How to Check Value of Cells in Range VBA

Question

I am trying to take a range of cells (column B to be specific) and find the cells in that range that have a value less than zero and clear the contents of those cells. Is there a way to do this without looping through every single cell? The column is a very large data set that gets longer each week so looping takes a significant amount of time.

Below is the current loop I am using

Dim sht As Worksheet
Dim LastColumn As Long
Set sht = ThisWorkbook.Worksheets("Sheet1")
lastrow = sht.Cells.Find("*", SearchOrder:=xlByRows, 
searchdirection:=xlPrevious).Row
for i=1 to lastrow
if sheets("time").cells(i, "B") then
sheets("time").cells(i, "B").clear
end if
next i

The cells I am trying to examine and then potentially delete contain formulas

edit: The answer marked as accepted sped up the process but still requires a loop. If anyone has anything that would be faster than what is posted feel free to add it.

Answer 1

As per my comment. I run this on 50k rows, took minor amounts of time.

Option Explicit

Sub update_column()
Dim Column_to_run_on As String
Dim LR As Long, i As Long
Dim arr As Variant

'change as needed
Column_to_run_on = "D"

'change sheet as needed
With Sheets("Sheet1")
    LR = .Range(Column_to_run_on & "1048575").End(xlUp).Row

    '"2:" here as I assume you have a header row so need to start from row 2
    arr = .Range(Column_to_run_on & "2:" & Column_to_run_on & LR)

    For i = 1 To UBound(arr, 1)
        If arr(i, 1) < 0 Then
            arr(i, 1) = 0
        End If
    Next

    .Range(Column_to_run_on & "2:" & Column_to_run_on & LR).Value = arr
End With
End Sub

Answer 2

No loop is needed. Say we have data in B1 through B21 like:

This tiny macro:

Sub RemoveNegs()

    With Range("B1:B21")
        .Value = Evaluate("IF(" & .Address & " < 0,""""," & .Address & ")")
    End With


End Sub

will produce:

Not appropriate if the cells contain formulas.

Answer 3

i tested lopps with vba array against both solutions, loops is at least 2 to 5 times faster in each case:

Option Explicit

Sub fill()
Dim t As Double
t = Timer
Dim x&
Dim y&
Dim arr()
With Application
    .ScreenUpdating = False
    .EnableEvents = False
    .Calculation = xlCalculationManual

    ReDim arr(1 To 2000, 1 To 1000)

    For x = 1 To 1000
        For y = 1 To 2000
            arr(y, x) = Rnd() * 1111 - 555
        Next y
    Next x

    Range(Cells(1, 1), Cells(2000, 1000)).Value2 = arr

    .ScreenUpdating = True
    .Calculation = xlCalculationAutomatic
    .EnableEvents = True
    Debug.Print Timer - t
End With
Erase arr

End Sub


Sub nega()
Dim t As Double
t = Timer
Dim x&
Dim y&
Dim arr()
With Application
    .ScreenUpdating = False
    .EnableEvents = False
    .Calculation = xlCalculationManual

    'With Range("A1", Cells(2000, 1000))
    '    .Value2 = Evaluate("if(" & .Address & " <0,""""," & .Address & ")")
    'End With


    'Range(Cells(1, 1), Cells(2000, 1000)).Replace "-*", ""

    arr = Range(Cells(1, 1), Cells(2000, 1000)).Value2

    For x = 1 To 1000
        For y = 1 To 2000
            If arr(y, x) < 0 Then arr(y, x) = vbNullString
        Next y
    Next x

    Range(Cells(1, 1), Cells(2000, 1000)).Value2 = arr

    .ScreenUpdating = True
    .Calculation = xlCalculationAutomatic
    .EnableEvents = True

End With
Erase arr
Debug.Print Timer - t 
End Sub