ebashi wrote:
I'll appreciate if some one can help me with the
following loop. This is the logic of the loop,
if we have the following data;

x.df

x.dif
. .
. .
102 0.00
103 0.42
104 0.08
105 0.00
106 0.00
107 0.00
108 -0.16
109 -0.34
110 0.00
111 -0.17
112 -0.33
113 0.00
114 0.00
115 0.00
116 0.33
117 0.17
118 0.00 . .
. .
I'm trying to find i's where for (i in 2:length(x.dif))
if (x.dif[i-1]<=0 and x.dif[i]>0 and x.dif[i+2]>0)

Solution to the question:

a) you cannot loop to length(x.dif), x.dif[i+2] does not exist for i==length(x.dif).
b) Use && instead of "and" in this case
c) vector operations are much mor


Hint: If you lengthen the vectors appropriately, you can apply the comparisons vectorized rather than in a loop...

Uwe Ligges

  it would return i+2 to me,
How can I turn this to a right format as a loop.(I
can't figure out the syntax)

Cheers,

Sean

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