require explicit predicates in find functions

fix #23120, fix #19186

Author: JeffBezanson

NEWS.md

@@ -468,6 +468,12 @@ Deprecated or removed
   * The timing functions `tic`, `toc`, and `toq` are deprecated in favor of `@time` and `@elapsed`
     ([#17046]).
 
+  * Methods of `findfirst`, `findnext`, `findlast`, and `findprev` that accept a value to
+    search for are deprecated in favor of passing a predicate ([#19186], [#10593]).
+
+  * `find` functions now operate only on booleans by default. To look for non-zeros, use
+    `x->x!=0` or `!iszero` ([#23120]).
+
 Command-line option changes
 ---------------------------
 

base/array.jl

@@ -1596,14 +1596,14 @@ cat(n::Integer, x::Integer...) = reshape([x...], (ntuple(x->1, n-1)..., length(x
 """
     findnext(A, i::Integer)
 
-Find the next linear index >= `i` of a non-zero element of `A`, or `0` if not found.
+Find the next linear index >= `i` of a true element of `A`, or `0` if not found.
 
 # Examples
 ```jldoctest
-julia> A = [0 0; 1 0]
-2×2 Array{Int64,2}:
- 0  0
- 1  0
+julia> A = [false false; true false]
+2×2 Array{Bool,2}:
+ false  false
+  true  false
 
 julia> findnext(A,1)
 2
@@ -1615,8 +1615,14 @@ julia> findnext(A,3)
 function findnext(A, start::Integer)
     l = endof(A)
     i = start
+    warned = false
     while i <= l
-        if A[i] != 0
+        a = A[i]
+        if !warned && !(a isa Bool)
+            depwarn("In the future `findnext` will only work on boolean collections. Use `findnext(x->x!=0, A)` instead.", :findnext)
+            warned = true
+        end
+        if a != 0
             return i
         end
         i = nextind(A, i)
@@ -1646,58 +1652,6 @@ julia> findfirst(zeros(3))
 """
 findfirst(A) = findnext(A, 1)
 
-"""
-    findnext(A, v, i::Integer)
-
-Find the next linear index >= `i` of an element of `A` equal to `v` (using `==`), or `0` if not found.
-
-# Examples
-```jldoctest
-julia> A = [1 4; 2 2]
-2×2 Array{Int64,2}:
- 1  4
- 2  2
-
-julia> findnext(A,4,4)
-0
-
-julia> findnext(A,4,3)
-3
-```
-"""
-function findnext(A, v, start::Integer)
-    l = endof(A)
-    i = start
-    while i <= l
-        if A[i] == v
-            return i
-        end
-        i = nextind(A, i)
-    end
-    return 0
-end
-"""
-    findfirst(A, v)
-
-Return the linear index of the first element equal to `v` in `A`.
-Returns `0` if `v` is not found.
-
-# Examples
-```jldoctest
-julia> A = [4 6; 2 2]
-2×2 Array{Int64,2}:
- 4  6
- 2  2
-
-julia> findfirst(A,2)
-2
-
-julia> findfirst(A,3)
-0
-```
-"""
-findfirst(A, v) = findnext(A, v, 1)
-
 """
     findnext(predicate::Function, A, i::Integer)
 
@@ -1754,14 +1708,14 @@ findfirst(testf::Function, A) = findnext(testf, A, 1)
 """
     findprev(A, i::Integer)
 
-Find the previous linear index <= `i` of a non-zero element of `A`, or `0` if not found.
+Find the previous linear index <= `i` of a true element of `A`, or `0` if not found.
 
 # Examples
 ```jldoctest
-julia> A = [0 0; 1 2]
-2×2 Array{Int64,2}:
- 0  0
- 1  2
+julia> A = [false false; true true]
+2×2 Array{Bool,2}:
+ false  false
+  true  true
 
 julia> findprev(A,2)
 2
@@ -1772,8 +1726,14 @@ julia> findprev(A,1)
 """
 function findprev(A, start::Integer)
     i = start
+    warned = false
     while i >= 1
-        A[i] != 0 && return i
+        a = A[i]
+        if !warned && !(a isa Bool)
+            depwarn("In the future `findprev` will only work on boolean collections. Use `findprev(x->x!=0, A)` instead.", :findprev)
+            warned = true
+        end
+        a != 0 && return i
         i = prevind(A, i)
     end
     return 0
@@ -1806,59 +1766,6 @@ julia> findlast(A)
 """
 findlast(A) = findprev(A, endof(A))
 
