filter

filter(gpt, cond)

Returns a subset of gpt according to the filter conditions defined in cond.

Parameters

  • gpt (Geopoints) – input geopoints

  • cond (number or datetime.datetime or list or ndarray or Geopoints) – filter conditions

Return type

Geopoints

The actual filtering is based on the type of cond:

  • if cond is a Geopoints it must have the same number of values as gpt. The result will contain the values of gpt where the value of cond is non-zero. It is usually combined with the comparison operators.

    Example

    This code shows how to filter the negative values in a Geopoints containing temperature in K.

    import metview as mv

t = mv.read("temp.gpt")
freeze = mv.filter(t,t < 273.16)

  • if cond is an ndarray it must have the same number of values as gpt. The result will contain the values of gpt where the value of cond is non-zero. It is usually combined with the comparison operators.

    Example
    import metview as mv

gpt = mv.read("my_date.gpt")

# "gpt["precip"] > 5" returns a vector of 1s and 0s
new_gpt = mv.filter(gpt, gpt["precip"] > 5)

  • if cond is number or list of numbers in the format of [min_level, max_level] it defines a filter on the level column of gpt. The result will contain the values of gpt where the level equals to cond (if it is a number) or in the interval specified by cond (if it is a list).

  • if cond is datetime.datetime or list of it in the format of [min_date, max_date] it defines a filter on the date column of gpt. The result will contain the values of gpt where the date equals to cond (if it is a datetime.datetime) or in the interval specified by cond (if it is a list).

  • if cond is a list in the format of [North, West, South, East] format it defines a filter with a geographical area. The result will contain the values of gpt where the locations are within cond.