Python dataframe get borders of zeros segments throught the column

Question

I have a pandas series:

s = [3,7,8,0,0,0,6,12,0,0,0,0,0,8,5,0,2]

I want to find all the indices in which there is a start or an end of a zeros segment, where the number of zeros is more than 3 so here I want to get:

[8,12]

What is the best way to do so?

Thanks

anky · Accepted Answer · 2019-02-15T11:37:42.483

1

I found this way using more_itertools considering s is the series (not list as you have provided):

First group the list in consecutive elements for the index that meets the condition:

import more_itertools as mit
a = [list(group) for group in mit.consecutive_groups(s.loc[s.eq(0)].index.tolist())]

Second , select the first and last entries form the list

list(set([i[0] for i in a]+[x[-1] for x in a]))
#[3, 5, 8, 12, 15]

EDIT for getting first and last index where 0 is more than 3 use:

list(set([i[0] for i in a if len(i)>3]+[x[-1] for x in a if len(x)>3]))
#[8, 12]

edited Feb 15 '19 at 11:37

answered Feb 15 '19 at 10:39

anky

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thank you , and if I want the segment of zeros will be with more than 3 zeros? – Cranjis Feb 15 '19 at 11:29
@okuoub didnt get that. you wanted the first and last index of consecutive zeroes right? the code does the same? – anky Feb 15 '19 at 11:31
yes but I want to filter out segments with less than 3 zeros (please see the edit) – Cranjis Feb 15 '19 at 11:35
@okuoub check EDIT acc to the new question use same solution with `list(set([i[0] for i in a if len(i)>3]+[x[-1] for x in a if len(x)>3]))` – anky Feb 15 '19 at 11:37

score 1 · Answer 2 · answered Feb 15 '19 at 10:41

1

s = [3,7,8,0,0,0,6,12,0,0,0,0,0,8,5,0,2]
idx = []
for i in range(len(s)):
    if s[i] == 0 and (s[i+1] != 0 or s[i-1] != 0):
        idx.append(i)
print (idx)
# result :[3, 5, 8, 12, 15]

answered Feb 15 '19 at 10:41

ncica

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and if I want the segment of zeros will be with more than 3 zeros? – Cranjis Feb 15 '19 at 11:27
the code is customized for any length of the list and the number of segments of zeros – ncica Feb 15 '19 at 12:57

score 0 · Answer 3 · answered Feb 15 '19 at 10:38

Define a flag that tells the loop whether to check the existence or absence of 0. entryFlag tells whether to check the entry of 0s or the exit.

s = [3,7,8,0,0,0,6,12,0,0,0,0,0,8,5,0,2]
entryFlag=True
i=0
s2=[]
for x in s:

    if entryFlag:
        if x==0:
            s2.append(i)
            entryFlag=False
    else:
        if x!=0:
            s2.append(i-1)
            entryFlag=True
    i+=1
print(s2)

Python dataframe get borders of zeros segments throught the column

3 Answers3