Finding cell location in python

Question

I am relatively new to python and trying to locate the cell that contains the value "3275" which is here, the "newELA". This value is in the top row of the spreadsheet and is a header. This is what I have been trying:

loc=("/Volumes/Project/Andes_Glacier_Inventory.xlsx")
wb = xlrd.open_workbook(loc)
sheet = wb.sheet_by_index(1)
headers = sheet.row(0)[3:]

a = np.array(sheet.row_values(1,3))

value = 501
ELA = headers[np.argmax(a * (a < value))]
print ("The ELA is", ELA.value)

changeinELA = 100
value1 = changeinELA
value2 = ELA.value
newELA = float(value1) + float(value2)
print ("The new ELA is", newELA)

b = np.where (np.array(headers) == newELA)
print (b)

The results I am getting are, which I don't even understand

(array([], dtype=int64),)

Could you please provide the entire code, such as how the `sheet` is obtained? — Pierre, Jan 06 '19 at 11:11
Your result seem to be an empy numpy array. Yep, as @Pierre suggested, could you provide more code? — zabop, Jan 06 '19 at 11:28
`b` is the indices where the `==` is true - in this case there aren't any. If you showed us `headers` and `newELA` it might help. — hpaulj, Jan 06 '19 at 18:07

score 1 · Accepted Answer · answered Jan 06 '19 at 11:35

You can see How does python numpy where work?. The value "3275" is a string. On the other hand, you have an array of integers and the newELA is float. You have to decide in which dtype the headers array is and it should be the same with the newELA variable. For example,

import numpy as np
headers = [200, 100, 300]
a = np.array(headers)
b = np.where (a == 300)
print(b)

output

(array([2], dtype=int64),)

score 0 · Answer 2 · answered Jan 07 '19 at 13:09

You are getting an empty array because there is nothing in your headers which is equal to your newELA value.

Check your data. Just a thought of what could be your problem: If there is a floating point error, you can do the following:

tol = 1e-10   #change accordingly
b = np.where (np.abs(np.array(headers, dtype=np.float) - newELA) < tol) #passing dtype=np.float will convert your strings, if you need to
print (b)

Finding cell location in python

2 Answers2