JavaScript - 从二维数组中过滤数组

Question

I'm attempting to add a condition to my 2D array that I am getting back from an API call. The data being returned is a top 3 rankings for state. So for example, there are 3 values that read "California" with the second index being the rank. I am attempting to apply a condition to filter out any state that does not return appear 3 times, for example: If (state name) does not have 1, 2, 3 dont return. My issue is that I do not know how to apply this logic successfully.

I've attempted looping through an array and putting a condition if the state name does not happen 3 times, remove from the array.

My expected result would be this:

const data = [ [ "California", 1 , 23432], ["Califonria", 2, 22132], ["California", 3, 49343], ["New York", 1, 3231], ["New York", 2 , 3023], ["New York", 3, 2932]

here is a snippet that i've tried:

 const data = [ [ "California", 1, 23432], ["Califonria", 2, 22132], ["California", 3, 49343], ["New York", 1, 3231], ["New York", 2, 3023], ["New York", 3, 2932], ["Georgia", 1, 3423]] for (let i = 0; data.length > i; i++) { if (data[0].length < 3) { data.splice(i,1) } } console.log(data)

Answer 1

You can build a count of how many times each state name occurs in your original array and then filter the array based on the count being 3 for that state name:

 const data = [ ["California", 1, 23432], ["California", 2, 22132], ["California", 3, 49343], ["New York", 1, 3231], ["New York", 2, 3023], ["New York", 3, 2932], ["Georgia", 1, 3423] ]; const counts = data.reduce((c, v) => { c[v[0]] = (c[v[0]] || 0) + 1; return c; }, {}); const result = data.filter(v => counts[v[0]] == 3); console.log(result);