I-Pandas iwumtapo wezincwadi wePython osetshenziswa kabanzi emkhakheni wokukhohlisa nokuhlaziya idatha. Ihlinzeka ngezakhiwo zedatha nemisebenzi edingekayo ukuze kusetshenzwe nedatha ehlelekile kalula. Esinye sezici eziningi ezinikezayo yikhono lokuhlanganisa amathebula ngokhiye abangahlukile, okungaba yimfuneko evamile ezinhlelweni zokusebenza. Kulesi sihloko, sizongena esixazululweni sale nkinga, sihlole incazelo yesinyathelo nesinyathelo sekhodi esetshenziselwa ukujoyina izinto ze-pandas DataFrame ezinokhiye abangahlukile, futhi sixoxe ngemitapo yolwazi nemisebenzi ehilelekile kule nqubo.
Isingeniso
Ukujoyina amathebula kuwumsebenzi oyisisekelo owenziwa emisebenzini yokukhohlisa nokuhlaziya idatha. Kwezinye izimo, kungase kudingeke ukuthi sijoyine amathebula ngokhiye ongahlukile, ongaletha izinselele. Nokho, ukusebenza nomtapo wezincwadi wePython onamandla, ama-panda, kusivumela ukuba sixazulule kahle le nkinga sisebenzisa ukusebenza kwawo okuguquguqukayo.
Ukujoyina ama-Pandas DataFrames Nokhiye Abangebona Abahlukile
Ukujoyina ama-DataFrames kuma-panda, singasebenzisa umsebenzi othi `hlanganisa()`, osekela ukujoyina kokhiye abangahlukile. Kodwa-ke, kubalulekile ukuqonda ukuthi umphumela wokujoyina okhiye abangajwayelekile ungase uhluke kunalokho okulindelekile, njengoba kungaholela kumkhiqizo we-cartesian, okungase kubangele ukwanda okukhulu kwenani lemigqa ku-DataFrame ewumphumela.
Nansi inkomba yesinyathelo ngesinyathelo ekusebenziseni `hlanganisa()` umsebenzi ukuze ujoyine ama-DataFrames ngokhiye abangahlukile:
import pandas as pd
# Create sample DataFrames
df1 = pd.DataFrame({"key": ["A", "B", "A", "C"], "value": [1, 2, 3, 4]})
df2 = pd.DataFrame({"key": ["A", "B", "A", "D"], "value2": [5, 6, 7, 8]})
# Perform the merge operation
result = df1.merge(df2, on="key", how="inner")
Esibonelweni esingenhla, siqala ngokungenisa umtapo wezincwadi we-panda bese sakha amasampula eDathaFrames (df1 kanye ne-df2). Bese, sisebenzisa umsebenzi othi `hlanganisa()` ukuze ujoyine ama-DataFrames kukholamu “yokhiye”, equkethe amanani angahlukile (A no-B bayaphindwa). Ipharamitha ethi `kanjani` isethwe kokuthi "ngaphakathi", njengoba sifuna ukugcina kuphela imigqa enokhiye abafanayo kuwo womabili amaFrames wedatha.
Ukuqonda Umsebenzi Wokuhlanganisa wePandas
Umsebenzi `wokuhlanganisa()` kuma-panda uyithuluzi elinamandla kakhulu futhi elivumelana nezimo ukwenza imisebenzi yokuhlanganisa ithebula. Ngaphezu kokujoyina ama-DataFrames anokhiye abangahlukile, isekela amazinga ahlukene okwenza ngokwezifiso, okukuvumela ukuthi ube nokulawula okugcwele phezu kwe-DataFrame ewumphumela.
Umsebenzi `hlanganisa()` unemingcele eminingana ebalulekile njenge:
- kwesokunxele futhi kwesokudla: Lawa ama-DataFrames azohlanganiswa.
- on: Ikholomu okufanele isetshenziselwe ukujoyina ama-DataFrames. Leli kungaba igama lekholomu eyodwa noma uhlu lwamagama ekholomu lapho ujoyina kumakholomu amaningi.
- Kanjani: Ichaza uhlobo lokuhlanganisa okufanele kwenziwe. Izinketho zifaka phakathi 'kwesokunxele', 'kwesokudla', 'ngaphandle', kanye 'nangaphakathi'. Okuzenzakalelayo 'ngaphakathi'.
- izijobelelo: Lesi isijobelelo seyunithi yezinhlamvu okufanele sisetshenziswe kumakholomu agqagqene. Isijobelelo esimisiwe sithi _x ku-DataFrame kwesokunxele kanye _y ye-DataFrame elungile.
Lawa mapharamitha angashintshwa ngokwezidingo zakho ukuze wenze izinhlobo ezahlukahlukene zokujoyina futhi wenze ngokwezifiso okukhiphayo.
Imisebenzi efanayo kumaPanda
Ngaphandle komsebenzi othi `hlanganisa()`, ama-panda aphinde anikeze eminye imisebenzi yokuhlanganisa ama-DataFrame ngezindlela ezahlukene, njenge:
- i-concat(): Lo msebenzi usetshenziselwa ukuhlanganisa ama-DataFrames ku-eksisi ethile. Ungakwazi ukulawula ukuhlanganisa ngokucacisa amapharamitha ahlukahlukene njenge-eksisi, ukujoyina, nokhiye.
- ujoyine (): Lena indlela elula etholakala ezintweni ze-DataFrame ukwenza imisebenzi yokujoyina. Empeleni igoqa elizungeze umsebenzi we-merge(), kanti i-DataFrame engakwesokunxele ithathwa njengomshayeli we-DataFrame.
Sengiphetha, ngokusebenzisa umsebenzi we-pandas `hlanganisa()`, ungakwazi ukujoyina kalula ama-DataFrame ngokhiye abangahlukile. Isethi enothile yamapharamitha atholakala kumsebenzi othi `hlanganisa()` inikeza ukulawula okugcwele phezu kwenqubo yokuhlanganisa, ibhekelela izidingo ezihlukahlukene zokukhohlisa idatha. Umtapo wezincwadi we-panda uyaqhubeka nokuba yithuluzi elibalulekile labahlaziyi bedatha futhi unikeza eminye imisebenzi ehlukahlukene ukuhlanganisa kanye nokukhohlisa ama-DataFrames ngempumelelo.
