GEE study notes (1)

The difference between Google Earth Engine and Google Earth:
Google Earth: observation tool
Google Earth Engine: analysis of earth science data

GEE registration: https://signup.earthengine.google.com
GEE case: https://earthengine.google.com/case_studies/

GUI of GEE

https://explorer.earthengine.google.com/#workspace

3. Know the GEE application programming interface (API)

The top search box can search for geographic locations and data sets

4. GEE data type

String Number Array List Dictionary
1.String

print('Hello World')
var string_1 = ee.String('Hello') 
var string_2 = ee.String('World')
var cat_string = string_1.cat(string_2)
print(cat_string)

var string_1 = ee.String('ABC AEF AMN') 
var string_2 = string_1.replace('A', '-')
print(string_1, string_2)

ABC AEF AMN
-BC AEF AMN

var string_1 = ee.String('A_B_C_D_E') 
var string_2 = string_1.split('_')
print(string_1, string_2)

A_B_C_D_E
[“A”,“B”,“C”,“D”,“E”]

i: Ignore case
g: global match

var string_1 = ee.String('A B C D C') 
var string_2 = string_1.match('C','i')
print(string_1, string_2)
var string_2 = string_1.match('C','g')
print(string_1, string_2)

A B C D C
[“C”]
A B C D C
[“C”,“C”]

var string_1 = ee.String('1234 5678 9876') 
var string_2 = string_1.slice(5,10)
print(string_1, string_2)
var string_2 = string_1.slice(5)
print(string_1, string_2)

1234 5678 9876
5678
1234 5678 9876
5678 9876

var string_1 = ee.String('1234 5678 9876') 
var number = string_1.length()
print(string_1, number)

1234 5678 9876
14

2.Number

var number = ee.Number(-3.1415926)
var number_1 = number.int8()
var number_2 = number.toInt8()
print(number, number_1, number_2)

var panDuan = number_1.eq(number)
print(panDuan)
var panDuan = ee.Algorithms.IsEqual(number, number_1)
print(panDuan)
var panDuan = ee.Algorithms.IsEqual(number_2, number_1)
print(panDuan)
/*
eq:=   neq:不等号  gt:>   gte:>=  lt:<  lte:<=  
and()  or()  not()
*/
var abs = number.floor().abs()
print(abs)
/*
round:四舍五入  ceil:向上取整   sqrt exp log log10 
*/

-3.1415926
-3
-3
0
false
true
4
3.Dictionary

var Dictionary_Profile = ee.Dictionary({
    
    
  Name:'Houyw',
  Gerder:'Male',
  Age:'>20',
  Location:'BeiJing'
})
print(Dictionary_Profile) //输出的顺序是key的字典字典顺序  

var Dict_1 = ee.Dictionary({
    
    Weight:'50kg', Hight:'160cm'})
var Dict_2 = ee.Dictionary({
    
    Weight:'70g', Age:'26'})
print(Dict_1.combine(Dict_2, true)) // true:发生冲突的时候以第二个为准 
print(Dict_1.combine(Dict_2, false))

Object (4 properties)
Age: >20
Gerder: Male
Location: BeiJing
Name: Houyw
Object (3 properties)
Age: 26
Hight: 160cm
Weight: 70g
Object (3 properties)
Age: 26
Hight: 160cm
Weight: 50kg

var Dictionary_Profile = ee.Dictionary({
    
    
  Name:'Houyw',
  Gerder:'Male',
  Age:'>20',
  Location:'BeiJing'
})
var Dict_Change = Dictionary_Profile.set('Age', '<30')
print(Dict_Change) //输出的顺序是key的字典字典顺序  
print(Dict_Change.keys())
print(Dict_Change.get('Name'))
print(Dict_Change.values(['Name','Age','Location']))
print(Dict_Change.contains('Hight')) // 判断 Dict_Change 是否包含 Hight
print(Dict_Change.size())

Object (4 properties)
Age: <30
Gerder: Male
Location: BeiJing
Name: Houyw
["Age", "Gerder", "Location", "Name"]
0: Age
1: Gerder
2: Location
3: Name
Houyw
[" Houyw ”," <30 "," BeiJing "]
0: Houyw
1: <30
2: BeiJing
false
4

4.List

var list = ee.List([1,2,3,2,'A','B',['c','d','e']])
print(list)
print(ee.List.repeat('Hello', 5))

// 最后一个是产生的个数  
print(ee.List.sequence(0,9,1,null))
print(ee.List.sequence(0,9,null,4))
print(list.set(0,2))
print(list.set(-1,33333))

print(list.replace(2,20))
print(list.replaceAll(2,20))

[1,2,3,2,“A”,“B”,[“c”,“d”,“e”]]
[“Hello”,“Hello”,“Hello”,“Hello”,“Hello”]
[0,1,2,3,4,5,6,7,8,9]
[0,3,6,9]
[2,2,3,2,“A”,“B”,[“c”,“d”,“e”]]
[1,2,3,2,“A”,“B”,33333]
[1,20,3,2,“A”,“B”,[“c”,“d”,“e”]]
[1,20,3,20,“A”,“B”,[“c”,“d”,“e”]]

var list = ee.List([1,1,2,3])
print(list.add('add')) // 末尾add 
print(list.insert(2,'insert'))

var list_zip = ee.List([4,5,6,7])
print(list.zip(list_zip))
print(list.reverse())
print(list.rotate(2))  //2 is value , 以2开头 在排序
print(list_zip.sort())

var list_flatten = ee.List([
  [[22],[33]],
  [[44],[55]]
])
print(list_flatten.flatten())
print(list.get(0)) // 0:index
print(list.remove(1))
print(list.removeAll([1,2]))

[1,1,2,3,“add”]
[1,1,“insert”,2,3]
[[1,4],[1,5],[2,6],[3,7]]
[3,2,1,1]
[2,3,1,1]
[4,5,6,7]
[22,33,44,55]
1
[1,2,3]
[3]

var List_1 = ee.List(['a','b','c'])
var List_2 = ee.List(['c','b', 'a'])
var List_3 = ee.List(['a','b'])

print(List_1.equals(List_2))  //false
print(List_1.contains('a'))   //true
print(List_1.containsAll(List_3))  //true

var List_number = ee.List([1,2,3,4,5,6,4,5,6,5,5,5])
print(List_number.indexOf(5)) //5 第一次 出现的 index      4
print(List_number.indexOfSublist([4,5,6]))  //[4,5,6] 第一次 出现的 index   3
print(List_number.lastIndexOfSubList([4,5,6]))    // 6
print(List_number.frequency(5)) // 5

var list = ee.List(['a','b'])
function Do(Name){
    
    
  return ee.List.repeat(Name, 3)
}
print(list.map(Do)) // [["a","a","a"],["b","b","b"]]

// 循环函数是 GEE非常不推荐一函数 
var list = ee.List.sequence(1,100,1)
function Do(number1, number2){
    
    
  return ee.Number(number1).add(number2)
}

print(list.iterate(Do, 0)) // 5050
print(list.size()) // 100

5.Array

var array1 = ee.Array([[1],[2],[3]])
var array2 = ee.Array([[1,2,3]])
print(ee.Array.identity(5))

List (5 elements)
0: [1,0,0,0,0]
1: [0,1,0,0,0]
2: [0,0,1,0,0]
3: [0,0,0,1,0]
4: [0,0,0,0,1]

ar array1 = ee.Array([[1,1],[2,2],[3,3],[4,4]])
var array2 = ee.Array([[0],[0],[1],[0]])
print(array1.mask(array2))   // [[3,3]]
// 转置    array1.transpose()