What Does It Mean To "Clip" A Polygon?

Question

I have the following dataset in R - this dataset contains a list of geocoded addresses (Canada) with their Postal Codes, Longitudes and Latitudes: https://www.dropbox.com/scl/fi/9kjoqsppb85ip0tdc5wmr/stackoverflow_example.csv?rlkey=cwjk222jnoz8c9cgbt01p6bep&dl=0

I loaded this data into R:

library(httr)
library(data.table)

url <- "https://www.dropbox.com/scl/fi/9kjoqsppb85ip0tdc5wmr/stackoverflow_example.csv?rlkey=cwjk222jnoz8c9cgbt01p6bep&dl=1"

response <- GET(url)

df <- fread(content(response, "text"), sep = ",", quote = "", fill = TRUE)


> head(df)
         "" "latitude" "longitude" "source_id"                   "id" "group_id" "street_no"            "street"       "str_name" "str_type" "str_dir" "unit"     "city" "postal_code"
1: "999976"   44.25845   -76.46308          "" "6baaa1692aaaa7b496aa"    2494328       "104" "POINT ST. MARK DR" "POINT ST. MARK"       "DR"        ""     "" "KINGSTON"     "K7K 6X8"
2: "999977"   44.26391   -76.45090          "" "1f01e7839e59727d95a3"    2508891       "229"      "GREENLEES DR"      "GREENLEES"       "DR"        ""     "" "KINGSTON"     "K7K 6R1"
3: "999978"   44.26262   -76.45164          "" "289d509f161955a7b5ad"    2519600       "443"        "MAUREEN ST"        "MAUREEN"       "ST"        ""     "" "KINGSTON"     "K7K 7M2"
4: "999979"   44.26545   -76.45230          "" "e6516f9c0e173b684627"    2506548       "198"      "GREENLEES DR"      "GREENLEES"       "DR"        ""     "" "KINGSTON"     "K7K 6P7"
5: "999983"   44.23525   -76.49264          "" "2576c9ff82b86638737c"    2508273        "22"         "ELLICE ST"         "ELLICE"       "ST"        ""     "" "KINGSTON"     "K7K 1M5"
6: "999993"   44.26520   -76.45182          "" "03aaecc65f29e1e04fe1"    2507798       "212"      "GREENLEES DR"      "GREENLEES"       "DR"        ""     "" "KINGSTON"     "K7K 6P7"
               "full_addr" "city_pcs" "str_name_pcs" "str_type_pcs" "str_dir_pcs" "csduid"  "csdname" "pruid"         "provider"
1: "104 POINT ST. MARK DR" "KINGSTON"   "PT ST MARK"           "DR"            ""  3510010 "Kingston"      35 "City of Kingston"
2:      "229 GREENLEES DR" "KINGSTON"    "GREENLEES"           "DR"            ""  3510010 "Kingston"      35 "City of Kingston"
3:        "443 MAUREEN ST" "KINGSTON"      "MAUREEN"           "ST"            ""  3510010 "Kingston"      35 "City of Kingston"
4:      "198 GREENLEES DR" "KINGSTON"    "GREENLEES"           "DR"            ""  3510010 "Kingston"      35 "City of Kingston"
5:          "22 ELLICE ST" "KINGSTON"       "ELLICE"           "ST"            ""  3510010 "Kingston"      35 "City of Kingston"
6:      "212 GREENLEES DR" "KINGSTON"    "GREENLEES"           "DR"            ""  3510010 "Kingston"      35 "City of Kingston"

My Question: Using this data, I am trying to "approximate" the geographical boundary of each Postal Code and visualize the result.

In the past, it was suggested to me that a technique called "Polygon Clipping" might be useful for accomplishing this task.

I am trying to learn how "Polygon Clipping" might be useful in accomplishing this task - but I am not sure how to get started with this. In the end, I would like to have something like a shapefile that contains the "perimeter" (in longitude and latitude coordinates) of each Postal Code.

How can I do this?

Note:

• Original Source of Full Data : https://www.statcan.gc.ca/en/lode/databases/oda
• Related Question: Building a shapefile for Canadian postal codes

Answer 1

"Polygon clipping" in GIS means to take one polygon, A, and a clipping polygon, B, and compute the bits of A that are inside B. For example you might have a polygon of forest, and a polygon of a state boundary, and clipping the forest to the state boundary gives you the forest inside the state.

I don't see how this helps you define polygon regions for your postcode centres, but it answers the question in the title.