=COUNTIFS(A1:A9,"1",(A1:A9[-1],"0")) ???

Question

I'm in search of a formula for Numbers/Excel that will count the number of cells in a column containing the number 1 only if the previous cell in the column has a 0 in it. I originally thought that =COUNTIFS(A1:A9,"1",(A1:A9[-1],"0")) would work, however it returns with the error "A1:A9 isn't a valid reference." In the example below, the desired answer would be 2, as I only want the count the number of times that a "group" of 1's appears. I'm not sure whether this is even possible, if I have an error in the formula, or even if I have the wrong formula all together.
Any help would be greatly appreciated!
Thanks in advance,
Mikayla
0
0
1
1
1
0
1
1
0
0

Answer 1

Barry:
I appreciate your lengthy answer, but the text string "June 1st" is indeed meant to be text, not in date format, so I was only using "June 1st" as an example. The actual string that is in my data is "italy_final", which only appears once in column D on every sheet, but the row that it appears in varies.
Wayne:
I didn't mean to state how I would like the problem solved. I just thought that there would be some way to expand on the formula that Jeff suggested. Unfortunately, I cannot post the real data, as it is experimental data and its contents are sensitive. In addition, the spreadsheet is very large, 3572 rows and 17 columns to be exact.
Hiroto:
Your suggestion appears to be working well so far, however, I seem to have run into a roadblock. The words MarketW appears as groups in column J five times, but with a similar formula to the one you suggested, I can only seem to get it to return a count of 4 groups.
I have re-created a table with the ACTUAL data (while excluding some data that is not important):
A
B
C
D
E
F
G
H
I
J
K...
1
Practice
Market West Entrance
Market North Entrance
2
1.10
X
Y
Z
0
0
0
357
italy_final
358
15.6
X
Y
Z
0
0
0
MarketN
359
15.7
X
Y
Z
0
0
0
MarketN
360
15.8
X
Y
Z
0
0
0
MarketN
361
15.9
X
Y
Z
0
0
0
MarketW
362
16.0
X
Y
Z
0
0
0
MarketW
363
16.1
X
Y
Z
0
0
0
MarketW
364
16.2
X
Y
Z
0
0
0
MarketW
3571
419.2
X
Y
Z
0
0
0
3572
419.3
X
Y
Z
0
0
0
3573
# of (groups) of visits -->
=COUNTIFS(J$359:J$3572,"MarketW",J$358:J$3571,"-")
=COUNTIFS(OFFSET(J$1,D3573+1,0,3215-D3573),"MarketW",OFFSET(J$1,D3573,0,3215-D35 73),"-")
Please note the jump in rows (2-357), as I have skipped quite a few rows to shorten the data. Column A is time in milliseconds, and X,Y,Z are coordinates. "italy_final" appears only once in column D but varies in row location on each sheet. "MarketW" in column J appears in groups, sometimes filling more than 30 rows at a time, hence the reason I only wanted to count each group once and not each time "MarketW" appears. To count this, I used the formula that Jeff suggested, =COUNTIFS(J$359:J$3572,"MarketW",J$358:J$3571,"-"), and it worked great. Now, I need to keep the practice data up until "italy_final" on the sheet, but ignore this data in columns J and K before italy_final appears.
In short, I need a formula that will count the number of times "MarketW" and "MarketN" appears as a group in columns J and K beginning at the row that italy_final is located in. This is tough though, as I would like to be able to copy and paste the formula to my other sheets, but italy_final appears in a different row on each sheet.
Likely too complicated, but I would ultimately also like to add up the duration of time in column A that MarketW appears. In the example above, I would need to add the difference in time between row 364 and row 361, along with the other occurences of MarketW in column J.
I hope that makes sense and I appologize for (likely) making it more confusing than it needs to be.