我有一个函数,可以查找数组中相邻值的百分比差异。
var values = [1.623,1.614,1.591,1.577,1.600,1.579,1.622]
values.reverse()
let percentages = [0] + zip(values, values.dropFirst()).map { (old, new) in
return (100.0 * (new - old) / old)
}
print(percentages)
[0.0, -2.651048088779294, 1.3299556681444034, -1.4375000000000082,0.8877615726062151, 1.445631678189826, 0.5576208178438598]
有没有办法将我的值格式化为如下所示
["+0.006%","+0.014%","+0.009%","-0.014%",">+0.013%","-0.027%"]
您可以从NumberFormatter
开始,例如...
let formatter = NumberFormatter()
formatter.numberStyle = .percent
formatter.minimumIntegerDigits = 1
formatter.maximumIntegerDigits = 1
formatter.maximumFractionDigits = 3
var values = [1.623,1.614,1.591,1.577,1.600,1.579,1.622]
values.reverse()
let percentages = [0] + zip(values, values.dropFirst()).map {
(old, new) in
return (100.0 * (new - old) / old)
}
print(percentages.compactMap { formatter.string(from: NSNumber(value: $0 / 100.0)) })
这将打印类似的东西....
["0%", "-2.651%", "1.33%", "-1.438%", "0.888%", "1.446%", "0.558%"]
您的字符串仅显示负数的信号。这不是OP要求的。
🙄 上帝禁止OP实际上必须做"一些"工作 🤣😉
print(percentages.map { ($0 >= 0 ? "+" : "") + formatter.string(for: $0 / 100.0)! })
或者,最好是...
formatter.positivePrefix = "+"
//....
print(percentages.compactMap { formatter.string(for: $0 / 100.0) })
哪些打印...
["+0%", "-2.651%", "+1.33%", "-1.438%", "+0.888%", "+1.446%", "+0.558%"]
如果可能的话,你能用例子来进一步解释一下如何捏造这些数字吗?
值的格式似乎与您正在生成的值不匹配,例如,0.8877615726062151
0.8%
,而不是0.009%
,因此您有一个轻微的自定义,最好通过稍微"捏造"值来实现。
所以,再一次,从...
let formatter = NumberFormatter()
formatter.numberStyle = .percent
formatter.minimumIntegerDigits = 1
formatter.maximumIntegerDigits = 1
formatter.maximumFractionDigits = 3
formatter.minimumFractionDigits = 3
formatter.positivePrefix = "+"
我修改了
print(percentages.compactMap { formatter.string(for: $0 / 100.0) })
自
print(percentages.compactMap { formatter.string(for: $0 / 10000.0) })
现在打印
["+0.000%", "-0.027%", "+0.013%", "-0.014%", "+0.009%", "+0.014%", "+0.006%"]
根据我的观察,这似乎是您的目标 - 您只需免费获得本地化
只需在映射闭包中返回字符串
let percentages = [0] + zip(values, values.dropFirst()).map { (old, new) in
let value = (100.0 * (new - old) / old)
return String(format: "%.3f%%", value)
}
[0.0, -2.651048088779294, 1.3299556681444034, -1.4375000000000082, 0.8877615726062151, 1.445631678189826, 0.5576208178438598]
.map{String(format:"%+6.3f%%",$0/100)}
这将提供 +/- 符号。