import pandas as pd
reviews = pd.read_csv("./winemag-data-130k-v2.csv", index_col=0)
pd.set_option('max_rows', 5)

Renaming

若要更新column的name

可以用rename function

rename(columns=({'points':'score'}))，可將points替換成score

reviews.rename(columns=({'points':'score'}))

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若要對index做更新，則將rename中的column更改為index

rename(index={0:'firstEntry', 1:'secondEntry'})

reviews.rename(index={0:'firstEntry', 1:'secondEntry'})

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row和column都會有自己的attribute name

可以使用rename_axis替換掉row和column的name

reviews.rename_axis("wines", axis='rows').rename_axis("fields", axis='columns')

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Combining

在pandas中有3個主要合併DataFrame和Series的funciton

concat、merge、join，merge做的事和join很像，因此先忽略這個function

concat

concat可以將dataframe向下合併，若要忽略index，可使用ignore_index = True parameter

canadian_youtube = pd.read_csv('./CAvideos.csv')
british_youtube = pd.read_csv('./GBvideos.csv')

pd.concat([canadian_youtube, british_youtube])

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若要左右合併dataframe，可使用join()函式

會根據相同的index對資料做合併

left = canadian_youtube.set_index(['title', 'trending_date'])
right = british_youtube.set_index(['title', 'trending_date'])

left.join(right, lsuffix='_CAN', rsuffix='_UK')

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