Pandas - Find first occurance of number closest to an input value-CodePudding

I have a dataframe like below.

   time  speed
0     1   0.20
1     2   0.40
2     3   2.00
3     4   3.00
4     5   0.40
5     6   0.43
6     7   6.00

I would like to find the first occurance of a number ( in 'Speed' Column) that is closest to an input value I enter.

For example :

input value = 0.43

Expected Output :

Speed : 0.40 & corresponding Time : 2

The speed column should not be sorted for this problem.

I tried the below,but not getting the expected output.

Any help on this would be appreciated.

CodePudding user response：

You can compute the absolute difference to your reference and get the idxmin:

speed_input = 0.43
df.loc[abs(df['speed']-speed_input).idxmin()]

output:

time     6.00
speed    0.43
Name: 5, dtype: float64

i = 0.43
thresh = 0.03
df.loc[abs(df['speed']-i).le(thresh).idxmax()]

output:

time     2.0
speed    0.4
Name: 1, dtype: float64

CodePudding user response：

One idea is round both values:

df[[(df['speed'].round(1)-round(speed_input, 1)).abs().idxmin()]]