-"""
-    findprev(A, v, i::Integer)
-
-Find the previous linear index <= `i` of an element of `A` equal to `v` (using `==`), or `0` if not found.
-
-# Examples
-```jldoctest
-julia> A = [0 0; 1 2]
-2×2 Array{Int64,2}:
- 0  0
- 1  2
-
-julia> findprev(A, 1, 4)
-2
-
-julia> findprev(A, 1, 1)
-0
-```
-"""
-function findprev(A, v, start::Integer)
-    i = start
-    while i >= 1
-        A[i] == v && return i
-        i = prevind(A, i)
-    end
-    return 0
-end
-
-"""
-    findlast(A, v)
-
-Return the linear index of the last element equal to `v` in `A`.
-Returns `0` if there is no element of `A` equal to `v`.
-
-# Examples
-```jldoctest
-julia> A = [1 2; 2 1]
-2×2 Array{Int64,2}:
- 1  2
- 2  1
-
-julia> findlast(A,1)
-4
-
-julia> findlast(A,2)
-3
-
-julia> findlast(A,3)
-0
-```
-"""
-findlast(A, v) = findprev(A, v, endof(A))
-
 """
     findprev(predicate::Function, A, i::Integer)
 
@@ -1952,9 +1859,7 @@ _index_remapper(iter) = OneTo(typemax(Int))  # safe for objects that don't imple
 """
     find(A)
 
-Return a vector of the linear indexes of the non-zeros in `A` (determined by `A[i]!=0`). A
-common use of this is to convert a boolean array to an array of indexes of the `true`
-elements. If there are no non-zero elements of `A`, `find` returns an empty array.
+Return a vector of the linear indices of the true values in `A`.
 
 # Examples
 ```jldoctest
@@ -1968,7 +1873,7 @@ julia> find(A)
  1
  4
 
-julia> find(zeros(3))
+julia> find(falses(3))
 0-element Array{Int64,1}
 ```
 """
@@ -1977,7 +1882,12 @@ function find(A)
     I = Vector{Int}(nnzA)
     cnt = 1
     inds = _index_remapper(A)
+    warned = false
     for (i,a) in enumerate(A)
+        if !warned && !(a isa Bool)
+            depwarn("In the future `find(A)` will only work on boolean collections. Use `find(x->x!=0, A)` instead.", :find)
+            warned = true
+        end
         if a != 0
             I[cnt] = inds[i]
             cnt += 1
@@ -1986,7 +1896,7 @@ function find(A)
     return I
 end
 
-find(x::Number) = x == 0 ? Array{Int,1}(0) : [1]
+find(x::Bool) = x ? [1] : Array{Int,1}(0)
 find(testf::Function, x::Number) = !testf(x) ? Array{Int,1}(0) : [1]
 
 findn(A::AbstractVector) = find(A)

base/combinatorics.jl

@@ -75,7 +75,7 @@ function permute!!(a, p::AbstractVector{<:Integer})
     count = 0
     start = 0
     while count < length(a)
-        ptr = start = findnext(p, start+1)
+        ptr = start = findnext(!iszero, p, start+1)
         temp = a[start]
         next = p[start]
         count += 1
@@ -125,7 +125,7 @@ function ipermute!!(a, p::AbstractVector{<:Integer})
     count = 0
     start = 0
     while count < length(a)
-        start = findnext(p, start+1)
+        start = findnext(!iszero, p, start+1)
         temp = a[start]
         next = p[start]
         count += 1

base/datafmt.jl

@@ -370,7 +370,7 @@ function val_opts(opts)
     for (opt_name, opt_val) in opts
         in(opt_name, valid_opts) ||
             throw(ArgumentError("unknown option $opt_name"))
-        opt_typ = valid_opt_types[findfirst(valid_opts, opt_name)]
+        opt_typ = valid_opt_types[findfirst(Base.equalto(opt_name), valid_opts)]
         isa(opt_val, opt_typ) ||
             throw(ArgumentError("$opt_name should be of type $opt_typ, got $(typeof(opt_val))"))
         d[opt_name] = opt_val

base/deprecated.jl

@@ -1855,6 +1855,12 @@ end
     nothing
 end
 
+@deprecate find(x::Number)            find(!iszero, x)
+@deprecate findnext(A, v, i::Integer) findnext(x->x==v, A, i)
+@deprecate findfirst(A, v)            findfirst(x->x==v, A)
+@deprecate findprev(A, v, i::Integer) findprev(x->x==v, A, i)
+@deprecate findlast(A, v)             findlast(x->x==v, A)
+
 # END 0.7 deprecations
 
