Index

data_frame.rename_axis("AXISNAME_A", axis = 'rows').rename_axis("AXISNAME_B", axis = "columns")

// renames whole 2 axis, the row and the column


Combining:

// concat():

pd.concat([data_frame_1, data_frame_2])

// combines two data frames who have the same columns(fields) into one data frame

// basically places both data under the same columns


// join():

left = data_frame_1.set_index(['FIRST INDEX' , 'SECOND INDEX'])

right = data_frame_2.sex_index(['FIRST INDEX' , 'SECOND INDEX'])

left.join(right, lsuffix = '_FIRSTDATA', rsuffix='_2NDDATA')

// creates a new data frame and combine 2 data frames data if they have the same indexes and then merges them into a long row, the suffix lets us differentiate between 2 data in the row by making every column below to each data frame.

// if the data have different column values, we wont need to add suffix because we cant mix them up since they are not the same.


// merge():


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