型別專屬 Expectations

Great Expectations 資料品質入門

Davina Moossazadeh

Data Scientist

數值 Expectations：彙總層級

gx.expectations.ExpectColumnMeanToBeBetween(
    column="mark_price_usd", min_value=20, max_value=25
)

gx.expectations.ExpectColumnMedianToBeBetween(
    column="mark_price_usd", min_value=20, max_value=25
)

gx.expectations.ExpectColumnStdevToBeBetween(
    column="mark_price_usd", min_value=15, max_value=20
)

gx.expectations.ExpectColumnSumToBeBetween(
    column="mark_price_usd", min_value=20000, max_value=21000
)

數值 Expectations：列層級

設定列層級的數值範圍 Expectations：

gx.expectations.ExpectColumnValuesToBeBetween(
    column="star_rating", min_value=0, max_value=5
)

或順序：

gx.expectations.ExpectColumnValuesToBeIncreasing(
    column="price_usd"
)

gx.expectations.ExpectColumnValuesToBeDecreasing(
    column="price_usd"
)

字串 Expectations

設定字串欄位的 Expectations（皆為列層級）：

gx.expectations.ExpectColumnValueLengthsToEqual(
    column="sku_id", value=18
)

gx.expectations.ExpectColumnValuesToMatchRegex(
    column="link", regex="^https://us.shein.com/[\w-]+"
)

regex_list = [
    "//img.ltwebstatic.com/images3_(spmp)|(pi)/202[0-4]/[0-1][0-9]/.*",
    "//sheinsz.ltwebstatic.com/she_dist/images/bg-g.*"
]

gx.expectations.ExpectColumnValuesToMatchRegexList(
    column="hero_image", regex_list=regex_list
)

字串可解析性 Expectations

為字串欄位設定可解析性的 Expectations，確保資料可被解析。

ExpectColumnValuesToBeDateutilParseable() 用於日期：

gx.expectations.ExpectColumnValuesToBeDateutilParseable(
    column="colour"
)

ExpectColumnValuesToBeJsonParseable() 用於 JSON：

gx.expectations.ExpectColumnValuesToBeJsonParseable(
    column="colour"
)

小抄速覽

數值 Expectations：

ExpectColumn<METRIC>ToBeBetween(
    column, min_value, max_value
)
# <METRIC> in {"Mean", "Median", "Stdev", "Sum"}

ExpectColumnValuesToBeBetween(
    column, min_value, max_value
)

ExpectColumnValuesToBeIncreasing(column)

ExpectColumnValuesToBeDecreasing(column)

字串 Expectations：

ExpectColumnValueLengthsToEqual(column, value)

ExpectColumnValuesToMatchRegex(column, regex)

ExpectColumnValuesToMatchRegexList(
    column, regex_list
)

ExpectColumnValuesToBeDateutilParseable(column)

ExpectColumnValuesToBeJsonParseable(column)

一起來練習吧！

Great Expectations 資料品質入門