 # BEGIN 1.0 deprecations

base/event.jl

@@ -234,7 +234,7 @@ function ensure_rescheduled(othertask::Task)
         # if the current task was queued,
         # also need to return it to the runnable state
         # before throwing an error
-        i = findfirst(Workqueue, ct)
+        i = findfirst(t->t===ct, Workqueue)
         i == 0 || deleteat!(Workqueue, i)
         ct.state = :runnable
     end

base/file.jl

@@ -271,7 +271,7 @@ function tempname(temppath::AbstractString,uunique::UInt32)
     tempp = cwstring(temppath)
     tname = Vector{UInt16}(32767)
     uunique = ccall(:GetTempFileNameW,stdcall,UInt32,(Ptr{UInt16},Ptr{UInt16},UInt32,Ptr{UInt16}), tempp,temp_prefix,uunique,tname)
-    lentname = findfirst(tname,0)-1
+    lentname = findfirst(Base.equalto(0),tname)-1
     if uunique == 0 || lentname <= 0
         error("GetTempFileName failed: $(Libc.FormatMessage())")
     end

base/inference.jl

@@ -1583,7 +1583,7 @@ function builtin_tfunction(@nospecialize(f), argtypes::Array{Any,1},
         end
         tf = t_ifunc[iidx]
     else
-        fidx = findfirst(t_ffunc_key, f)
+        fidx = findfirst(x->x===f, t_ffunc_key)
         if fidx == 0
             # unknown/unhandled builtin function
             return Any
@@ -4757,7 +4757,7 @@ function statement_cost(ex::Expr, line::Int, src::CodeInfo, mod::Module, params:
                 elseif f == Main.Core.arrayref
                     return plus_saturate(argcost, isknowntype(ex.typ) ? 4 : params.inline_nonleaf_penalty)
                 end
-                fidx = findfirst(t_ffunc_key, f)
+                fidx = findfirst(x->x===f, t_ffunc_key)
                 if fidx == 0
                     # unknown/unhandled builtin or anonymous function
                     # Use the generic cost of a direct function call
@@ -5604,7 +5604,7 @@ function _getfield_elim_pass!(e::Expr, sv::InferenceState)
             if alloc !== false
                 flen, fnames = alloc
                 if isa(j, QuoteNode)
-                    j = findfirst(fnames, j.value)
+                    j = findfirst(x->x == j.value, fnames)
                 end
                 if 1 <= j <= flen
                     ok = true
@@ -5899,7 +5899,7 @@ function replace_getfield!(e::Expr, tupname, vals, field_names, sv::InferenceSta
                 a.args[3]
             else
                 @assert isa(a.args[3], QuoteNode)
-                findfirst(field_names, a.args[3].value)
+                findfirst(x->x == a.args[3].value, field_names)
             end
             @assert(idx > 0) # clients should check that all getfields are valid
             val = vals[idx]

base/operators.jl

@@ -972,3 +972,5 @@ julia> filter(!isalpha, str)
 ```
 """
 !(f::Function) = (x...)->!f(x...)
+
+equalto(y) = x->isequal(x,y)

base/permuteddimsarray.jl

@@ -148,7 +148,7 @@ function _copy!(P::PermutedDimsArray{T,N,perm}, src) where {T,N,perm}
         copy!(parent(P), src) # it's not permuted
     else
         R1 = CartesianRange(indices(src)[1:d])
-        d1 = findfirst(perm, d+1)  # first permuted dim of dest
+        d1 = findfirst(Base.equalto(d+1), perm)  # first permuted dim of dest
         R2 = CartesianRange(indices(src)[d+2:d1-1])
         R3 = CartesianRange(indices(src)[d1+1:end])
         _permutedims!(P, src, R1, R2, R3, d+1, d1)